HK40000080A - Methods and devices for soft tissue dissection - Google Patents

Description

Method and apparatus for soft tissue dissection

The invention is a divisional application with the application number of 201380034142.3 as the parent, the application date of 2013, 4 and 29 as the name of 'method and device for soft tissue dissection'.

Priority application

Priority of U.S. provisional patent application No. 61/687,587, entitled "instrument for Soft Tissue Dissection" filed on 28/4/2012, the entire contents of which are incorporated herein by reference.

This application also claims priority from U.S. provisional patent application No. 61/744,936 entitled "Instrument for Soft Tissue Dissection" filed on 6/10/2012, the entire contents of which are incorporated herein by reference.

This application also claims priority from U.S. provisional patent application No. 61/783,834, entitled "Instruments and Devices for Soft tissue dissection and Related Methods" (Instruments, Devices and Related Methods) filed on 2013, month 14, the entire contents of which are incorporated herein by reference.

RELATED APPLICATIONS

This application relates To U.S. provisional patent application No. 61/631,432, entitled "method and Devices To Reduce Tissue damage During Surgery" (method and Devices To Reduce Tissue train dual surface), filed on 4/1/2012, the entire contents of which are incorporated herein by reference.

This application relates To U.S. provisional patent application No. 61/632,048, entitled "method and Devices To Reduce Tissue damage During Surgery" (filed on day 1, month 17 of 2012), the entire contents of which is incorporated herein by reference.

Technical Field

The field of the present disclosure relates to methods or devices for dissecting tissue during surgery or other medical procedures.

Background

Surgeons often need to cut through tissue during surgical procedures. Two techniques are commonly used: (1) "sharp dissection": the surgeon slices the tissue using a cutting instrument, cutting using a surgical scissors, scalpel, electrotome, or other slicing instrument; and, (2) blunt dissection.

Surgeons often need to cut through tissue during surgical procedures. Two techniques are commonly used: (1) "sharp dissection": the surgeon slices the tissue using a cutting instrument, cutting using a surgical scissors, scalpel, electrotome, or other slicing instrument; and, (2) blunt dissection.

An advantage of sharp dissection is that the cutting instrument easily severs any tissue. The cutting itself is indistinguishable and the instrument is applied to cut through any and all tissue. This is also a disadvantage of sharp dissection when the first tissue is embedded in and obscured by the second tissue (or more commonly in many tissues), especially when trying to isolate the first tissue without damaging it. For example, accidental cutting of blood vessels, nerves or intestines is not uncommon, even for most experienced surgeons, and can lead to serious and even life-threatening intraoperative complications and can have a lasting impact on the patient.

Thus, isolating a first tissue embedded in other tissue is typically performed using blunt dissection. In blunt dissection, a blunt instrument is used to push through the tissue, force the two tissues apart, or otherwise separate the tissues by tearing rather than cutting. Almost all procedures require blunt dissection of tissue to expose target structures, such as blood vessels to be ligated or nerve bundles to be avoided. Examples of thoracic surgery include: blood vessels were isolated during pulmonic dissection to allow for lobe excision and lymph node exposure.

Blunt dissection includes numerous manipulations, including various ways of tearing soft tissue, such as: the insertion of a blunt probe or instrument, the reverse manipulation (i.e., deployment) of the forceps, and the pulling of tissue with the forceps or the rubbing with a "swab dissector" (e.g., surgical gauze clamped in the forceps). When needed, sharp dissection is used cautiously to cut tissue that resists tearing in blunt dissection.

The general objective is to tear or otherwise damage tissue (such as membranes and mesenteries) away from a target structure without tearing or damaging the target structure or critical structures (such as nearby blood vessels or nerves). Surgeons take advantage of different mechanical behavior of tissues, such as different stiffness of adjacent tissues or the presence of softer tissue planes between harder tissues. Generally, the aim is to isolate mechanically stiff target tissue consisting of more tightly packed (packed) fibrous components, and the target tissue is embedded in mechanically soft tissue consisting of more loosely packed fibrous components. More tightly packed fibrous tissue, including tissue composed of tightly packed collagen and other fibrous connective tissue, generally has an anisotropic distribution of fibrous components of high tissue, generally with a layered composite. Examples include blood vessels, nerve sheaths, muscles, fascia, bladder, and tendons. Loosely aggregated fibrous tissue has a lower number of fibers per unit volume or is composed of materials with less optimal tissue such as fat and mesentery. Fibrous components include fibers, fibrils, filaments, and other filamentous components. When a tissue is referred to as "fibrous," it generally refers to extracellular filamentous components, such as collagen and elastin, that polymerize into linear structures of varying complexity to form the extracellular matrix. As mentioned in the preceding paragraph, the density, orientation and organization of the fibrous components largely determine the mechanical behavior of the tissue. Sometimes, the tissue is referred to as "tough fibrous tissue," indicating that the fibrous or filamentous components are densely packed and comprise a large portion of the tissue mass. However, all tissues are fibrous to some extent, and in fact, there are fibers and other filamentous extracellular components present in the tissues.

For the present discussion, it is important that softer tissue tears more easily than harder tissue (firm tissue), and therefore blunt dissection is attempted by applying sufficient force to tear softer tissue rather than harder tissue.

Blunt dissection can be difficult and often time consuming. It is not easy to judge if the force is tearing soft tissue rather than hard tissue in close proximity. Thus, the blood vessel may be torn. The nerve may be stretched or torn. In this regard, surgeons attempt to perform careful sharp dissection, but may cut blood vessels and nerves, particularly small side branches. All of this results in a long, tedious anatomy and increases the risk of complications such as bleeding, lung leaks, and nerve damage.

Surgeons typically use forceps for blunt dissection. Figures 1A and 1B illustrate a typical forceps 10 of the prior art. FIG. 1A shows forceps 10 in a closed position for clamping tissue 34 between opposing first and second clamping members 30, 31. Fig. 1B shows forceps 10 in an open position with tissue 34 separated. A first finger grip 20 and an opposite second finger grip 21 are used to actuate the mechanism. The first finger grip 20 actuates the first gripping element 30 and the second finger grip 21 actuates the second gripping element 31. The pivot 40 attaches the first and second clamping members 30 and 31, allowing a surgical scissor-like action to force the first and second clamping members 30 and 31 together or apart to clamp the tissue 34 between the two clamping surfaces 35 and 36 or to split the tissue 34 by spreading the first and second clamping members 30 and 31 apart. The first clamping member 30 and the second clamping member 31 are typically locked together using a ratchet clasp 50.

Laparoscopic and thoracoscopic (collectively "endoscopic") instruments use similar motions. Fig. 2 shows a prior art endoscopic forceps 110. A first finger grip 120 and an opposing second finger grip 121 are used to actuate the mechanism. The first finger tab 120 is rigidly mounted to the instrument body 150. Second finger grip 121 actuates opposing gripping elements 130 and 131. Pivot 140 attaches two clamping elements 130 and 131 such that actuation of second finger grip 121 forces clamping elements 130 and 131 together to clamp tissue between two clamping surfaces 135 and 136. As shown in fig. 1, endoscopic forceps 110 may be used to separate tissue. Clamping elements 130 and 131 are closed, inserted into tissue, and then reopened to tear the tissue.

For either of the surgical forceps 10 or the endoscopic forceps 110, the surgeon performs blunt dissection by: the forceps are closed, the closed forceps are advanced into the tissue, and the forceps are then optionally opened within the tissue and the tissue is torn using the force applied when opening the jaws of the forceps. Thus, the surgeon dissects tissue by combining pushing tissue in and opening the jaws of the forceps.

Blunt dissection is commonly used for moist and smooth tissue, and the smooth passive surface of most surgical instruments tends to slide along the tissue, thereby impairing the ability of the instrument to gain grip and separate tissue. Furthermore, the surgeon has only limited control and can only make pokes, side dials, or parts. An improved blunt dissection instrument that differentially separates soft tissue without destroying hard tissue would greatly facilitate many surgical procedures.

Disclosure of Invention

Embodiments disclosed herein include methods and devices for blunt dissection that differentially disrupt soft tissue but not hard tissue. In particular, in one embodiment, a differential dissecting instrument for differentially dissecting complex tissue is disclosed. The differential dissecting instrument includes a handle and an elongated member having a first end and a second end, wherein the first end is connected to the handle. The differential dissecting instrument further comprises a differential dissecting member configured to be rotatably attached to the second end, the differential dissecting member comprising at least one tissue engaging surface. The differential dissecting instrument further comprises a mechanism configured to mechanically rotate the differential dissecting member about an axis of rotation to thereby move the at least one tissue-engaging surface in at least one direction against the composite tissue. The at least one tissue engaging surface is configured to selectively engage the composite tissue such that, upon pressing the differential dissecting member into the composite tissue, the at least one tissue engaging surface moves across the composite tissue and the at least one tissue engaging surface disrupts at least one soft tissue in the composite tissue, but does not disrupt hard tissue in the composite tissue.

In another embodiment, a differential dissecting member for dissecting complex tissue is disclosed. The differential dissecting member includes a body having a first end and a second end with a central axis from the first end to the second end. The first end is configured to be oriented away from the complex tissue and configured to engage a drive mechanism that moves the differential dissecting member, thereby sweeping the second end in a direction of motion. The second end includes a tissue-facing surface configured to be oriented toward the composite tissue. The tissue-facing surface includes at least one tissue-engaging surface comprised of a series of at least one valley and at least one protrusion staggered along the direction of motion on the tissue-facing surface such that an intersection of the at least one valley and at least one protrusion defines at least one valley edge having a directional component perpendicular to the direction of motion. In one embodiment, the at least one valley edge is not sharp.

Drawings

FIGS. 1A and 1B illustrate an example of the prior art; FIG. 1A shows a forceps for grasping tissue;

FIG. 1B illustrates an exemplary surgical clamp for segmenting tissue in blunt dissection;

figure 2 shows a prior art laparoscopic forceps;

fig. 3A-3F illustrate an exemplary differential dissecting instrument. Fig. 3A-3C illustrate a differential dissecting instrument having a rotatable differential dissecting member within a shield. FIG. 3D illustrates a front view and a side view of the differential dissecting member. FIG. 3E illustrates four different types of differential dissecting members. FIG. 3F illustrates the differential dissecting member, including the tissue to be dissected, in a front view and a side view;

fig. 4A-4F illustrate how an exemplary differential dissecting instrument disrupts soft tissue in composite tissue but does not disrupt hard tissue to expose hard tissue. 4D-4F illustrate how the differential dissecting instrument engages and disrupts tissue having a dispersed fibrous component but is unable to engage and thereby disrupt the fibrous component;

fig. 5A-5C illustrate tissue engaging ends of different exemplary differential dissecting instruments including a dissecting wheel mounted within a shroud. FIGS. 5A-5B illustrate an instrument having a dissection wheel of one configuration, while FIG. 5C illustrates another instrument having a dissection wheel of a different configuration;

6A-6D illustrate different configurations of exemplary differential dissecting members in differential dissecting instruments, including differential dissecting instruments having flexible or articulating elongated members, illustrating how the axes of rotation of the differential dissecting members can have many different orientations relative to the differential dissecting instrument;

FIGS. 7A and 7B illustrate an exemplary differential dissecting instrument using an dissection line in place of a dissector wheel or other differential dissecting member;

8A-8C illustrate an exemplary differential dissecting instrument that uses a flexible band as the differential dissecting member;

FIGS. 9A-9C illustrate how different exposures of the tissue engaging surfaces of the differential dissecting member change the behavior of the differential dissecting instrument, particularly the range of exposure angles of the tissue engaging surfaces;

10A-10C illustrate how different exposures of the tissue engaging surfaces of the differential dissecting member change the direction of frictional forces on tissue to change the strain angle on the tissue;

11A and 11B illustrate an exemplary differential dissecting instrument having a water outlet port that exits alongside the differential dissecting member;

FIG. 12 illustrates an exemplary differential dissecting instrument having two opposing flexible bands that generate opposing frictional forces thereby reducing torque on the differential dissecting instrument;

FIG. 13 illustrates an exemplary differential dissecting instrument that may have a plurality of components placed within the shroud, including an aspiration line, a water tube, and a light emitting diode;

FIG. 14 illustrates how the elongated members of an exemplary differential dissecting instrument may be articulated with bendable regions to facilitate placement of the differential dissecting members;

15A-15E illustrate different exemplary differential anatomical members illustrating several important dimensions and features of the differential anatomical members;

FIG. 16 illustrates an exemplary apparatus for changing an aggressiveness level of a differential anatomical member;

fig. 17A and 17B illustrate how features of the tissue engaging surface (such as scallops) cause the tissue engaging surface to have a varying angle of attack as it moves over tissue;

FIG. 18 illustrates how the relative arrangement of the center of rotation and center of gravity of the oscillating differential dissecting member may cause the differential dissecting instrument to vibrate;

fig. 19A-19D illustrate how an exemplary differential dissecting member or shield covering it may tension tissue in a direction perpendicular to the direction of motion of the tissue engaging surface. FIG. 19D illustrates how this tension may align the fibrous components within the tissue, thereby facilitating destruction of the fibrous components by the tissue engaging surface;

FIG. 20 further illustrates how the exemplary differential dissecting members disrupt tissue, including how the differential dissecting members strain tissue and disrupt fibrous components, such as interstitial fibers;

21A-21C illustrate how relative movement of the shroud and differential dissecting member of the differential dissecting instrument changes the wedging angle so that more or less strain may be created in the tissue;

FIG. 22 illustrates one example of an exemplary reciprocating mechanism for a differential dissecting member that converts rotation of a shaft into reciprocating oscillation of the differential dissecting member using a scotch yoke mechanism;

fig. 23A to 23C further illustrate the scotch yoke mechanism shown in fig. 22;

FIGS. 24A and 24B further illustrate the scotch yoke mechanism shown in FIG. 22;

25A-25D further illustrate the scotch yoke mechanism shown in FIG. 22, including how more differential anatomical members may be housed in the shield to reduce trauma to patient tissue;

FIGS. 26A and 26B illustrate how exemplary differential dissecting members may be adapted with retractable blades such that the differential dissecting instrument may also dissect tissue sharply;

FIG. 27 shows how an exemplary differential dissecting member may be adapted with a fastening member to allow the differential dissecting instrument to be used as a forceps;

FIG. 28 illustrates an exemplary differential dissecting member having a tissue-engaging surface and a side surface;

29A-29E illustrate enlarged views of the tissue engaging surface and side surfaces of the differential dissecting member of FIG. 28, the tissue engaging surface being comprised of a series of alternating valleys and protrusions;

FIG. 30 illustrates how the side surfaces of the differential dissecting members shown in FIGS. 28 and 29A-29C align and strain the tissue (including the interstitial fibrous component) and how straining the interstitial fibrous component facilitates aligning the interstitial fibrous component and causing them to enter the valleys and then be torn by the protrusions;

FIG. 31 further illustrates from a different angle how the fibrous components of the tissue enter the valleys and are then pulled taut by the protrusions and torn;

FIG. 32 shows an exploded view of a complete exemplary differential dissecting instrument;

33A-33C show enlarged views of the differential dissecting member of the differential dissecting instrument of FIG. 32, with emphasis on how the scotch yoke mechanism causes the rotating shaft to drive the differential dissecting member in reciprocating oscillation;

FIG. 34 illustrates an exploded view of another exemplary differential dissecting instrument with retractable blades;

35A-35C show enlarged views of the differential dissecting members of the differential dissecting instrument of FIG. 34, including how the mechanism may also be used to vary the amplitude of oscillation of the differential dissecting members;

36A-36B illustrate an exemplary retractable blade that is a retractable hook with a more aggressive tissue engaging surface and a hook with a sharp bend that allows tissue to be selectively sliced for sharp dissection;

FIG. 37 illustrates how the retractable hook shown in FIGS. 36A and 36B can be used to quickly and safely sever a membrane structure such as the peritoneum;

FIG. 38 illustrates a complete exemplary differential dissecting instrument having a pistol grip and that can rotate the instrument insertion tube, thereby rotationally rotating the plane of oscillation of the differential dissecting member;

fig. 39 shows how an exemplary differential dissecting instrument may fit with the arm of a surgical robot and (optionally) with a conductive pad for electrocautery; and

FIG. 40 illustrates an exemplary laparoscopic version of the differential dissecting instrument with an electromechanical actuator distal to the joint.

Detailed Description

Embodiments disclosed herein include methods and devices for blunt dissection that differentially disrupt soft tissue but not hard tissue. In particular, in one embodiment, a differential dissecting instrument for differentially dissecting complex tissue is disclosed. The differential dissecting instrument includes a handle and an elongated member having a first end and a second end, wherein the first end is connected to the handle. The differential dissecting instrument further comprises a differential dissecting member configured to be rotatably attached to the second end, the differential dissecting member comprising at least one tissue engaging surface. The differential dissecting instrument further comprises a mechanism configured to mechanically rotate the differential dissecting member about an axis of rotation to thereby move the at least one tissue-engaging surface in at least one direction against the composite tissue. The at least one tissue engaging surface is configured to selectively engage the composite tissue such that, upon pressing the differential dissecting member into the composite tissue, the at least one tissue engaging surface moves across the composite tissue and the at least one tissue engaging surface disrupts at least one soft tissue in the composite tissue, but does not disrupt hard tissue in the composite tissue.

In another embodiment, a differential dissecting member for dissecting complex tissue is disclosed. The differential dissecting member includes a body having a first end and a second end with a central axis from the first end to the second end. The first end is configured to be oriented away from the complex tissue and configured to engage a drive mechanism that moves the differential dissecting member, thereby sweeping the second end in a direction of motion. The second end includes a tissue-facing surface configured to be oriented toward the composite tissue. The tissue-facing surface includes at least one tissue-engaging surface comprised of a series of at least one valley and at least one protrusion staggered along the direction of motion on the tissue-facing surface such that an intersection of the at least one valley and at least one protrusion defines at least one valley edge having a directional component perpendicular to the direction of motion. In one embodiment, the at least one valley edge is not sharp.

In particular, a "differential dissecting instrument" is disclosed. The term "differential" is used because differential dissecting instruments can destroy soft tissue but avoid destroying hard tissue. The effector end of the differential dissecting instrument may be pressed against tissue consisting of hard and soft tissue, and soft tissue is far more easily damaged than hard tissue. Thus, when the differential dissecting instrument is pressed into the composite tissue, the differential dissecting instrument disrupts the soft tissue, thereby exposing the hard tissue. This differential action is automatic, which is a function of the device design. Requiring much less attention from the operator than traditional blunt dissection methods and greatly reducing the risk of accidental tissue damage.

For purposes of this application, "soft tissue" is defined as various soft tissues that are separated, torn, removed, or otherwise typically destroyed during blunt dissection. "target tissue" is defined as tissue that needs to be isolated and left intact in a blunt dissection, such as a blood vessel, gallbladder, urethra, or nerve bundle. "hard tissue" is defined as a mechanically strong tissue, typically comprising one or more layers of tightly aggregated collagen or other extracellular fibrous matrix. Examples of hard tissue include vessel walls, nerve fiber sheaths, fascia, tendons, ligaments, bladder, pericardium, and many others. A "complex tissue" is a tissue composed of soft and hard tissues and may contain a target tissue.

Fig. 3A, 3B, and 3C illustrate effector ends of a differential dissecting instrument 300 that may differentially disrupt soft tissue but not hard tissue. In this embodiment, the dissection member comprises a dissection wheel 310 that rotates about a shaft 320, the shaft 320 being held within a cavity 331 inside a shroud 330. Figure 3A shows the separated parts. Fig. 3B and 3C show two different views of the assembly. The dissection wheel 310 is rotated by any of a variety of mechanisms, such as a motor or a manually driven driver with a suitable transmission. The dissection wheel 310 has a tissue engagement surface 340 that can grasp and disrupt soft tissue without disrupting hard tissue. Examples of tissue engaging surfaces 340 and dissecting wheel 310 include a diamond wheel or grindstone or a surface otherwise covered by small protrusions or protuberances (as further defined below) of the protruding surface. The shroud 330 covers portions of the dissection wheel 310, exposing only a portion of the dissection wheel 310. In use, the dissection wheel 310 rotates at a speed in a range from about sixty (60) rpm to about twenty-five thousand (25,000) rpm, or from about sixty (60) rpm to about one hundred thousand (100,000) rpm, which may be selected by an operator. In addition, the direction of rotation of the dissection wheel 310 may be turned by the operator. Alternatively, in one embodiment, the dissection wheel 310 may oscillate (reciprocate) at a frequency in a range from about sixty (60) to about twenty thousand (20,000) cycles per minute. In another embodiment, the dissection wheel 310 may oscillate (oscillate back and forth) at a frequency in a range from about 2,000 to 1,000,000 cycles per minute.

The dissection wheel 310 is one example of a differential dissection member (hereinafter "DDM") that can differentially disrupt soft tissue but not hard tissue. For clarity, FIG. 3D illustrates a side, front, and oblique view of one embodiment of the DDM350 that has been separated from the remainder of the differential dissecting instrument 300. The DDM350 is comprised of a body 360 having an axis of rotation 365 about which the body 360 rotates. The rotation may be oscillating (i.e., back and forth) or continuous. The outer surface 361 of the body 360 has a tissue engaging surface 370 distributed over at least a portion of the outer surface 361 of the body 360. Non-tissue engaging surface 371 is the portion of outer surface 361 not covered by tissue engaging surface 370. In this embodiment, no portion of the outer surface 361 that contacts tissue, particularly the tissue engaging surface 370, should have characteristics that are sharp enough to slice tissue, and thus, there should be no cutting edge (e.g., a scalpel or surgical shears), no sharp teeth (e.g., a saw), no sharp corners, and no cutting slot with a sharp edge (e.g., a drill or arthroscopic scraper), where "sharp" refers to having a radius of curvature of less than 25 m. Typical maximum dimensions of a DDM are between about three (3) and about twenty (20) millimeters (mm). Alternatively, the microsurgery may measure between about two (2) mm and about five (5) mm.

The tissue engaging surface 370 is further defined by a plurality of protrusions 375 (shown in the enlarged detail view of fig. 3D) protruding from the outer surface 361 of the body 360, each protrusion 375 having a protrusion length 380 from trough to crest measured in a direction generally perpendicular to the localized area of the outer surface 361 of the body 360. The different protrusions 375 on the tissue engaging surface 370 may all have the same protrusion length 380, or they may have different protrusion lengths 380. The protrusion 375 preferably has a protrusion length 380 of less than about one (1) mm. Alternatively, for certain embodiments, the protrusion length may be greater than about one (1) mm and less than about five (5) mm. In general, all of the protrusions 375 on the tissue engaging surface 370 have an average protrusion length (P)_avg). The protrusions 375 are separated by a gap 385 preferably spanning a distance of about 0.1 mm to about ten (10) mm.

Alternatively, body 360 shown in FIG. 3D may be shaped such that tissue engaging surface 370 is located at different distances from rotational axis 365. Thus, placement radius R may be the distance from axis of rotation 365 to any point on tissue engaging surface 370, measured on a plane perpendicular to axis of rotation 365. Thus, there will be a minimum placement radius R having the shortest length_minAnd a maximum placement radius R having a longest length_maxAs shown in figures 3D and 3E, R is provided that the tissue engaging surface 370 does not completely cover the surface 361 of the DDM350_minAre both greater than zero. Thus, if body 360 is shaped such that tissue engaging surface 370 is located at different distances from axis of rotation 365, (R) is_max-R_min) Greater than zero. In certain embodiments of DDM, the relationship (R)_max-R_min) Greater than about one (1) mm. In other embodiments, the relationship (R)_max-R_min) Greater than P_avg. Alternatively, as shown in the examples in fig. 3D and 3E, R_minGeneral ratio R_maxAt least 5% shorter. Typical size of DDM is R_minGreater than about one (1) mm and R_max<About fifty (50) mm; however, a small form for microdissection may have R_min> about 0.5 mm and R_max<A smaller dimension of about five (5) mm.

Referring now to FIG. 3E, four different embodiments of a DDM are shown in side view, with the axis of rotation 365 perpendicular to the plane of the page. The cross-sectional profile of the DDM in a plane perpendicular to the axis of rotation 365 is important as will be discussed in subsequent paragraphs. The following are four scenarios of cross-sectional profiles of DDMs.

DDM type I: the cross-sectional profile may be any shape other than circular or rounded wedge. The axis of rotation 365 is located at any point within the cross-section shown in FIG. 3D, thereby creating P_avg<(R_max-R_min) The result of (1). As shown in fig. 3D, DDM type I may include regular cross-sectional profiles and irregular cross-sectional profiles, including various asymmetric, wavy/undulating/scalloped boundaries, openings, involute boundaries, and the like. In the present example, DDM type I oscillates back and forth between two end positions (dashed outline). Alternatively, the movement may be rotational.

DDM type II: the cross-sectional profile is circular or a circular wedge. The axis of rotation 365 is located at any point within the cross-section, thereby producing P_avg<(R_max-R_min) As a result of (i.e., the axis of rotation 365 is not near the center of the circle).

DDM type III: the cross-sectional shape is circular or a circular wedge. The axis of rotation 365 is located at any point within the cross-section sufficiently close to the center of the circle to produce P_avg~ (R_max-R_min) As a result of (i.e., the axis of rotation 365 is approximately at the center of the circle).

DDM type IV: the cross-sectional shape has features that repeat regularly over the perimeter, such as scalloping, thereby producing P wherever the axis of rotation 365 is located (including at the centroid of the cross-sectional shape)_avg<(R_max-R_min) The result of (1). DDM classType I and DDM type IV are closely related, so that the axis of rotation 365 can be located anywhere within the cross-sectional shape and still produce P_avg<(R_max-R_min) The result of (1).

The scalloping, undulating, or any regular repeating features of the DDM do not include perforations or holes in the tissue engaging surface 370, the perforated walls not significantly contacting the tissue. For example, the aspiration channel disclosed in U.S. patent No. 6,423,078 includes an aperture in the abrasive face (serving as the tissue engaging surface) of the abrasive member. These holes do not include the features disclosed for DDM because they serve only as fluid ports in the tissue engaging surface and the suction channel walls do not bear on the tissue. However, the DDMs disclosed herein may include a gettering channel, such as this type of gettering channel.

The DDMs of types I to IV may also comprise any kind of shape out of the plane of the page. As stated previously, "the cross-sectional profile of the DDM in a plane perpendicular to the axis of rotation 365 is important". Thus, the dissection wheel 310 shown in fig. 3A-3C is an example of DDM type III.

Figure 3F illustrates a DDM 390 similar to the DDM350 shown in figure 3D. The DDM 390 has a first end and a second end 392, wherein the first end 391 is distal from the complex tissue 399 and is rotatably engaged with a mechanism (not shown) such that the DDM 390 is rotated by the mechanism about the axis of rotation 365. The mechanism may include a motorized drive and a manual drive. Second end 392 points toward compound tissue 399 and comprises a semi-elliptical shape defined by three orthogonal half axes: a semi-major axis a, a first semi-minor axis B, and a second semi-minor axis C, wherein the semi-major axis a is in the direction of a line connecting the first end 391 and the second end 392; semi-minor axis C is parallel to axis of rotation 365 (i.e., a is perpendicular to axis of rotation 365); and, the semi-minor axis B is perpendicular to the semi-major axis a and the semi-minor axis C. The semi-ellipse can have a variety of shapes (e.g., there can be different relationships between the lengths of the three half-axes, including a = B = C, A ≠ B ≠ C, A > B and a > C). In one embodiment, A > B > C is very effective for DDM.

Fig. 4A-4C illustrate how the effector end of a differential dissecting instrument 300 may be used to dissect complex tissue, where the DDM is a dissecting wheel 310. In fig. 4A, prior to contacting tissue mass 400 or while contacting tissue mass 400, the operator initiates rotation of dissection wheel 310, as indicated by arrow 410. In fig. 4B, the operator then presses the exposed tissue engaging surface 340 of the dissection wheel 310 into the volume of composite tissue 400 for blunt dissection to reach the target tissue 420 within the volume. Arrows 430 and 440 in fig. 4B illustrate two possible operator-performed motions of the differential dissecting instrument 300. Only the portion of the tissue engaging surface 340 of the dissection wheel 310 exposed outside the shroud 330 contacts the tissue 400, thereby destroying the portion of the tissue 400 that is in contact with the tissue engaging surface 340. Because the exposed moving portion of tissue engaging surface 340 may damage tissue without further action by the surgeon (i.e., without the surgeon exerting force against tissue 400 with differential dissecting instrument 300), tissue may be damaged only by applying rotating dissecting surface 340 of dissecting wheel 310 to any portion of tissue 400; however, when the dissection wheel 310 contacts the hard tissue of the target tissue 420, the dissection wheel 310 does not damage the target tissue 420. Note that pushing the dissection wheel 310 into the tissue 400 as indicated by the arrow 430 is a "trap" -because the dissection wheel 310 does not damage hard tissue and therefore does not damage the target tissue 420, the dissection wheel 310 can be pushed non-penetratively into the tissue 400. Other motions of differential dissecting instrument 300 may be used for dissecting tissue 400, including motions orthogonal to arrows 430 and 440, curvilinear motions, and other 3D motions. Once the target tissue 420 is exposed, the differential dissecting instrument 300 may be retracted to expose the target tissue 420, as shown in FIG. 4C.

Figures 4D-4F illustrate how one embodiment of a DDM destroys soft tissue but does not destroy hard tissue. Fig. 4D depicts a cross-sectional view of a DDM as a dissection wheel 310, wherein the tissue engagement surface 340 has protrusions 375. The dissecting wheel 310 moves in and out of the plane of the page and the shaft 320 (not shown) is generally parallel to the plane of the page. Thus, the protrusion 375 moves across the plane of the page. Fig. 4D further illustrates the volume of soft tissue 400 that is substantially held in place as the dissection wheel 310, tissue engagement surface 340, and protrusion 375 travel through the plane of the page. The dissection wheel 310 disrupts the soft tissue 400, allowing for movement of the protrusion 375 relative to the substantially stationary soft tissue 400. In detail, the soft tissue 400 is composed of a fibrous component 401 and a gel-like material 402. (soft tissue is typically composed of extracellular material with fibrous components 401 (e.g., collagen fibers and bundles of small fibers) and sheet components (e.g., a thinner film dispersed in a water-swellable gel-like material)) the projections 375 can sweep over the gel-like material 402, causing them to encounter and then puncture the individual fibrous components 401 (e.g., at points 450 and 451); fibrous component 401 is then torn by relative movement of projections 375 on dissecting wheel 310 through the plane of the page and soft tissue 400. As the dissection wheel 310 is pushed deeper into the tissue 400, the protrusions 375 can puncture the deeper and deeper fibrous components and can also tear them. Thus, the DDM can be used to dissect soft tissue 400 having discrete components.

In contrast to fig. 4D, fig. 4E shows how closely packed fibrous tissue can resist dissection by the dissection wheel 310. Hard tissue 403 is typically composed of fiber components 401 that are closely packed in a parallel, staggered, or other organized array (e.g., fascia and vessel wall) or a closely packed 2D and 3D mesh, and a gel-like material 402 covers the array of fiber components 401. In fig. 4E, hard tissue 403 is composed of gel-like material 402 (dotted areas) thinly coated with a layer of tightly packed fibrous elements 401, the filaments of fibrous elements 401 being depicted with their long axes perpendicular to the plane of the page, thereby depicting the cross-section of fibrous elements 401 as circular. In this image, the dissection wheel 310 oscillates back and forth left and right across the page, as indicated by arrow 405, to sweep over the protrusion 375 on the surface of the hard tissue 403. Due to the close packing of the fibrous components 401 in this hard tissue 403, the protrusions 375 cannot individually engage and puncture the fibrous components 401, thereby not applying sufficient stress to tear the fibrous components 401. In addition, gel-like material 402 acts as a lubricant, allowing protrusions 375 to slide easily out of the tightly packed fibrous component 401 of hard tissue 403. Finally, any compliance of the surface of hard tissue 403 exposed to dissecting wheel 310 prevents tension from developing in hard tissue 403 or fibrous component 401, causing hard tissue 403 to deflect from any pressure exerted by dissecting wheel 310. Thus, the hard tissue 403 combines the close packing of the fibrous and sheet-like elements 401, lubrication of these elements by the gel-like material 402, and compliance of the hard tissue 403 to resist dissection of the DDM.

As mentioned above, the motion of the DDM may be rotational or oscillatory. The speed with which a point on the DDM passes through a particular region of tissue greatly affects the ability of the DDM to destroy the tissue. Fig. 4F depicts the dissection wheel 310 sweeping left and right in the plane of the page (as shown by double headed arrow 460) on the soft tissue 400 with contact point 470. The translation speed of the contact point 470 is determined by the rotation speed of the DDM and the distance 480 separating the contact point 470 from the center of rotation (not shown). For rotational motion, the translation speed is equal to 2 π D ω, where D is the distance 480 and ω is the rotational frequency in revolutions per second. For oscillatory motion, the translation speed is equal to D Ψ 2 β, where D is distance 480, Ψ is the oscillation frequency in cycles per second, and X is the sweep angle in arc meters. For differential dissectors, distance 480 ranges from about one (1) mm to about forty (40) mm; the range of rotational speeds is from about two (2) revolutions per second to about three hundred fifty (350) revolutions per second; the oscillation frequency ranges from about two (2 hertz) to about three hundred fifty (350) Hz; and the sweep angle ranges from 2 ° to 270 °. Thus, the translation speed of contact point 470 on the differential dissector may range from about one (1) mm per second to about sixty thousand (60,000) mm per second. In one embodiment, a distance 480 of about fifteen (15) mm and an oscillating motion with a frequency of about 2400 per second swept about forty-five degrees (45) at about one hundred (100) Hz is very effective for many soft tissues. Note that because the surgeon is careful during dissection and only moves his instrument slowly (typically much less than one hundred (100) mm per second), this means that the speed of the motion performed by the operator (as shown in figure 4) is always less than the speed of the contact points on the DDM during dissection. Further, the motion of the DDM is described throughout this document as starting from a rotational motion (either continuous rotation or reciprocating (i.e., back and forth) oscillation). However, as described above, any movement of the DDM relative to the tissue that causes the tissue-engaging surface of the DDM to properly engage the tissue (including linear movement) may be used.

DDM can abut against the vessel wall, pleura, pericardium, esophagus, gall bladder, and almost any other organ or tissue that is composed of or covered by tightly packed fibrous tissue, and under light hand pressure, DDM does not severely damage such hard tissue. In contrast, DDM can abut the mesentery or other soft tissue and the soft tissue can quickly break down upon gentle hand depression. The inventors have discovered that any of the various DDMs adapted differential dissectors as disclosed herein perform rapid dissection between the planes of the lung lobes in the lungs, dissect the intramammary arteries away from the inner wall of the chest, dissect the blood vessels and bronchioles in the lung ostia of the lung lobes, dissect the esophagus from the surrounding tissue, penetrate most of the muscle between fiber bundles but not the fiber bundles, dissect the fascia and tendons away from the muscle fibers, clean the fascia after dissection, expose the branched blood vessels and lymphatic structures, dissect the capsule into tissue, and dissect the tissue planes into many different tissues. Differential dissectors are versatile and have many potential uses. Importantly, due to the composition of the skin and surgical gloves, the skin and surgical gloves are not cut or otherwise damaged by the DDM, even when significant pressure is applied. Thus, the differential dissector itself is safe to use, which simplifies use during surgery, especially when the surgeon's fingers must be close to the dissection point.

The DDM is preferably formed of a rigid material, such as a metal or a rigid polymer (e.g., Shore a equal to or greater than 70), rather than a softer polymer and elastomer (e.g., Shore a less than 70). The use of a rigid material to keep the protruding airfoils protruding from the tissue engaging surface offset from the tissue can occur if softer materials are used. The DDM or component portions thereof can be machined from a bulk material, constructed via stereolithography, molded by any means known in the art (e.g., injection molding), or formed by any such method known in the art.

The protrusions of the tissue engaging surface of the DDM may be prepared in any of a variety of ways. The protrusions may be formed by coating the tissue engaging surface with a grit similar to that used for sandpaper, which grit is coarser than 1000 and finer than 10 according to the coated abrasive manufacturing Association standards. The grit may comprise diamond, silicon carbide, metal, glass, sand, or other materials known in the art. The protrusions may be formed into the surface of the material constituting the DDM by sanding, sandblasting, machining, chemical treatment, electrical discharge machining, or other methods known in the art. The protrusions may be molded directly into the surface of the DDM. The protrusions may be formed onto the surface by stereolithography. The shape of the protrusions may be irregular, such as sand particles, or the shape of the protrusions may be regular, with a defined faceted, curved or sloped surface. The protrusions may be elongated, and the long axes of the protrusions may be angled with respect to the tissue engaging surface. The protrusions possess a cross-sectional shape when the tissue engaging surface is viewed from above, and the shape may be rounded, faceted, or compound. The cross-sectional shape of the protrusions may be oriented relative to the direction of travel of the DDM.

Keeping the tissue moist helps to perform differential dissection. Fully wetted hard tissue lubricates better and greatly reduces damage from DDM. In contrast, the soft tissue, which is sufficiently wet, remains water-swollen and soft, thereby separating the spacing of the individual fibers, facilitating their engagement and tearing by the projections protruding from the tissue-engaging surface of the DDM. Moistening the tissue can be achieved in one of a number of ways, including: the tissue is simply irrigated with saline during dissection. Irrigation may be performed using procedures already used in surgery, such as irrigation lines, or by one of the devices discussed below. In addition, wetting the tissue and thus the tissue engaging surface of the DDM reduces the clogging of the tissue engaging surface by the disrupted tissue.

Fig. 5A and 5B illustrate another embodiment of an effector end of a differential dissecting instrument 500, the differential dissecting instrument 500 having a DDM type III configured as a cylinder 510. Fig. 5A shows a cylinder 510 with a shaft 520 separated from a shroud 530. Tissue engaging surface 540 covers one side of cylinder 510. The double arrow indicates rotation about the rotation axis 575. Fig. 5B shows two portions configured for use with only a limited portion of the tissue engaging surface 540 that is exposed.

Fig. 5C shows another embodiment of the effector end of a differential dissecting instrument with a shield and DDM having different configurations (herein another DDM type III). The top view of fig. 5C shows the differential dissecting instrument 550 with the dissecting wheel 560, with the shaft 570 separated from the shroud 580. The tissue engaging surface 590 covers the circumference of the dissection wheel 560. The double arrow indicates the rotation axis 575. The bottom view of fig. 5C shows two portions configured for use with only a limited portion of the tissue engaging surface 590 being exposed. This configuration is problematic because the shield 580 makes it difficult to position the tissue engaging surface 590 in abutment with the tissue, and the shield 580 blocks the operator's view.

FIG. 6A illustrates one embodiment of a differential dissecting instrument 600 that includes a handle 610 for use by an operator. The handle 610 is attached to an elongated member 620, the elongated member 620 including a first end 621 attached to the handle 610 and a second end 622 attached to the DDM 630. The elongated member 620 may be shorter to enable better manual control of the DDM630 over instruments used for open surgery, or the elongated member 620 may be longer to enable the differential dissecting instrument 600 to be used as a laparoscopic instrument. The drive mechanism for rotating the DDM630 (such as a rotary drive shaft for a scotch yoke or crank/slide) is readily adaptable to any elongated member 620, long or short, or any device capable of driving the DDM 630. The DDM630 is a type III DDM rotatably mounted to the elongated member 620 at the second end 622, thereby causing the DDM630 to oscillate back and forth about its axis of rotation 640, as indicated by the double arrow (in fig. 6A, the axis of rotation 640 is perpendicular to the plane of the page). The first end 621 and the second end 622 define a centerline 650 of the elongate member 620. As the centerline 650 approaches the second point 622, a tangent 651 to the centerline 650 and the axis of rotation 640 thereby define a presentation angle 670 (not shown, perpendicular to the page). In the present example, the presentation angle 670 is 90 ° (i.e., the axis of rotation 640 is aligned perpendicular to the tangent 651). The first end 621 of the elongate member 620 (rather than the handle 610) may be attached to a robotic arm of a robot for robotic surgery. The DDM may be easily adapted to any other means that enables the DDM to be moved or rotated.

FIG. 6B illustrates another embodiment of a similar differential dissecting instrument 601, but with the axis of rotation parallel to the centerline. The handle 610 is attached to an elongated member 620, the elongated member 620 including a first end 621 attached to the handle 610 and a second end 622 attached to the type IIIDDM 631. The DDM631 is rotatably mounted to the elongate member 620 at the second end 622, thereby causing the DDM631 to oscillate back and forth about its axis of rotation 640. In fig. 6B, the rotation axis 640 is parallel to the plane of the page. As the centerline 650 approaches the second end 622, the first end 621 and the second end 622 define a centerline 650 of the elongated member 620 with a tangent line 651. The axis of rotation 640 is thus aligned parallel to the tangent line 651 (i.e., the angle of presentation 670 is 0 °). (again, the presentation angle 670 is not shown in FIG. 6B because the presentation angle is 0 °) the differential dissecting instrument 601 is thus similar to the differential dissecting instrument 550 of FIG. 5C and thus has similar limitations, including: it is difficult to position the tissue engaging surface of the DDM631 in abutment with tissue without blocking the operator's line of sight.

Fig. 6C illustrates another embodiment of the differential dissecting instrument 603 with a curved elongated member 620, the curved elongated member 620 having a curved centerline 650 and a tangent 651 to the centerline 650 as the centerline 650 approaches the second point 622. The axis of rotation 640 is perpendicular to a tangent 651 forming a presentation angle 670, which presentation angle 670 is 90 ° in this example. The elongated member 620 may be similarly bent, joined, hinged, or otherwise made of multiple parts. In all cases, the presentation angle 670 is formed by the axis of rotation of the DDM and the tangent to the centerline as it approaches the second point 622.

FIG. 6D illustrates another embodiment of a differential dissecting instrument 604 similar to differential dissecting instrument 602 in FIG. 6B. The handle 610 is attached to an elongated member 620, the elongated member 620 including a first end 621 attached to the handle 610 and a second end 622 attached to a type III DDM 631. The DDM631 is rotatably mounted to the elongate member 620 at the second end 622, thereby causing the DDM631 to oscillate back and forth about its axis of rotation 640. In fig. 6B, the rotation axis 640 is parallel to the plane of the page. As the centerline 650 approaches the second point 622, the first end 621 and the second end 622 define a centerline 650 of the elongated member 620 with the tangent line 651. The axis of rotation 640 is thus non-zero aligned with the tangent line 651 (i.e., the presentation angle 670 is between 0 ° and 90 °). In a preferred embodiment, presentation angle 670 is not equal to 0 ° for the reasons described for differential dissecting instrument 603 in fig. 5C and 6B.

Fig. 7A and 7B illustrate another embodiment of the effector end of a differential dissecting instrument 700 using an dissection line 710 as a DDM. Fig. 7A shows the assembled device. The dissection line 710 is spaced a distance 725 from the backing surface 726 of the shield 730, the dissection line 710 exiting the first post 720, crossing the gap 722 and entering the second post 721 at the end of the shield 730. The exploded line 710 is a continuous loop line that is driven so that the exposed portion of the exploded line 710 travels in the direction indicated by arrow 723 across the gap 722 in fig. 7A.

FIG. 7B shows a schematic side view of this embodiment of a differential dissecting instrument 700 depicting the loop wire and drive mechanism of dissection line 710. The exploded line 710 is a continuous loop that passes over a first idler bearing 750 built into the first column 720 and then out of the first column 720. The dissection line 710 travels across the gap 722, moves in the direction of arrow 723, and enters the second post 721 where the dissection line 710 passes over the second idler bearing 751. The loop of the exploded line 710 is further retracted into the shield 730 where it passes over a drive wheel 760, the drive wheel 760 being rotated by a motor, for example, in the direction of the curved arrow 724. Thus, rotation of drive wheel 760 drives dissection line 710. Note that the dissection line 710 may be a flexible linear element having any cross-sectional shape, so instead of a line having a circular cross-sectional shape, the dissection line 710 may be a flexible flat strip having a tissue engaging surface towards the outside. Similarly, dissection wire 710 may be a flexible cord having a diameter larger than the wire that may be allowed to flip over idler bearings 750 and 751; the flexible cord has a tissue engaging surface. Further, the distance 725 between the dissection line 710 and the backing surface 726 may be arbitrarily large or small, for example, the distance 725 may be large enough to create a large area enclosed by the dissection line 710, the backing surface 726, and the first and second cylinders 720, 721, thereby enabling enclosure of the target tissue to be removed. Conversely, the distance 725 may be zero, in which case the dissection line 710 extends along the surface of the shield 730, or even in a tiny slot that supports the dissection line 710 from behind. The receiving channel may have a semi-circular cross-sectional shape, thereby exposing only a portion of the cross-sectional shape of the dissection line 710 to the tissue to be dissected. Further, the backing surface 726 may be flat in shape, or the backing surface 726 may be curved, slender or stout, and the curved surface may possess convex regions, concave regions, or a combination.

Fig. 8A-8C illustrate the effector end of a differential dissecting instrument 800 using a flexible band as the DDM. Fig. 8A shows the separated parts. Flexible band 840 has an outer tissue engaging surface 850. Flexible belt 840 travels over idler 810, which idler 810 rotates about axis 820, all of which are housed in shroud 830.

FIG. 8B shows the effector end of differential dissecting instrument 800 after assembly, exposing only a limited portion of tissue engaging surface 850 of flexible band 840.

Fig. 8C shows a schematic top view of one example of how a flexible band (such as flexible band 840) may be driven. The idler wheel 810 and the drive wheel 860 are mounted inside the shroud 830. A flexible band 840 encircles idler 810 and drive wheel 860. Drive wheel 860 is electrically rotated, thereby causing flexible band 840 to be driven in the direction indicated by curved arrow 870. Tissue is then disrupted using the tissue engaging surface 850 exposed on the exterior of the shield 830. Drive wheel 860 may be driven by any of a variety of mechanisms, such as a motor, hand crank, or the like. The drive wheel 860 and idler wheel 810 need not be right circular cylinders, nor need their axes of rotation be parallel.

The tissue engaging surface may be exposed to the exterior of the shield to a greater or lesser extent than shown in the previous examples. In fact, the difference in exposure changes various aspects of the behavior of the differential dissecting instrument.

Preferably, the greater exposure increases the exposed area of the tissue engaging surface, which increases the amount of tissue destroyed per unit time and increases the surface area of tissue removed. Thus, reducing the exposure makes tissue removal more accurate, but reduces the total amount of material removed. Second, increasing the exposure changes the angle of the exposed tissue engaging surface. Referring to fig. 9A-9C, there are shown schematic top views of the effector end of differential dissecting instrument 800 with sequential constraints on the exposure of the tissue engaging surface 850 controlled by the aperture 900 in the shield. The aperture 900 is largest in fig. 9A and smallest in fig. 9C. The angular extent of the arrow perpendicular to tissue engaging surface 850 decreases due to the limited degree of exposure. In FIG. 9A, tissue engaging surface 850 is broken anteriorly and laterally. In fig. 9C, tissue engaging surface 850 is only broken forward. Thus, when tissue engaging surface 850 is applied to tissue, a different contact direction is applied depending on the angle of the exposed tissue engaging surface.

Second, this increase in the exposure angle of the tissue engaging surface 850 also changes the tension angle of the contacted surface of the tissue and the torque on the instrument. Turning to fig. 10A-10C, friction on tissue 400 by application of tissue engaging surface 1010 is illustrated.

In fig. 10A, tissue engaging surface 1010 is moving in the direction of arrow 1020. This creates a frictional force in the direction of arrow 1030. The larger the contact area, the greater the friction. The frictional force pulls tissue 400 sideways (in the direction of arrow 1030) shearing tissue 400 and pushing tissue engaging surface 1010 in the direction opposite arrow 1020. If the tissue engaging surface 1010 is mounted on the instrument 1060 at a distance from the point 1040 held by the operator, then the friction places a torque 1050 about the point 1040. This torque may pull the end 1070 opposite the point 1040 of the instrument 1060 away from the desired point of application, making anatomical control more difficult. Thus, limiting the exposure of the tissue engaging surface reduces friction and improves control by reducing torque on the handle.

Fig. 10B illustrates how rounded tissue engaging surface 850 creates a frictional force perpendicular to tissue engaging surface 850 and thus depends on the extent of contact of tissue 400 on rounded tissue engaging surface 850 in different directions. The resulting multi-directional shear forces on the tissue 400 produce a more complex strain pattern in the tissue 400. As shown in fig. 10A, the frictional force still produces a net upward force 1080 on the tip of the shroud 830; however, no net left/right (into and out of tissue 400) force is generated on the tip of the shield 830. Fig. 10C illustrates that the strain pattern in the tissue is simplified by narrowing the aperture 900 to reduce the exposure of the tissue engaging surface 850 to more than one dimension of friction on the tissue.

While this discussion of friction is for tissue, as described above with respect to wet tissue, the DDM described herein has exceptional qualities that are also effective when it has low friction with respect to complex tissue. Even with sufficient soaking of the entire DDM with a lubricant (such as a surgical lubricant or a hydrogel lubricant), the non-tissue engaging and tissue engaging surfaces remain effective.

During surgery, it is preferable to minimize the accidental delivery of tissue to other parts of the body. Tissue disruptors can be attached to the tissue engaging surfaces of the differential dissecting instruments disclosed herein. Accidental delivery can be minimized in two ways. First, narrowing and controlling the shape of the aperture 900 as shown in fig. 10B and 10C means that damaging tissue debris adhering to the tissue engaging surface 850 can only be transported a short distance before being deposited onto or into the shield. Similarly, if a damaging tissue fragment adheres to tissue engaging surface 850 and is then thrown tangentially away from tissue engaging surface 850 under the influence of inertia, narrowing aperture 900 reduces the surface area available for adhesion, the time available for adhesion, and the distance over which the material can be accelerated. Second, tissue engaging surface 850 may be made resistant to tissue attachment. Surface treatment of the tissue engaging surface 850 may be accomplished by any of a variety of techniques known in the art, such as chemical treatment, vapor deposition, sputtering, and other techniques. For example, fluorination of tissue engaging surface 850 by any of a variety of known methods (e.g., dip coating, chemical deposition, chemical crosslinking (e.g., with silanes), etc.) may render tissue engaging surface 850 resistant to tissue attachment by hydrophilic materials and carbon-based hydrophobic tissue components. In one embodiment, diamond/carbide coated tissue engaging surfaces may be used, which has been found to be less prone to tissue adhesion to these surfaces.

Material transport can also be reduced by using oscillating (reciprocating) motion of the DDM instead of a discontinuous unidirectional motion or a continuous rotational motion. The oscillation prevents transport over a distance exceeding the oscillation distance, which can only be in the range of a few rotation angles (e.g. 5 ° to 90 °). Any of a number of mechanisms may be used to drive the reciprocating oscillating motion with the rotary motor, such as a scotch yoke or a crank/slide.

Tissue apposition is also a problem for reducing the effectiveness of the tissue engaging surface 850. The occlusion of the tissue engaging surface 850 creates a thick coating of material over the tissue engaging surface 850, thereby reducing its effectiveness in ablating soft tissue. As above, making the surface resistant to tissue adhesion reduces this problem. Fluorinated tissue engaging surfaces and diamond/carbide tissue engaging surfaces are not easily clogged, especially when destroying adipose tissue.

If the tissue is wetted, further, if the tissue engaging surface 850 is flushed with water, the blockage is also reduced, as discussed earlier. Fig. 11A and 11B illustrate the differential dissecting instrument 1100 with a first array of three water outlets 1111 exiting the shroud 830 alongside the tissue engaging surface 850. A second array of three water outlets 1112 discharges water on an opposite side of the tissue engaging surface 850. Other outlet arrangements are possible. FIG. 11A shows a solid model in an oblique view. FIG. 11B shows a schematic top view of differential dissecting instrument 1100 with water or other fluid (such as saline) carried inside water tube 1121 and carrying the water to one side of shield 830 to water outlet 1111, and with a fluid carried inside second water tube 1122 and carrying the fluid to the other side of shield 830 to water outlet 1112. Water outlets 1111 and 1112 exit from opposite sides of aperture 900, providing fluid to both sides of tissue engaging surface 850. The liquid exiting the outlet may (optionally) carry a physiologically active material, whether dissolved in the liquid or suspended in the liquid. Physiologically active materials can include various pharmaceutical compounds (antibiotics, anti-inflammatories, etc.) and active biomolecules (e.g., cytokines, collagenases, etc.).

Proper placement of the tissue engaging surface 850 creates a frictional force on the tissue that can be used to advantage during blunt dissection. FIG. 12 illustrates a differential dissecting instrument 1200 having two opposing flexible straps 1201 and 1202 exposed in an aperture 1230. The various belts are configured as shown in fig. 10B, with flexible belt 1201 extending over idler 1211 and flexible belt 1202 extending over idler 1212, however, flexible belts 1201 and 1202 circulate relative to each other. Thus, flexible tape 1201 and flexible tape 1202 extend side-by-side in the same direction as shown by arrows 1203 and 1204, but, when exposed to tissue 1205, extend in opposite directions as shown by arrows 1271 and 1272. Thus, flexible strap 1201 creates a net downward force 1251 on shield 1220, while flexible strap 1202 creates a net upward force 1252 on shield 1220, with these forces 1251 and 1252 thereby canceling out, leaving little or no net force on shield 1220. This eliminates any twisting of the differential dissecting instrument 1200 (as depicted in FIG. 10A), making control easier for the operator. Furthermore, during dissection, the opposing directions of motion 1271 and 1272 of flexible bands 1201 and 1202 create opposing frictional forces on tissue 1205, pulling tissue 1205 apart in the region identified by double arrow 1260. This pulling action may facilitate blunt dissection by tearing tissue in the region of double arrow 1260. Note that gap 1280 between flexible straps 1201 and 1202 inside shield 1220 may vary and may decrease to zero, thereby bringing flexible straps 1201 and 1202 into contact. Contact between flexible belts 1201 and 1202 may help match the drive mechanism to the travel rate of flexible belts 1201 and 1202. Indeed, friction between flexible straps 1201 and 1202 may enable one strap (e.g., 1201) to drive the other strap (1202 in this example). Thus, a motor may, for example, actively drive flexible belt 1201, and then flexible belt 1202 is driven by flexible belt 1201. This can simplify the drive mechanism for both belts.

FIG. 13 illustrates how the shield 1330 of the differential dissector instrument 1300 may house other items for enhanced functionality. The dissection wheel 810 is exposed at the aperture 900. Suction lines 1301 and 1302 may be attached to the front of shield 1330 near tissue engaging surface 850 to help remove any debris from the damaged or excess fluid, such as fluid from water tubes 1121 and 1122, which flows out through water outlets 1111 and 1112. Light Emitting Diodes (LEDs) may be placed on the shield 1330 to better illuminate the area undergoing blunt dissection; for example, LEDs 1311 and 1312 are powered through cables 1313 and 1314, respectively, and light from LEDs 1311 and 1312 illuminates tissue in the damaged area directly.

Fig. 14 illustrates how the elongate member 1410 of the differential dissecting instrument 1400 may articulate with bendable regions 1430 so that a user may achieve variable bending of the elongate member 1410 to facilitate placement of the DDM 1420. In position 1, the elongate member 1410 is straight. In positions 2 and 3, the elongate member 1410 is sequentially bent at the bendable region 1430, thereby moving the DDM 1420 from forward in position 1 to sideways in position 3. Bendable region 1430 may be an articulating joint or any other mechanism to allow bending.

Fig. 15A through 15E show different DDMs illustrating various important dimensions and features of the DDMs. Figure 15A shows a top view of a DDM1500 rotating about a rotatable joint 1510. The DDM1500 is actuated to oscillate reciprocally up and down, as indicated by double arrow 1506, to cause the tissue engaging surface 1520 (pebble texture portion) to follow a radius R_ASwing through an arc. The oscillation of the DDM1500 can swing within a range of ± 90 degrees. The tissue engaging surface has a smallest radius R in the plane of rotation (the plane perpendicular to the plane of rotation (in this case the plane of the page))_S。

Fig. 15B shows a side view in cross section in two successive enlarged views. (in this view, DDM1500 thus oscillates in and out of the page.) first side 1530 and tissue engaging surface 1520 meet at first boundary 1540, having radius of curvature R_EAnd second side 1531 and tissue engaging surface 1520 meet at a second boundary 1541 having a radius of curvature R_EWhere the radii of curvature of first boundary 1540 and second boundary 1541 may be different, but should be large enough so that first boundary 1540 and second boundary 1541 are not sharp. Then, a maximum length L is created by protrusion 1550 toward tissue engaging surface 1520_maxDefined as the maximum length of a feature from the innermost trough to the outermost peak.

Figure 15C illustrates a different DDM 1501 having a scalloped tissue engaging surface formed by surface features 1560. Herein, surface features 1560 are lobes, however, surface features 1560 may be on tissue engaging surface 1520 with a minimum radius of curvature R_sAny regular or repeating features of (a). Also, the surface features may have contours that are not in the plane of rotation, as shown in fig. 15D and 15E. Fig. 15D shows an oblique view, while fig. 15E shows an end view. The inset in figure 15E shows a sequential enlarged cross-section of the DDM 1502 taken along a 45 ° angle. The DDM 1502 has surface features 1570, the profile of which 1570 lies in a plane 45 ° to the plane of rotation. As with the DDM 1501 in FIG. 15C, the organization of the DDM 1502The engagement surface 1520 has a maximum length of presence L_maxThe projection 1550. In one embodiment, R_AMay be between about one (1) mm and about one hundred (100) mm. In one embodiment, R_SAnd may be between about 0.1 mm and about ten (10) mm. In one embodiment, R_EMay be between about 0.05mm and about ten (10) mm so as not to present any slice edges to the tissue. Alternatively, for certain embodiments of DDM, R_SAnd R_EAnd may be as small as about 0.025 mm.

The DDM may have a scalloped or notched or contoured tissue engaging surface such that the angle of attack of the tissue engaging surface relative to the tissue surface varies as the tissue engaging surface passes over a given point in the tissue. In fact, for satisfying P_avg<(R_max-R_min) Any DDM of (e.g., DDM type I, type II, or type IV) is different in angle of attack. Different angles of attack make the anatomical action more aggressive, with more aggressive DDMs being more able to destroy harder tissue, while less aggressive DDMs are less able to destroy the same tissue.

Figure 16 shows an alternative arrangement where DDMs can be made to have different attack levels, i.e. the aggressiveness of the DDM can be designed. The DDM 1600 rotates about an axis of rotation 1610 and has a tissue engaging surface 1620 that supports protrusions 1620. These protrusions have a sharper tip (but still not sharp enough to slice). The DDM 1640 has a tissue engaging surface 1650 that supports protrusions having a more rounded tip 1652. The DDM 1680 has a tissue engaging surface 1690 that supports protrusions having an even more rounded tip 1692. DDM 1600 is more aggressive than DDM 1640, whereas DDM 1640 is more aggressive than DDM 1680.

Figure 17A illustrates one embodiment of a DDM 1700 having a scalloped tissue engaging surface 1710 and a center of rotation 1720. Thus, the DDM 1700 is an example of a DDM type IV. The back and forth oscillation of DDM 1700, as indicated by double arrow 1730, moves tissue engaging surface 1710 over tissue such that the scalloped edges support tissue engaging surface 1710 at different angles of attack as the respective scallops pass over the tissue.

Figure 17B illustrates the action of the DDM 1700 abutting the tissue 1750. Two points P on the tissue engaging surface 1710₁And P₂The angle of attack (angle θ between the direction of motion and the tangent to tissue engaging surface 1710 at the point of contact) is shown. Theta₁Less than theta₂. A similar action can also be achieved with DDM 1800 by using a circular tissue-engaging member 1805 having a tissue-engaging surface 1810 and a center of rotation 1820 that is not the center of the circular tissue-engaging member 1805 (e.g., DDM type II), as shown in fig. 18. The back and forth oscillation of the circular tissue engaging member 1805 as indicated by the double arrow 1830 moves the tissue engaging surface 1810 over the tissue, thereby moving the tissue engaging surface 1810 such that the angle of attack differs at various points on the circumference of the circular tissue engaging member 1805 at the tissue engaging surface 1810.

Figure 18 illustrates another point, particularly for accelerating the motion of the DDM against the tissue 1850, and acceleration occurs whenever loading or unloading the DDM and whenever the oscillating DDM decelerates after sweeping one direction and accelerates to sweep the opposite direction. The DDM 1800 is mounted such that its center of gravity 1870 is moved away from the center of rotation 1820. Solid double arrow 1830 shows rotation about center of rotation 1820 and dashed double arrow 1840 shows movement of center of gravity 1870. The force that accelerates the mass of the DDM 1800 and the distance between the center of gravity 1870 and the center of rotation 1820 create a moment about the center of rotation 1820 that causes the differential dissector to vibrate. This moment can cause the handle of the differential dissector to which the DDM 1800 is attached to wobble. DDM consisting of a denser material makes the shaking even more severe. Thus, manufacturing the DDM from a less dense material (e.g., a rigid polymer rather than a metal) may be beneficial in reducing handle wobble. Instead, counter moments can be arranged by appropriately distributing the mass within the DDM to place the center of gravity at the axis of rotation.

The entire surface of the DDM may be the tissue junction. Alternatively, the selected surface portion may be tissue engagement. This may be advantageous to localize the anatomical effect to a region of the surface of the DDM (e.g., an anterior surface). 19A-19D illustrate a differential dissecting instrument 1900 having a DDM that is a dissecting wheel 1910 similar to the dissecting wheel illustrated in FIGS. 3A-3C; however, the tissue engaging surface is limited to a thin tissue engaging strip 1920 around the outer circumference of the dissection wheel 1910 that rotates about the axis of rotation 365. The remaining non-tissue engaging surface 1930, which includes the exposed surface disposed laterally to one side of the tissue engaging strip 1920 or to the dissecting wheel 1910, has a more smooth surface that is optionally glass-smooth, free of protrusions, or otherwise incapable of engaging fibers in tissue. Fig. 19B illustrates how the dissection wheel 1910 fits into the shroud 1940 and is pressed in direction 367 by an operator. As illustrated in fig. 19C, a non-tissue engaging surface 1930 that is smoother than tissue engaging strips 1920 reduces damage to tissue 1950 after it has been separated by tissue engaging strips 1920. As the dissector penetrates further into the tissue 1950 in the direction of the pressure 367, the shield 1940 further protects the tissue 1950 from damage by the dissecting wheel 1910.

Fig. 19D illustrates additional important actions of non-tissue engaging surface 1930 and shield 1940. When there is a component of motion 1901 into tissue 1950 in the direction of depression 367 (not shown herein) of differential dissecting instrument 1900, these wider portions (non-tissue engaging surface 1930 and shield 1940) of differential dissecting instrument 1900 force the portions that were most recently separated by tissue 1950 apart or wedge, thereby aligning and tensioning fibrous components 1980 of tissue 1950, placing them under tension, and aligning them perpendicular to the motion of tissue engaging strips 1920. This strain in fibrous component 1980 promotes the ability of the protrusions of tissue engaging material in tissue engaging strips 1920 to grasp and tear individual fibers.

As tissue engagement strips 1920 move past tissue 1950, in a direction perpendicular to the plane of the page (and thus out of the plane of the page), protrusions on tissue engagement strips 1920 therein disrupt tissue 1950, including: individual fibrous components 1980 (e.g., collagen or elastin fibers) of the tear tissue 1950. Such fibrous components 1980 often have irregular alignment (i.e., irregular orientation) in soft tissue. However, as tissue 1950 is destroyed, differential dissector instrument 1900 is pushed into tissue 1950 in the direction of the component of motion 1901, such that, as the remaining tissue engaging surface 1930 and shield 1940 are pushed into separated tissue 1950, they push tissue 1950 (including severed fibrous components 1990) aside in the direction of arrows 1960 and 1961, thereby aligning their previously irregularly oriented fibers and stretching the material at the point of contact of tissue engaging strip 1920. This localized strain region aligns and stretches (thereby pre-tensioning) uncut fibrous components 1980 in a direction perpendicular to the direction of motion of tissue engaging strip 1920, as indicated by double arrow 1970, facilitating their grasping and increasing the likelihood that they will be severed by the protrusion from tissue engaging strip 1920. If the non-tissue engaging surface 1930 and the shroud 1940 are angled relative to each other, they will act as wedges, as shown in fig. 19C and 19D, or even if they have a wider width than the tissue engaging surface 1910. In one embodiment, as depicted in fig. 3F, a semi-elliptical shape with the second semi-minor axis C occupying a substantial portion of the first semi-minor axis B (e.g., in one embodiment, where 0.2B < C < 0.8B) is an effective shape for wedging.

As described in the preceding paragraph, aligning fibers can greatly alter the manner in which DDM performs. Alignment can be achieved by the surgeon pulling the tissue in the appropriate direction by hand or a separate instrument. As described in the preceding paragraphs, alignment may be achieved by the DDM, by a smooth portion on the tissue engaging wheel (such as non-tissue engaging surface 1930 as in fig. 19C-19D), by a smooth shield (such as shield 1940 in fig. 19A-19D), or by a separate mechanism on the DDM.

FIG. 20 shows details of one form of disrupting a tissue segment in a human patient. A region of interest 2000 of the patient is depicted within the circular window, showing a cross-sectional view through two opposing volumes (i.e., tissue segment a as opposed to tissue segment B); the opposition occurs in a region 2010, which region 2010 is bridged by interstitial fibers 2012 and taut interstitial fibers 2015 and is further associated with broken interstitial fibers 2020. Also depicted within the circular window is DDM2030 having a tissue engaging surface 2034, the tissue engaging surface 2034 further having protrusions 2032 and a smooth non-tissue engaging surface 2033. In this figure, DDM2030 is reciprocated about axis 2036, thereby moving fiber engaging protrusions 2032 in and out of the plane of the page (i.e., reciprocally toward and away from the viewer).

Tissue segment a and tissue segment B each further have a tissue segment surface 2005 and a tissue segment surface 2006, respectively, tissue segment surface 2005 and tissue segment surface 2006 being comprised of relatively tightly packed fibers parallel to tissue segment surface 2005 and tissue segment surface 2006, thereby forming a film overlying tissue segment a and tissue segment B (e.g., tissue segments a and B comprise hard tissue). Surface 2005 of tissue segment a and surface 2006 of tissue segment B are also three-dimensional curves. Although these tissue segment surfaces 2005 and 2006 may not contact each other at every point, the tissue segment surfaces 2005 and 2006 do not meet in a region 2010 where the tissue segment surfaces 2005 and 2006 are locally and substantially parallel opposite each other, and are typically substantially in contact with each other.

In this region 2010, the tissue segment surface 2005 and the tissue segment surface 2006 are secured to one another by a population of relatively loose interstitial fibers 2012 extending substantially perpendicular to the two opposing tissue segment surfaces 2005 and 2006. The small amount of interstitial fibers 2012 may or may not be derived from (or be a component of) an amount of fibers comprising the more tightly packed textile surfaces (tissue segment surfaces 2005 and 2006). For example, a given fiber comprising a portion of the tissue segment surface 2005 may extend a distance along the surface before turning away and continuing across the region 2010, thereby becoming part of the population of interstitial fibers 2012, and further, may continue across the region 2010 to the tissue segment surface 2006 where the given fiber may rotate and weave therein, thereby becoming part of the population of fibers comprising the tissue segment surface 2006. Thus, the definition of interstitial fibers 2012 includes any fibers that span, bridge, cross, or otherwise connect (or are closely associated with) the tissue segment surface 2005 and the region 2010 where the tissue segment surface 2006 are in opposition. In one embodiment, the interstitial fibers 2012 can be the same type of fibers as the fibers comprising the tissue segment surfaces 2005 and 2006 of tissue segments a and B. In another embodiment, the interstitial fibers 2012 can be of different types and the interstitial fibers 2012 can be strongly or weakly bonded, directly or indirectly, to the tissue segment surface 2005 and the tissue segment surface 2006.

In each case, all of the fibers involved are mechanically capable of transmitting forces (via tension) along the surface of each individual tissue segment, or indirectly between two tissue segments, or both. For example, the state of tension of the interstitial fibers 2010 and fibers comprising tissue segment surfaces 2005 and 2006 depends on the forces acting on tissue segments a and B, e.g., when the smooth non-tissue engaging surface 2033 wedges in and forces the tissue segments apart in directions 1960 and 1961. For example, the fibers 2010 resist tensile strain caused by movement of the tissue segment surfaces 2005 relative to each other in the direction 1960 and the tissue segment surfaces 2006 in the direction 1961, and further, the resistance varies depending on the mechanical properties of the fibers. For example, if unstressed interstitial fibers 2012 are vertically aligned with the two opposing tissue segment surfaces 2005 and 2006, the distance between the tissue segments a and B may be increased (as indicated by arrow 2030) until the interstitial fibers 2010 first straighten up like taut interstitial fibers 2015, eventually the fibers may break off (fail), as indicated by broken interstitial fibers 2020. The most common type of fiber in humans is collagen, which has a strain at break of more than about 5% of its unstressed normal length. If tissue segment a and tissue segment B move apart as shown by arrow 2030, collagen fibers (in this context, unstressed interstitial fibers 2012) will first become taut (e.g., taut fibers 2015). If the two tissue segments a and B are moved further apart, the collagen fibers will stretch by about 5%. It is critical that at this point, if the tissue segment a moves about 5% further from the tissue segment B than taut, the taut interstitial fibers 2015 can break, or, if the taut fibers 2012 do not break, the tissue segment itself can crack, very harmful to the patient.

Since surgeons often must separate, dissect, or otherwise move tissue segments relative to one another to access various regions within a patient's body, the surgeon constantly tightens the fiber population equivalent to the interstitial fibers 2010 throughout the patient's body. Current practice requires that the interstitial fibers be sliced into one tissue segment free of each other or that the interstitial fibers be torn in their entirety by applying a blunt force with surgical scissors (by opening the jaws, forcing the tissue segments apart, thus tearing the interstitial fibers). A common complication is slicing into tissue segments while attempting to cut only the interstitial fibers via sharp dissection, or tearing smaller or larger portions of tissue segments while attempting blunt dissection of the interstitial fibers. Either way, first strain occurs to tighten the interstitial fibers 2010, then stretch them, and then tear them. The aforementioned consequences of tightly connecting the interstitial fibers 2010 to the tissue segment surfaces 2005 and 2006 (e.g., air leakage and lung segment bleeding) now become clear: the force required to break the interstitial fibers must be isolated without subjecting the entire tissue segment itself to the same force.

Embodiments of the differential dissecting instrument disclosed herein are specifically designed to: the impact via the smooth surface 2033 generates an initial separation motion of the opposing tissue segments a and B to isolate the forces on the fiber population, thereby exposing and tensioning (pre-tensioning) the individual interstitial fibers 2010, making these fibers more susceptible to breakage, taking full advantage of the opportunity provided by these now-tensioned interstitial fibers 2015, and further discreetly causing these fibers to meet, engage and transform into broken interstitial fibers 2020 by localized impact of the protrusions 2032 of the tissue engaging surface 2034 of the differential dissecting member 2030. In this way, a DDM with smooth-sided non-tissue engaging surfaces and/or shields can greatly improve the speed and efficiency of tissue dissection while limiting the dissection effect to only those fibers within the soft tissue connecting adjacent hard tissue regions and still retaining those hard tissues.

21A-21C illustrate another differential dissecting instrument 2100 that uses a very thin dissecting wheel 2110 as the DDM. Dissection wheel 2110 is nearly entirely encased in a shield 2120 to achieve a very thin tissue engaging surface 2009, the shield 2120 serving to protect, separate and pre-tension the tissue to be dissected, as shown in fig. 19D.

Fig. 21A shows a side view, while fig. 21B shows a front view. Dissection wheel 2110 is mounted on two cylinders via a rotation shaft 2135: a first cylinder 2130 and a second cylinder 2131 (see the side view of fig. 21B). Rotating shaft 2135 is free to rotate within first cylinder 2130 and second cylinder 2131, but is fixedly secured to dissection wheel 2110. Sprocket 2140 is also fixedly secured to shaft 2135. The sprocket 2140 is rotated by the drive belt 2150. Thus, a drive mechanism 2160 is created by the first and second cylinders 2130, 2131, the shaft 2135, the sprocket 2140, and the drive belt 2150 to rotate the dissection wheel 2110 inside the shroud 2120 in the direction of arrow 2161. Alternative drive mechanisms may be used and the motion may be rotary or oscillatory. First and second boundaries 2111 and 2112 of dissection wheel 2110 are preferably not sharp, as shown in the enlarged portion of fig. 21B. (first and second boundaries 2111 and 2112 are the same as first and second boundaries 1540 and 1541 in FIG. 15B.) sharp boundaries can break more aggressively than rounded boundaries. However, sharper boundaries may be used if more aggressive destruction or even destruction is desired. Furthermore, one boundary may be made sharper than the other if differential or destructive is desired. For example, the first boundary 2111 may be square or even sharp, while the second boundary 2112 may be rounded to achieve a more aggressive breach or breach to one side of the first boundary 2111.

Shroud 2012 nearly encloses dissecting wheel 2110, leaving only a small portion of dissecting wheel 2110 exposed as tissue engaging surface 2111, and forming a wedge angle ω that determines the strain on the tissue at the point of destruction of dissecting wheel 2110. As the DDM 2100 is pushed into tissue, the greater the wedge angle ω, the more tissue is strained. Figure 21C depicts the DDM 2100 with the shroud 2120 in four different positions. The shroud 2120 may be moved independently of the drive mechanism 2160 and the dissection wheel 2110, the shroud 2120 being movable in the direction of the double arrow 2190. Thus, in position 1, only a small portion of dissection wheel 2110 is exposed. In position 2, the shield 2120 has been moved in the direction of arrow 2191, leaving a smaller portion of the dissection wheel 2110 exposed and also creating a larger wedge angle ω. In position 3, the shield 2120 has been moved in the direction of arrow 2192, so that the shield 2120 completely encloses the dissection wheel 2110. Thus, the dissection wheel 2110 can no longer destroy tissue. In this position, the dissection wheel 2110 effectively acts as a smooth, flat, blunt probe. In position 4, the shroud 2120 has been moved in the direction of arrow 2193, increasing the exposure of the dissection wheel 2110 that is visible in position 1 or position 2 and decreasing the wedge angle ω.

Fig. 22 illustrates a distal end of a differential dissector 2210, the differential dissector 2210 including one embodiment of a reciprocating mechanism, referred to herein as a scotch yoke. The distal end of differential dissector 2210 includes a housing 2212, which further includes a pivot bearing 2214, a motor shaft bearing 2216, and a shaft drum bearing 2218. Fig. 22 also shows a motor shaft 2220, a shaft drum 2222 coaxial with the motor shaft 2220 and fixed to the motor shaft 2220, and a driver pin 2224, which may be parallel to the motor shaft 2220 but not coaxial with the motor shaft 2220, which driver pin 2224 is itself fixed to the shaft drum 2222. Further, the differential dissecting member DDM2230 is present in relation to the differential dissector housing 2212 and further includes a body defining the DDM2230, a tissue-engaging surface 2232 forming at least a portion of the outer surface 2231, a DDM pivot 2234 that fits into the pivot bearing 2214, and further includes a hollow DDM pin follower 2236 that effectively grasps the driver pin 2224. The internal three-dimensional shape of the hollow DDM pin follower 2236 shown herein is prismatic, such that in the view shown in fig. 22 the cross-sectional shape resembles an hourglass, however perpendicular to this view the cross-sectional shape is a straight line.

Fig. 23A, 23B, and 23C show cross-sectional views of a portion of the DDM2230 of fig. 22 through the narrowest part of the waist of the hourglass-shaped hollow DDM pin follower 2236, perpendicular to the axis of rotation of the shaft drum 2222. In this view, the DDM pin follower 2236 is rectangular in shape; further, in this view showing dimensions, the height of the rectangle through the waist of 2236 is equal to or greater than the diameter described by the outer diameter of driver pin 2224 along the circular path 2237 of driver pin 2224. In this view, the width of the rectangle corresponds to the outer diameter of the driver pin 2224. The DDM2230, including the hollow DDM pin follower 2236, rotates about an axis 2233 of the shaft 2234. Thus, the position of the hollow DDM pin follower 2236 and the rotational position of the DDM2230 are determined by the rotational position of the driver pin 2224.

In operation, referring to fig. 22, and following fig. 23A-23C, a motor (not shown) rotates motor shaft 2220, which rotates drum 2222 about its axis of rotation, causing driver pin 2224 to travel about a circular path 2237, the plane of which path 2237 is perpendicular to the axis of rotation of drum 2222. As in the scotch yoke, the rectangular hollow DDM pin follower 2236 translates the rotational path 2237 of the driver pin 2224 into a linear travel 2238 of the hollow DDM pin follower 2236; assuming that the pin follower 2236 is positioned a certain distance away from the axis 2233, the DDM2230 leverages about the axis 2233 to translate the rotational path 2237 into a linear travel 2238 and to reciprocate the DDM2230 that rotates about the DDM pivot 2234 held by the pivot bearing 2214. The pattern of reciprocation of the DDM2230 is controlled by varying the shape of the hollow DDM pin follower 2236, the 3D angle of the driver pin 2224, the axis 2233 about which the shaft 2234 rotates, the distance of the driver pin 2224 from the axis 2233, and also by varying the speed of rotation of the motor.

As shown in the side views of fig. 24A and 24B, the DDM2230 of fig. 22 can have reciprocating motions 2250 and 2251. The illustrated oscillation sequence depicts the extreme position of the DDM2230 as the driver pin 2224 travels around the circular path 2237 when provided with rotational motion 2299 from a motor (not shown). The action of the tissue engaging surface 2232 of the DDM2230 applied on the surface of the tissue to be dissected is best shown in the side view in fig. 20.

Surgeons operating on the interior of a patient wish to minimize trauma to tissue that is not the focus of the procedure, or is simply on the way through the target tissue. To this end, fig. 25A-25C depict an outline view of an embodiment of a mostly covered DDM assembly 2500, the DDM assembly 2500 further comprising a covered pivot 2510 projected perpendicularly to the page (i.e., at the viewer), an internal motor shaft 2550, an internal driver drum 2522, a driver pin 2524, a DDI housing 2512, a DDM2520 that reciprocates about the covered pivot 2510 (and in the plane of the page), a tissue-engaging DDM surface 2534, a smooth DDM surface 2518, a generally circular DDM region 2516, a shield edge 2517, and a shield-DDM gap 2514. All of the outer surfaces of the DDM assembly 2500 considered as a whole are considered to be integral, and the covered DDM assembly 2500 exhibits an almost continuously smooth surface of the patient's tissue. In this regard, except to a limited extent where tissue engages the DDM surface 2534, the entire differential dissecting instrument fitted with the DDM assembly 2500 does not behave much like a polished probe.

Once activated, DDM2520 reciprocates within housing 2512 and relative to housing 2512. At the edge of housing 2512 closest to DDM2520 is shield edge 2517. A shroud-DDM gap 2514 exists between the shroud edge 2517 and the DDM 2520. In one embodiment, a differential dissecting instrument adapted to the DDM assembly 2500 includes provisions for providing protection for the outwardly slippery nature of the differential dissecting instrument. Thus, the shield-DDM gap 2514 presents a challenge because any relative movement of the DDM2520 with respect to the housing 2512 can enlarge the shield-DDM gap 2514, presenting a sharp edge to the tissue. Alternatively, a portion of DDM2520 may impact housing 2512. Also, in one embodiment, the shroud-DDM gap 2514 is kept as small as possible at all times. To facilitate this, the DDM2520 has a circular DDM region 2516 defined as part of most DDMs 2520 in this perspective view, the DDM2520 having a cross-section in the form of a circle, the center of the circle coinciding with the axis of the overlying pivot axis 2510. This circular DDM region 2516 defines and occupies that portion of the outer surface of the DDM2520 that passes by the shield edge 2517 during reciprocation of the DDM2520, and is at a distance that defines a shield-DDM gap 2514. Because the circular DDM region 2516 maintains the same radius of the DDM2520 over the rotation angle, this keeps the shield-DDM gap 2514 at a constant value (i.e., the shield-DDM gap 2514 does not change even if the DDM2520 is moved). Thus, the differential dissecting instrument fitted with the DDM assembly consistently presents a continuous smooth surface throughout the tissue.

Fig. 25D depicts an oblique view of a majority of the covered DDM assembly 2500, showing the housing 2512, a DDM2520 (see fig. 25A-25C) reciprocating about the covered pivot axis 2510, a tissue engaging DDM surface 2534, a smooth DDM surface 2518, a generally circular DDM region 2516, a shield edge 2517, and a shield-DDM gap 2514.

When the target tissue is exposed, sharp dissection is usually performed alternating with blunt dissection. This occurs whenever a membrane or large fibrous component that resists blunt dissection encounters and must be severed, the surgeon penetrates further into the tissue. Current practice requires surgeons to use sub-optimal instruments (e.g., a less common electrotome) for blunt dissection or to exchange instruments when exposing the target tissue. Using a suboptimal instrument reduces the ease of blunt dissection and increases the potential risk of target tissue. Exchanging instruments is time consuming and distracting, especially for many minimally invasive procedures, the instruments must be passed through a slit in the body wall and then gently guided to the intended location, such as during laparoscopy and thoracoscopy. The differential dissecting instrument may be equipped with sharp dissecting members that can be selectively activated by the surgeon, eliminating the need for instrument exchanges while providing the surgeon with an optimal instrument.

FIG. 26A illustrates top and side views of an embodiment of a differential dissecting instrument 2600 similar to differential dissecting instrument 2000 illustrated in FIG. 20, but now further comprising a retractable dissecting blade that is covered during blunt dissection. The retractable scalpel blade can be projected outward by the surgeon for sharp dissection and then retracted before further blunt dissection is performed. The differential dissecting instrument 2600 has an elongated member comprised of a shield 2620, the DDM 2610 being rotationally mounted to the shield 2620 via a rotational shaft 2635. On one side of the DDM 2610 is a slot 2612 under which the retractable scalpel blade 2622 is positioned so that the retractable scalpel blade 2622 is completely covered by the shield 2620. Retractable dissection blade 2622 is actuated by a retraction mechanism (not shown) controlled by the surgeon. Actuating the retractable dissection blade 2622 may be manual via a slider, controlled by electrical actuation (such as a solenoid), or by any suitable mechanism controlled by an operator.

Fig. 26B shows the differential dissecting instrument 2600 with the retractable dissecting blade 2622 extended for sharp dissection. Retractable dissection blade 2622 is an example of a sharp dissection tool. In other embodiments, differential dissecting instrument 2600 may include other sharp dissecting tools such as an electric knife blade, an ultrasonic knife, or a breaking hook. In other embodiments, differential dissecting instrument 2600 may include a tool for high-energy disruption, such as an electrocautery blade or an electrocautery bit. Further, instead of being retracted, the retractable dissection blades 2622 or other suitable tools may be selectively exposed for use by one of several mechanisms, such as by pop-up, by extension, or other mechanisms known in the art.

FIG. 27 illustrates top and side views of another embodiment of a differential dissecting instrument 2700 similar to differential dissecting instrument 2600 shown in FIGS. 26A and 26B, but now harnessing grip member 2710 so that differential dissecting instrument 2700 also functions as a surgical clamp. The differential dissecting instrument 2700 has a DDM2710 rotatably attached to an instrument shaft 2720 and is rotated by a motorized mechanism (not shown). The push rod 2730 is inside the instrument shaft 2720 and is activated by a mechanism present in the handle (not shown) and manually by the operator. When DDM2710 is enabled, it oscillates back and forth as indicated by arrow 2740. When the operator cuts the action of the DDM2710, the operator can use the push rod 2370 to advance the surgical jaws 2750, which surgical jaws 2750 have control stubs 2760 that rotate the surgical jaws 2750 about the pivot point 2770 and thus open. The opposing jaw of the forceps is DDM 2710. The operator can grasp and release the object between the surgical jaws 2750 and the DDM2710 by pushing or pulling the push bar 2730.

Fig. 28 and fig. 29A to 29D depict another embodiment of a DDM. In fact, this embodiment has provided a very differential motion and rapid dissection through complex tissues. For this embodiment of the DDM, the protrusions of the tissue engaging surface are formed by valleys cut into the surface of the DDM. Referring to fig. 28, the DDM2800 has a first end 2810 and a second end 2820 with a central axis 2825 connecting the first end 2810 and the second end 2820. The first end 2810 is oriented away from the compound tissue (not shown) to be dissected and engages a drive mechanism (not shown) that moves the DDM2800, causing the second end 2820 to sweep in the direction of motion. Herein, the mechanism oscillates the DDM2800 about an axis of rotation 2830 that is perpendicular to the central axis 2825, such that the direction of motion 2840 is the arc of motion that exists in a plane that is perpendicular to the axis of rotation 2830. The second end 2820 has a tissue-facing surface 2850 directed toward the composite tissue that includes at least one tissue-engaging surface 2860 and at least one side surface 2870.

In this example, the motion of the DDM2800 is a reciprocating (back and forth) oscillation, but other DDMs can be continuously rotating or linear. Preferably, the rotation is between 2,000 and 25,000 cycles per minute, but may range from 60 to 900,000 cycles per minute, all at a lower speed than ultrasound. In certain embodiments, rates of 300 to 25,000 weeks per minute have been found to be significant.

Fig. 29A-29E show enlarged views of the tissue-facing surface 2850 of the DDM2800 of fig. 28. Fig. 29A shows an oblique view of the tissue-facing surface 2850 with the identified features. Fig. 29B-29D show a tissue-facing surface 2850 having a geometry of a better described shape, particularly different views of the component relative to the tissue-facing surface 2850. Finally, fig. 29E shows a different embodiment of some of these components. The tissue-facing surface 2850 has a tissue-engaging surface 2860 and two side surfaces, a first side surface 2871 disposed transversely relative to one side of the tissue-engaging surface 2860 and a second side surface 2872 disposed transversely relative to an opposite side of the tissue-engaging surface. Referring to fig. 29A and 29C, the tissue engaging surface 2860 is comprised of a series of at least one valley 2910 and at least one protrusion 2920 staggered along a direction of motion 2840 that is an arcuate motion on the tissue facing surface 2850 such that the intersection of the at least one valley 2910 and the at least one protrusion 2920 defines at least one valley edge 2930 oriented such that it has a directional component (component of direction) perpendicular to the direction of motion 2840.

The valley edges 2930 should not be sharp, e.g., the valley edges cannot cut into the composite tissue, especially hard tissue. For example, no point on the valley 2930 should have a radius of curvature R of less than about 0.025 millimeters_c(see FIG. 29C, enlarged view). The radius of curvature R_cRadius of curvature R of a surface similar to that described in FIG. 15_sRadius of curvature R of the side_e. We have shown by testing that the material has a radius of curvature R of no less than about 0.050 mm_cThe edges of (2) also have an effect. Further, the radius of curvature R_cCan vary with the length of the valley 2930. In the embodiment shown in fig. 29A to 29D, the radius of curvature R_cIs smallest at the location where valley 2930 is farthest from axis of rotation 2830 and increases as it approaches first side surface 2871 and second side surface 2872. Furthermore, in the same DDM, the smallest radius of curvature R of the valley 2930_cIs different for different valleys, even for valleys on opposite sides of the same valley.

In one embodiment, the protrusions 2920 of the DDM2800 can be produced by deletion. Indeed, as shown in fig. 29B-29C, the valley 2910 is a semi-ellipsoid cut out on the surface, with a rotation speed 2830 aligned vertically and a semi-major axis a (i.e., pointing towards complex tissue) parallel to the central axis 2825 (see fig. 28), a first semi-minor axis B, and a second semi-minor axis C parallel to the rotation speed 2830. Thus, the projection 2920 has a semi-elliptical surface left and a projection top 2940 connected to the side surfaces 2971 and 2972. Thus, in this embodiment, the tissue-engaging surface 2860 is created by the side limitations of the valleys 2910 and spans the tissue-facing surface between the valleys 2910 forming the projections 2920. In other embodiments, the protrusions can be formed in other ways, and thus have more differently shaped protrusion tops, including not forming the protrusion tops as the remainder of the surface. For example, in one embodiment, the protrusions can effectively be set up from the surface, thereby creating more complex protrusion tops.

Referring to fig. 29A and 29C, each valley 2910 may have a first valley side (valley side) 2911, a second valley side 2912, and a valley bottom 2913, whereby the first and second valley sides 2911 and 2912 are located at opposite sides of the valley 2910. The valley 2913 is linear or curvilinear and two-dimensional or three-dimensional. For example, the valley bottom of the DDM2800 is a straight line aligned and parallel to the rotation speed 2830. The first and second valley sides 2911 and 2912 rise from the valley bottom 2913 to a valley edge 2930. The transition from the valley bottom is slow and uncertain, like the valley 2910 in the DDM2800, or the transition may be faceted. The valley 2910 may be curved in two dimensions, being straight in a direction parallel to the valley 2913 (and thus also parallel to the axis of rotation 2830). However, the valley sides may be any shape, including curved surfaces in three dimensions.

The valley is formed by the intersection of a valley slope (valley wall) with the top of the protrusion. Thus, the valley edges have different shapes depending on the shape of the protrusion top and the valley edges. The valley edges 2930 on the DDM2800 follow a three-dimensional curve and thus have a non-zero degree of curvature and twist (defined mathematically in geometry) and vary along the valley edges. The valleys have smoothly varying curvatures and twists (as with valley 2930) or the valleys can be bent.

Fig. 29C shows an enlarged view of the valley edge in a plane perpendicular to the valley edge. The protrusion top 2920 and the valley side (here 2911 or 2912) form a face angle (face angle) Γ in this plane that is rounded (i.e., it is "rounded" as described by mechanics) at the intersection, the intersection having the radius of curvature R described above_c. The face angle Γ can form an angle of less than 90 degrees, which is acute when first tested, but the sharpness is determined by the radius of curvature R of the edge_cAnd (4) determining. The face angle Γ may vary along the length of the valley edge,as it is for the DDM2800, the face angle Γ is smallest at the point on the valley edge furthest from the axis of rotation 2830. In one embodiment, about thirty degrees (30)^o) Face angles of up to about one hundred fifty degrees (150 °) are effective.

The valleys have a length, a width, and a depth, where the valley length is the valley bottom length, the valley width is the distance separating the valley edges of one valley measured at their longest separation distance, and the valley depth is the maximum vertical distance from the valley edge to the valley bottom (i.e., the peak to valley height). Typical dimensions of the valleys include a valley length of 0.25 mm to 10 mm, a valley width of 0.1 mm to 10 mm, and a valley depth of 0.1 mm to 10 mm. In one embodiment, a valley length of about three (3) millimeters, a valley depth of about three (3) millimeters, and a valley width of about two (2) millimeters have been found to be particularly effective.

When the DDM has multiple valleys, like the DDM2800, the valleys can be arranged in parallel, like the valleys 2910 of the DDM2800, with all parallel valleys 2913, or they are not parallel to the valleys, arranged at a non-zero angle with respect to each other, or arranged at a variable angle with respect to each other.

The valley 2910 of the DDM2800 has individual channels (space is bounded by valley sides and valley bottom); however, the valleys have a plurality of intersecting channels, thereby allowing the valley floor to diverge or branch off into multiple branches or form a network on the tissue engaging surface. Figure 29E shows a top view of two DDMs, the left DDM 2980 with a valley 2981 parallel to the valley floor is not parallel to the rotation speed, while the right DDM 2990 has a network 2991 of multiple intersecting valleys at different angles relative to the rotation speed and relative to each other.

As described above, the tissue-facing surface 2850 of the DDM2800 has a semi-ellipsoidal surface with a semi-major axis a, a first semi-minor axis B, and a second semi-minor axis C parallel to the rotational axis 2830 aligned perpendicular to the rotational axis 2830 and parallel to the central axis 2825. In one embodiment, the tissue facing surface 2850 can have an ellipsoidal shape, where A > B > C. However, any relationship between the lengths of the axle half shafts is possible. For example, in one embodiment, DDM may be manufactured with a = B = C (e.g., the tissue facing surface is hemispherical).

The first side surface 2871 and the second side surface 2872 of the DDM2800 are extensions of a semi-elliptical shape. Likewise, they are placed at an angle to each other to form a wedge, as described earlier in fig. 19D and 20, to align and stretch the fibrous components of the composite tissue, causing the protrusions to puncture and disrupt the fibrous components.

Fig. 30 shows a first tissue region 3011 enclosed in a first membrane 3016 and a second tissue region 3012 enclosed in a second membrane 3017. The first and second membranes 3016 and 3017 abut the tissue plane 3020. First and second membranes 3016 and 3017 are made up of tightly packed fibrous components and therefore include hard tissue. The interstitial material spanning the tissue plane from the first membrane 3016 to the second membrane 3017 includes fibrous components 3030. Because these fibrous components 3030 are not tightly packed, the interstitial material includes soft tissue. When tissue-facing surface 2850 is pressed into tissue plane 3020 in the direction of arrow 3050 to separate two tissue regions 3011 and 3012, first side surface 2871 and second side surface 2872 apply first expansion force 3041 and second expansion force 3042, respectively, to tissue regions 3011 and 3012, aligning and stretching fibrous element 3030 at protrusion top 2940 (see fig. 29C). This causes the fibrous component 3030 to enter the valley 2910 and thus be punctured and torn by the projection 2920, moving out of the plane of the page (toward the viewer) as the tissue-facing surface 2850 rotates about the axis of rotation 2830. In addition, as projection tops 2940 continue with the sides, more of the side areas of projection tops 2940 also exert additional expansive forces 3043 and 3044 that wedge tissue regions 3011 and 3012 apart, further enhancing the strain on fibrous component 3030.

Figure 30 also illustrates important aspects of DDM. The DDM will automatically follow the tissue plane. Because tissue planes tend to be bounded by hard tissue (e.g., membranes, conduits, etc.), and are spanned by soft tissue, the DDM will by virtue of its differential action not move into hard tissue and will enter soft tissue, so following and separating tissue planes can only obtain little or no guidance from the operator. This means that the operator does not need a detailed understanding of the anatomy as required by existing methods, or, conversely, DDM makes the surgeons more confident about anatomically indeterminate anatomy, for example, when tissue planes are distorted by tumors or when tissue is in a swollen or inflamed state).

Fig. 31 shows an end view of the tissue-facing surface 2850 rupturing and extending to destroy the fibrous component 3030 shown in fig. 30. Three fibrous components (first fibrous component 3031, second fibrous component 3032, and third fibrous component 3033) have been punctured by three protrusions (first protrusion 2921, second protrusion 2922, and third protrusion 2923, respectively). The tissue facing surface 2850 rotates generating a direction of motion 2840 that is an arc of motion depicted by arrow 3100. The first fibrous component 3031 has just entered the first valley 2911 and has not yet been punctured by the first projection 2921. The second fibrous component 3032 enters the second valley 2912 at an earlier location in time and has been punctured and strained by the second projection 2922. The third fibrous component 3033 enters the third valley 2913 at an earlier location in time and has been further torn and strained by the third projection 2923. Finally, all the fiber components 3031, 3032, and 3033 are pulled to break.

Figure 31 illustrates important aspects of the design of the DDM 2800. Because the valleys span from one side surface 2871 to the opposite side surface 2872, each valley creates an open space across the end of the DDM2800, the tensioned fiber components can enter the end of the DDM2800, thus facilitating their puncture by the protrusions.

It is important to note that the DDM2800 does not have an array of small protrusions giving any part of its surface texture as described earlier. In contrast, all surfaces of the DDM2800 are smooth, preferably possessing a low friction surface. The shape and structure of the surface features of the DDM2800 are responsible for its ability to dissect complex tissues differentially. In fact, the DDM2800 works best when all DDM surfaces in contact with tissue are lubricated using, for example, surgical lubricating oil.

FIG. 32 illustrates an exploded view of one embodiment of a complete differential dissecting instrument. Differential dissecting instrument 3200 is entirely comprised of instrument handles 3212 with an instrument insertion tube 3290 protruding from instrument handles 3212, instrument insertion tube 3290 having a first end 3291 attached to instrument handles 3212 and a second end 3292 with a DDM3292 rotatably mounted. The instrument handle 3212 is assembled from an upper housing 3220 and a lower housing 3230, the upper housing 3220 including an upper battery cover 3222, the upper housing 3220 and the lower housing 3230 held together by an instrument housing bolt 3236. Included in the upper and lower housings 3220 and 3230 are a motor 3260 and a battery pack 3270. Within the upper housing 3220 is a switch port 3224 through which a switch 3282 (which may be a momentary switch or an on-off switch) may be passed to provide power from the battery pack 3270 to the motor 3260. A printed circuit board 3280 is provided that further contains a power level adjuster 3281 (which may be any convenient component, but is shown here as a linear potentiometer), and the printed circuit board 3280 is accessed through a flexible switch cover 3284 mounted in the surface of the upper housing 3220. Also included are forward and rearward spring battery connectors 3272, 3274 that carry power from the battery pack 3270. The upper housing 3220 further includes an instrument insertion tube support 3226 to secure and orient the instrument insertion tube 3290 proximate to and coaxial with the motor 3260.

The lower housing 3230 is further retained to the upper housing 3220 using an integral lower battery cover 3232 and motor housing portion 3234 to access and protect the battery pack 3270, and further using three instrument housing bolts 3236. The motor housing portion 3234 holds and secures a motor 3260 coaxial with an instrument insertion tube 3290, which instrument insertion tube 3290 passes through the instrument insertion tube support 3226. The motor 3260 is pressed forward against the motor collar 3264 by the motor housing portion 3234, and the inner diameter of the motor collar 3264 allows space for the motor coupling 3262. Motor coupling 3262 is securely mounted to one end of the shaft of motor 3260 with the aid of motor coupling bolt 3266 and further clamps against first end 3295 of drive shaft 3294. The drive shaft 3294 is rotated by a motor 3260 inside the instrument insertion tube 3290 and concentric with the instrument insertion tube 3290. The drive shaft 3294 also has a second end 3297 of the drive shaft 3294 that is concentrically supported by a bearing 3296 mounted on the second end 3293 of the instrument insertion tube 3290. The DDM3292 is rotatably mounted on bearings 3296 such that the drive shaft 3294 rotates the DDM 3292. The DDM3292, bearings 3296, drive shaft 3294, and instrument insertion tube 3290 collectively form a DDM assembly 3299, described below.

Fig. 33A, 33B, and 33C depict details of a DDM assembly 3299, including: how to assemble the DDM assembly 3292 with other components so that the motor 3260 drives the DDM3292 to oscillate.

Referring now to fig. 33A, in this embodiment, a DDM3292 includes a tissue-facing surface 3322 on a first end 3321 and a bearing grip 3324 on a second end 3323. Bearing grip 3324 further cooperates with two pivot pins 3325. DDM3392 may be partially hollow, possessing a bearing cavity 3326 that allows bearing 3296 to fit inside. Bearing cavity 3326 further supports cam follower cavity 3328. The shape of the cam follower cavity 3328 may be an oval that is narrower in one direction, forming a slot. Bearing 3296 has a bore 3336, a bearing tip 3332, a threaded bearing end 3338, and two pivot pin holes 3334. The threaded bearing end 3338 is threaded into a threaded bearing mount 3342 at the second end 3293 of the instrument insertion tube 3290. The diameter of the bore 3336 may be larger than the diameter 3385 of the drive shaft 3294 at any location along its length except for the bearing tip 3332, thereby reducing the contact surface between the bearing 3296 and the drive shaft 3294. The second end 3297 of the drive shaft 3294 is modified to include a main shaft portion 3352 and a cam shaft portion 3354. The various subcomponents of these components enable their assembly and operation, as seen in fig. 33B and 33C.

Referring now to fig. 33B, there is shown a drive shaft 3294 coaxially fitted within a bearing 3296 of a DDM assembly 3299 and an instrument insertion tube 3290. This aligns the threaded bearing end 3338 of the bearing 3296 for threading into the threaded bearing mount 3342 positioned at the second end 3293 of the instrument insertion tube 3290. The bearing tip 3332 houses the drive shaft 3294 and prevents misalignment with respect to the DDM 3292. A second end 3293 of the drive shaft 3294 emanates from the bearing tip 3332, leaving the cam shaft portion 3354 fully exposed. Once the instrument insertion tube 3290, bearing 3296 and drive shaft 3294 are assembled, the DDM3292 is mounted on the bearing 3296 such that (a) the pivot point pin 3325 is inserted into the pivot pin hole 3334 and (b) the cam shaft portion 3354 is inserted into the cam follower cavity 3328, as shown in fig. 33C.

Fig. 33C depicts an assembled DDM assembly 3299. The DDM3292 fits over a bearing 3296, the bearing 3296 screws into a threaded bearing mount 3342 of the instrument insertion tube 3290, all of which coaxially include a drive shaft 3294. Note that pivot pin 3325 on bearing grip 3324 fits into pivot pin bore 3334 of bearing 3296. This arrangement in combination with bearing cavity 3326 allows the hollow DDM3392 to rotate freely on pivot pin 3325. Rotation of the drive shaft 3294 rotates the cam shaft portion 3354 within the cam follower cavity 3328, thereby driving the DDM3392 to oscillate about the pivot pin bore 3334 and sweep the tissue-facing surface 3322 side-by-side as indicated by the double-headed arrow 3377.

Referring to fig. 32 and 33A-33C, in operation, the surgeon holds differential dissecting instrument 3210 by instrument handle 3212 and orients the distal tip of the supporting DDM3292 toward the complex tissue to be dissected. The surgeon selects the power level by sliding the power level adjuster 3281 to the desired position, then places his thumb on the switch 3282 and presses the thumb to close the switch. When the switch 3282 is closed, the motor 3260 turns on and rotates the motor coupling 3262, which in turn rotates the drive shaft 3294. The drive shaft 3294 is held coaxially and at a very precise position by a bearing 3296, and in particular by a bearing tip 3332, such that the camshaft portion 3354 of the drive shaft 3294 oscillates rotationally inside the cam follower cavity 3328 of the bearing cavity 3326 of the DDM 3292. The cam follower cavity 3328 is oval shaped and in the embodiment shown in fig. 33A-33C, the cam follower cavity 3328 has its narrowest dimension in a direction perpendicular to the axis of the rotational joint formed by the pivot pin 3325 and the pivot pin hole 3334. In this embodiment, the narrowest dimension of the cam follower cavity 3328 allows passage only through the cam shaft portion 3354 of the rotating drive shaft 3294. Thus, the rotational oscillation of the cam shaft portion 3354 strikes the long wall of the cam follower cavity 3328, forcing the entire DDM3292 to rotate through an oscillation arc 3377 lying in a plane perpendicular to the axis of the rotational joint formed by the pivot pin 3325 and pivot pin hole 3334. In this embodiment, the amplitude of the oscillation arc 3377 of the oscillation of the tissue-facing surface 3322 of the differential dissecting member 3292 is a function of the diameter 3385 of the drive shaft 3294 that cuts the camshaft portion 3354 and the distance 3379 separating the tissue-facing surface 3322 from the pivot pin bore 3334. The oscillation frequency matches the oscillation frequency of the rotation of motor 3260. The operator can control the frequency of oscillation of the tissue-facing surface 3322 by changing the position of the power level adjuster 3281. Note that this mechanism that converts rotation of the motor 3260 and rotation of the drive shaft 3294 into oscillation of the DDM3292 is similar to the scotch yoke depicted in fig. 22-25C.

The differential dissecting instrument 3200 is one example of a DDM embodiment, and many variations are possible. For example, the oscillation of the DDM may be driven by a crank-slider mechanism having a slider that moves back and forth longitudinally inside the instrument insertion tube. Alternatively, a motor may be provided adjacent the DDM, with a motor shaft that directly drives the DDM and only provides power from the electrical wires to the motor that stops the operation of the instrument insertion tube. Furthermore, because the DDM is well-adapted to the end of the tube, greatly extending the instrument insertion tube allows for differential dissecting instruments, such as differential dissecting instrument 3200, to be laparoscopic instruments, for example. Differential dissecting instruments with instrument insertion tubes may be thirty-six (36) centimeters long, but longer or shorter tubes are readily available in the design. The DDM disclosed herein can be easily adapted to the robotic arm of a Surgical Robot, such as Da Vinci Surgical Robot from Intuitive Surgical (Sunnyvale, california). The DDM can be made very small; for example, a fitting constructed in an effective differential dissecting instrument can be passed through a five (5) millimeter hole, such as the DDM of a surgical port and an instrument insertion tube, to complete a minimally invasive surgical procedure. These smaller devices can be easily manufactured.

Further, the differential dissecting instrument may be used in a drive shaft that is replaced with a flexible drive shaft, and the instrument insertion tube is curved. This produces a differential dissecting instrument with a curved instrument insertion tube, as shown in FIG. 6C. Articulation of the instrument insertion tube is also possible, for example, using a drive shaft with a universal joint or other flexible coupling at the articulation.

As previously disclosed, additional functionality may be added to the ends of the differential dissecting instrument. For example,

fig. 11B and 13 show how the design of the DDM allows fluid to be delivered to the DDM for irrigation, or how suction is applied to clear the surgical field, or how a light source is placed on or near the DDM to illuminate the surgical field.

Figures 26A and 26B disclose that the cutting blade with telescoping can be made sharp to cut or be energized by an electrosurgical generator (monopolar or bipolar) for electrosurgery,

figure 27 shows how the design of the DDM allows the DDM to be adapted for use as a surgical clamp.

Additional functions can be easily added to the differential dissecting instrument. For example, any size piece on one side of the DDM or a shield supporting the DDM can be energized and thus can be used for electrocautery. To simplify manufacturing, a drive shaft can be used to conduct electricity from the handle to the DDM. The design of the DDM allows the surgical forceps shown in fig. 27 to be substituted for scissors. The improved design of the DDM allows these additional functions to be combined together in a differential dissecting instrument. Advantages of combining DDM with these functional implementations at the working end of a differential dissecting instrument include: reduces the number of instruments required by the surgeon during surgery; simplifies the inventory of logistics personnel for hospitals and logistics; and most importantly, reduces instrument changes during surgery that slow down the surgical procedure and cause a major source of surgical complications. This is especially true in laparoscopic and robotic procedures where instruments need to be positioned within the human body through small incisions, often using airtight ports.

FIG. 34 illustrates an oblique view of one embodiment of an assembled differential dissecting instrument. Differential dissecting instrument 3400 is entirely comprised of instrument handle 3412, instrument insertion tube 3490 protrudes from instrument handle 3412, and instrument insertion tube 3490 has a first end 3491 attached to instrument handle 3412 and a second end 3493 rotatably mounting DDM 3492. Instrument handle 3412 is assembled from an upper housing 3420 and a lower housing 3430, with upper housing 3420 including an upper battery cover 3422 and lower housing 3430 including a lower battery cover 3432. Enclosed in the upper and lower cases 3420 and 3430 are a motor 3640 and a battery 3470, and the battery 3470 may be optionally assembled into a battery pack. Within the upper housing 3420 is a switch 3482 (which may be a momentary switch or an on-off switch) that can provide power from the battery pack 3470 to the motor 3460. A flexible switch cover 3484 mounted in the surface of the upper housing 3420 allows access to the interior of the power level adjuster 3581 (fig. 35A). Upper housing 3420 further includes a retractable blade hook control button 3499 (secured by control button bolt 3498), and an instrument insertion tube support 3426 for orienting an instrument insertion tube 3490 adjacent to and coaxial with motor 3460.

FIG. 35A shows an exploded view of differential dissecting instrument 3400. Differential dissecting instrument 3400 is entirely comprised of instrument handle 3412, instrument insertion tube 3490 protrudes from instrument handle 3412, and instrument insertion tube 3490 has a first end 3491 attached to instrument handle 3412 and a second end 3493 rotatably mounting DDM 3492. Instrument handle 3412 is assembled from an upper housing 3420 and a lower housing 3430, with upper housing 3420 including an upper battery cover 3422, lower housing 3430 including a lower battery cover 3432, and upper housing 3420 and lower housing 3430 held together by instrument housing bolts 3536. Included within the upper housing 3420 and lower housing 3430 are a motor 3460 and a battery 3470, shown herein as battery type CR123A (3V for each battery and 18V for all 6 batteries 3470), although other battery types and voltages may be used. In certain embodiments, batteries having a total voltage as low as 3V have been used. Within the upper housing 3420 is a switch port 3524, and a switch 3482 (which may be a momentary switch or an on-off switch) is accessible through the switch port 3524 to provide power from the battery pack 3470 to the motor 3460. A printed circuit board 3580 is provided that further contains a power level adjuster 3581 (which may be any convenient component, but is shown herein as a linear potentiometer), and the printed circuit board 3580 is accessible through a flexible switch cover 3484 mounted to a surface of the upper housing 3420. A forward spring battery connector 3572 and a rearward spring battery connector 3574 are also included, the forward spring battery connector 3572 and the rearward spring battery connector 3574 carrying power from the battery 3470. Upper housing 3420 further includes an instrument insertion tube support 3426 to secure and orient instrument insertion tube 3490 proximate to and coaxial with motor 3460. Instrument insertion tube retaining bolt 3527 fixedly retains instrument insertion tube 3490 in instrument insertion tube support 3426.

The lower housing 3430 further provides access to the battery 3470 and secures the battery 3470 with the complete lower battery cap 3432 and motor housing portion 3534, further using the three instrument housing bolts 3536 to hold the complete lower battery cap 3432 and motor housing portion 3534 to the upper housing 3420. The motor housing portion 3534 holds and fixes the motor 3460 coaxially with an instrument insertion tube 3490, which instrument insertion tube 3490 passes through the instrument insertion tube support 3426. The motor housing portion 3534 presses the motor 3460 forward against the motor spring 3562, which motor spring 3562 has an inside diameter that leaves room for the motor coupling 3562. Under the action of the motor coupling bolt 3566, the motor coupling 3562 is fixedly mounted to the end of the shaft of the motor 3460 and further grasps the first end 3595 of the drive shaft 3494. Motor 3460 can slide longitudinally back and forth within motor housing portion 3534 under the control of retractable blade hook control button 3499. The motor 3460 further includes a power contact plate 3569 that is operable to slide against spring motor power contacts 3563 mounted on a circuit board 3580. Also mounted on circuit board 3580 is adjustable power contact pressure control bolt 3561. Normally, the spring 3567 keeps the motor 3460 rearward. In this position, spring motor power contacts 3563 mounted on printed circuit board 3580 are aligned with and pressed against power contact plate 3569 on motor 3460 so that power from battery pack 3470 can drive the motor to rotate. Pressing the retractable blade hook control button 3499 forward slides the motor 3460 forward. Power contact plate 3569 is shorter than the full travel of motor 3460 under the influence of retractable blade hook control button 3499, thereby causing power from battery pack 3470 to automatically be cut off when motor 3460 slides forward toward insertion tube second end 3493 far enough to break contact with spring motor power contact 3563.

Drive shaft 3494 also has a second end 3597, which second end 3597 passes through and is concentrically supported by a bearing 3496 mounted to a second end of instrument insertion tube 3490. Still referring to fig. 35B, the second end 3597 of the drive shaft 3494 further includes (running inward from the tip of the second end 3597) a cam receiver retainer 3555, a cam receiver driver 3554, and a bearing clearance portion 3552. The DDM3492 is rotatably mounted on bearings 3496 such that the drive shaft 3494 rotates the DDM3492 with reciprocating oscillations. The DDM3492, bearings 3496, cam receiver 3596, cam receiver holder 3555, drive shaft 3494 and instrument insertion tube 3490 together form a DDM assembly 3598, which will be described next for DDM assembly 3598.

Fig. 35B depicts details of a DDM assembly 3598, including: how to assemble the DDM3492 with other components so that the motor 3460 drives the DDM3492 to oscillate back and forth. In this embodiment, the DDM3492 comprises a tissue-facing surface 3522 at a first end 3521 and a bearing grip 3524 at a second end 3543. Bearing grip 3524 further cooperates with two pivot pin holes 3525. The DDM3492 may be partially hollow, possessing a bearing cavity 3526 that allows the bearing 3496 to fit inside. The bearing cavity 3526 further supports a cam receiver cavity 3548 that is shaped to allow the cam receiver 3596 to slide easily therein. In this embodiment, the tissue-facing surface 3522 of the DDM3492 further includes a retractable blade slot 3506. The bearing 3496 has a bore 3536, a bearing tip 3532, a threaded bearing end 3538, and two insertable pivot pins 3535, the two pivot pins 3535 fitting into the threaded holes 3534. Threaded bearing end 3538 is threaded into a threaded bearing mount 3542 located on second end 3493 of instrument insertion tube 3490. The diameter of the bore 3536 may be larger than the diameter 3585 of the drive shaft 3494 at any location along its length except at the bearing tip 3532, thereby reducing the contact surface between the bearing 3496 and the drive shaft 3494. The second end 3497 of the drive shaft 3494 is modified to include a main shaft portion 3552, a cam shaft portion 3554 and a cam receiver retainer 3555. The cam receiver 3596 further includes a cam receiver body 3502, a cam receiver chamber 3505, and a retractable blade 3501. The retractable blade may further include hooks 3504 and a tissue engaging surface 3503. The various subcomponents of these components allow them to be assembled and operated as described elsewhere in this embodiment.

The DDM3492 fits over a bearing 3496, which bearing 3496 screws into a threaded bearing mount 3542 of an instrument insertion tube 3490, all of which coaxially include a drive shaft 3494. Note that pivot pin hole 3525 on bearing grip 3524 fits onto pivot pin 3535 of bearing 3496. This arrangement, in conjunction with the bearing cavity 3526, allows the DDM3492 to rotate freely on the pivot pin 3535. Rotation of the drive shaft 3494 rotates the cam shaft portion 3554 within the cam receiver 3596, thereby driving the DDM3492 to oscillate back and forth about the pivot pin bore 3525 and sweep the tissue-facing surface 3522 side-by-side.

In operation, a surgeon holds differential dissecting instrument 3400 by instrument handle 3412 and orients the distal tip supporting DDM3492 toward the complex tissue to be dissected. The surgeon selects the power level by sliding the power level adjuster 3581 to the desired setting, then places his thumb on the switch 3482 and presses the thumb to close the switch. When the switch 3482 is closed, the motor 3460 is turned on and causes the motor coupling to rotate, which in turn causes the drive shaft 3494 to rotate. The drive shaft 3494 is held coaxially and at a very precise position by the bearing 3496, and in particular by the bearing tip 3532, such that the cam shaft portion 3554 of the drive shaft 3494 rotationally oscillates within the cam receiver chamber 3505 of the cam receiver 3502 trapped within the DDM 3492. The rotational oscillation of the cam shaft portion 3554 strikes the walls of the cam receiver cavity 3505 of the cam receiver 3502 configured as a scotch yoke as previously described, forcing the entire DDM3492 to rotate in an arc of oscillation in a plane perpendicular to the axis of the rotational joint formed by the pivot pin 3535 and pivot pin hole 3525. The surgeon may extend the retractable blades 3501 by pushing the retractable blade hook control button 3499 forward. Forward movement of the retractable blade hook control knob 3499 moves the motor 3460 and power contact plate 3659 forward, thereby separating the power contact plate 3569 from the spring motor power contact 3563 and cutting off power to the motor as previously described and preventing the DDM3492 from oscillating. At the same time, forward movement of the motor 3460 pushes the drive shaft 3494 forward toward the second end 3493 of the instrument insertion tube 3490. The forward movement of the drive shaft 3494 in turn pushes the cam receiver retainer 3555 against the top of the cam receiver chamber 3505 inside the cam receiver body 3502, thereby pushing the cam receiver body 3502 further into the cam receiver cavity 3548 and extending the retractable blades 3501 out of the retractable blade slots 3506. Thus, forward movement of the retractable blade hook control button 3499 stops the motor 3460 and extends the retractable blade 3501 out of the DDM 3492. After releasing retractable blade hook control button 3499, motor spring 3562 pushes motor 3460 rearward, retracting retractable blade 3501 and restoring the electrical contacts for the motor.

In this embodiment, the amplitude of oscillation through which the tissue-facing surface 3522 of the differential dissecting member 3492 oscillates is a function of the diameter 3585 of the drive shaft 3494 cutting off the cam shaft portion 3554 and the distance 3579 separating the tissue-facing surface 3522 from the pivot pin hole 3525. The frequency of reciprocal oscillation (cycles per minute) of the DDM3492 against the complex compound tissue matches the rotational frequency (revolutions per minute) of the motor 3460. The operator can control the frequency of oscillation of the tissue-facing surface 3342 by changing the position of the power level adjuster 3581. Note that this mechanism that converts the rotation of the motor 3460 and the rotation of the drive shaft 3494 into the oscillation of the DDM3492 is similar to the scotch yoke depicted in fig. 22 to 25C.

Fig. 35C illustrates the forward/backward movement of the drive shaft 3494 and the cam receiver body 3502, also altering the reciprocating oscillation amplitude of the DDM 3492. The drive shaft 3494 is depicted in a rearward position (moving in the direction of arrow 3595) in the left frame and a forward position (moving in the direction of arrow 3597) in the right frame of fig. 35C. Thus, as the cam receiver body 3502 moves forward inside the cam receiver cavity 3548, the distance D from the cam receiver body 3548 to the pivot pin hole 3525 increases to D', while the lateral displacement of the receiver 3599 remains constant (as determined by the diameter 3585 of the drive shaft 3494, as described above). As D' increases, the larger angular amplitude of the DDM 3596 in the left frame decreases to the smaller angular amplitude of the DDM3598 in the right frame. This effect can be used to reduce the oscillation amplitude when the retractable blade is extended. This effect can also be used to alter the oscillation amplitude during blunt dissection by the DDM, for example, when the surgeon needs a narrower oscillation in order to perform more precise dissection.

Fig. 36A and 36B illustrate the end of a differential dissecting instrument 3600 having a DDM3610 rotatably mounted to an instrument insertion tube 3620 via a rotary joint 3630. The differential dissecting instrument 3600 also has retractable hooks 3640 that can be extended or retracted by moving in the direction indicated by double arrow 3650. Retractable hooks 3640 can be retracted or extended using a mechanism such as that described in fig. 34, 35A, and 35B. Fig. 36A illustrates how retractable hooks 3640 can be placed into two configurations. Configuration 1 shows retractable hook 3640 in an extended position, while configuration 2 shows retractable hook 3640 in a retracted position. The retractable hook 3640 may have: a tip 3670, which may be pointed or rounded; and, a tissue engaging surface 3660, which may be more aggressive or less aggressive than the tissue engaging surface 3690 of the DDM 3610. The retractable hook 3640 possesses an elbow 3680, which elbow 3680 may be sharp for slicing, as shown herein, or may be blunt; moreover, the elbow 3680 may be serrated, and the sharply treated region may be located anywhere within the elbow. In configuration 2, the retractable hooks are hidden inside the DDM3610, and the DDM3610 interacts with the tissue alone. In configuration 1, the retractable hook 3640 is exposed and available for interacting with tissue, either to cause the tissue engaging surface 3690 to interact with tissue (e.g., disrupt soft tissue), or to cause the tip 3670 to interact with tissue (e.g., pierce tissue), or to cause the elbow 3680 to interact with tissue (e.g., slice tissue), depending on how the operator positions the retractable hook 3640 relative to the tissue. Further, retractable hook 3640 may be held at any intermediate position between configurations 1 and 2, including being variably extendable by an operator.

Fig. 36B shows an end of a differential dissecting instrument 3600 illustrating that the DDM3610 may oscillate when the retractable hook is in the extended configuration (configuration 1) or the retracted configuration (configuration 2), and illustrating that the retractable hook 3640 may retract or extend before enabling oscillation of the DDM3610 or during oscillation of the DDM 3610. Arrow 3601 shows the retractable hook moving from a retracted configuration (lower left frame) to an extended configuration (upper left frame) when the DDM3610 is not oscillating. Arrow 3602 shows that the DDM3610 can be switched from stationary (top left box) to oscillating (top right box) when the retractable hook 3640 is in the extended configuration. Arrow 3603 shows that retractable hooks 3640 can move from an extended configuration (upper right frame) to a retracted configuration (lower left frame) as DDM3610 oscillates. Arrow 3604 shows that the DDM3610 can change from stationary (lower left frame) to oscillating (lower right frame) when the retractable hook 3640 is in the retracted configuration. Alternatively, the retractable hooks 3640 can be made of an electrically conductive material (e.g., stainless steel) and electrically connected to an external electrosurgical generator such that the retractable hooks 3640 act as electrosurgical hooks.

Many tissues that require dissection are enclosed by membranes or balloons, which the surgeon must separate to access. Once the membrane or pouch is separated, the surgeon dissects the tissue. Fig. 37 illustrates in four panels a method of safely and quickly separating membranes 3710 of overlapping tissues 3700 (such as the peritoneum of an overlapping gallbladder or the pouch surrounding the liver) using a differential dissecting instrument 3600. In the upper left panel, the differential dissecting instrument is seen approaching the membrane 3710, with the retractable hooks 3640 in the extended configuration. In the upper right panel, the tissue engaging surface 3660 of the retractable hooks 3640 is pressed against the membrane 3710 by the surgeon and the DDM3610 is oscillated causing the tissue engaging surface 3660 to abrade the membrane 3710. (alternatively, the retractable hooks 3640 may be held in the retracted configuration and the membrane 3710 may be abraded using the tissue-engaging surfaces 3690 of the DDM3610 if the two tissue-engaging surfaces 3660 and 3690 have different levels of attack, then the surgeon has the flexibility to choose a more aggressive or less aggressive tissue-engaging surface to abrade the membrane 3710.) the tissue is abraded until a small opening 3720 is formed in the membrane 3710. Next, as shown in the lower left panel, the surgeon pierces the sharp 3670 of the retractable hooks 3640 through the openings 3720 into the underside of the membrane 3710, causing the thin sheet 3730 of membrane 3710 to lift or "bunch" from the tissue 3700. The surgeon then moves the DDM 3600 in the direction of arrow 3740, forcing the sheet 3730 into the elbow 3680 of the retractable hook 3640, which elbow 3680 sharpens for sectioning tissue. Finally, as shown on the lower right panel, the surgeon oscillates the DDM3610 causing the retractable hook 3640 to oscillate, whereby the sharp edge of the elbow 3680 of the retractable hook 3640 moves rapidly into the film 3710 as the surgeon continues to move the DDM 3600 in the direction of arrow 3740. This has been demonstrated with fresh tissue in an easy, quick and safe way to separate membranes, such as the peritoneum that overlaps the gallbladder and biliary tract, without damaging underlying structures (e.g., gallbladder, biliary tract or liver). The tips 3680 of the retractable hooks 3640 may be blunt so as not to easily penetrate the film 3710 or underlying structure; moreover, placing a sharp edge only at elbow 3680 prevents critical structures from being exposed to sharp edge 3680, thereby reducing the likelihood of cutting such critical structures. Examples of membranes or balloons that overlap critical structures include: peritoneum that overlaps the liver, gallbladder, cystic duct, and cystic artery; and, pleura that overlaps lung, pulmonary artery, pulmonary vein, and bronchus.

The retractable hook may be used in a method similar to that shown in fig. 37 to dissect fibrous structures (e.g., adhesions, fibrous tissue surrounding a renal artery or vein, and scar tissue). For example, a surgeon may grasp all or a portion of the fibrous structure using the tip of a retractable hook and may then push the tissue into the sharp elbow of the hook. The surgeon may then oscillate the DDM and hook to cut tissue using a sharp edge inside the hook. The advantage of this method is that stress is applied at an intermediate location of the tissue that needs to be separated. In current practice, surgeons separate such tissues by a variety of techniques, including: the sides or ends of such tissue are simply grasped and pulled until they break. Sometimes, this can place large stresses on the pulled tissue (such as the intestinal wall), causing accidental tearing of critical tissue (such as the intestinal wall) (thereby perforating the intestine). By more locally and specifically stressing the tissue that needs to be separated (specifically, at the sharp elbow of the hook) rather than stressing a larger area of tissue (e.g., between two pairs of forceps), the surgeon can be more confident not to injure more distant tissue (e.g., the intestinal wall).

It is important to note that these methods of separating tissue by using oscillating hooks do not heat the tissue, in sharp contrast to the extreme heat generated by current practice using electrosurgery. The heat generated by electrosurgery is widely recognized as a major risk factor for subjecting surrounding tissue to accidental heat loss. Competing techniques for sharp dissection, such as ultrasound ablation (e.g., "harmonic shearing" from Ethicon Endosurgery), have been developed to reduce heat and thereby reduce the risk of heat loss to the tissue. However, the local heating is still quite severe and there is still a risk of heat loss. In contrast, as described herein, the use of an oscillating hook to separate the membrane or anatomical fibrous structure does not result in tissue heating, eliminating a major source of iatrogenic trauma.

FIG. 38 illustrates one embodiment of a differential dissecting instrument 3800 for use in laparoscopic surgery. It uses a mechanism to oscillate the DDM 3810 shown in fig. 34, 35A and 35B, including a retractable blade (not visible in this figure because it is in the retracted configuration). Differential dissecting instrument 3800 uses a pistol grip 3820 having a trigger for starting/stopping oscillation of DDM 3810 and a speed control 3840 for controlling the speed of the oscillation. The thumb activation button 3850 is used to extend the retractable blade held in the normally retracted configuration by a spring mechanism in the handle 3820. The rotator wheel 3860 may be contacted and rotated with an index finger, and rotation of the rotator wheel 3860 rotates the instrument insertion tube 3870 and the attached DDM 3810, which may rotate the oscillation plane 3880 of the DDM 3810 360 degrees, thereby enabling the surgeon to orient the oscillation plane 3880 with the tissue plane inside the body while maintaining good ergonomics of the handle 3820. Indicators 3862 on the rotating wheel 3860 provide visual cues to the surgeon external to the body for the orientation of the oscillation plane 3880, and similarly, visual cues such as embossed stripes can be placed on the instrument insertion tube 3870 or on the DDM 3810 to provide visual cues on the camera during laparoscopic viewing. The electrical plug 3890 enables optional attachment to an external electrosurgical generator via a cable for electrosurgical and electrocautery (controlled by an external foot pedal attached to the electrosurgical generator for controlling the electrosurgical generator, or, alternatively, a push button (not shown) may be placed on the handle 3820 for controlling the electrosurgical generator). Accordingly, differential dissecting instrument 3800 enables the surgeon to perform blunt dissection (via differential dissection), sharp dissection (via retractable hooks or electrosurgery), and coagulation (via electrocautery) with a single instrument, thereby reducing instrument changes that are complex for laparoscopic surgery.

Fig. 39 shows a differential dissecting instrument 3900 configured as a tool attached to a robotic arm of a Surgical Robot, such as a da Vinci Robot from Intuitive Surgical corporation. The DDM3610 is rotationally attached to the instrument insertion tube 3910 via a rotational joint 3630. Retractable hooks 3640 are movable between a retracted configuration and an extended configuration, as indicated by double arrow 3650. Retractable hooks 3640 have a tissue engaging surface 3660, a pointed end 3670 and an elbow 3680 with sharp edges for sharp dissection. Alternatively, the retractable hook 3640 may be electrically conductive and electrically connected to an external electrosurgical generator. Similarly, the DDM3610 or small conductive pads 3925 on the DDM3610 can be used for electrocautery. (note that conductive pads may be placed anywhere on the DDM3610, including the tissue-engaging surface 3690.) the instrument insertion tube 3910 is attached to a housing 3920 containing a motor to drive the DDM3610 and retractable hooks 3640 to oscillate, as previously described. The enclosure 3920 is configured with a receptacle 3930 having electrical and mechanical connections to a robotic arm of the surgical robot. Instrument insertion tube 3910 may be lengthened so that housing 3920 is positioned outside the patient's body. Instead, instrument insertion tube 3910 may be shortened, thereby positioning housing 3920 inside the patient's body with articulation joints located in the robotic arms and inside the patient's body to allow differential dissecting instrument 3900 to articulate inside the patient's body.

Placing a small motor in the housing near the DDM and inside the patient's body facilitates articulation of the instrument insertion tube of the differential dissecting instrument because all connections from the housing to the handle or housing through the articulation are electrical, which may be simpler than designs that require transmission of mechanical drive through the articulation. This is true for differential dissecting instruments designed for surgical robotics and laparoscopy. FIG. 40 illustrates one embodiment of the device as the tip of a laparoscopic differential dissecting instrument 4000. The DDM3610 fits over the retractable hooks 3640 and the conductive strips 3625. DDM3610 is rotationally attached to distal instrument insertion tube 4010, which instrument insertion tube 4010 is articulated to proximal instrument insertion tube 4020 at rotational joint 4030. Mounted inside the distal instrument insertion tube 4010 are a motor 4040 having a motor shaft 4050 and a solenoid 4060 having a solenoid plunger 4070. Rotation of the motor 4040 with the motor shaft 4050 drives the DDM 4010 and oscillation of the retractable hook 3640 as previously described. Solenoid 4060 is rigidly attached to distal instrument insertion tube 4010, while solenoid plunger 4070 is attached to motor 4040, which slides freely inside distal insertion tube 4010. Thus, when the solenoid 4060 is activated, the solenoid plunger moves up and down (in the direction indicated by arrow 4080), thereby driving the motor 4040, motor shaft 4050, and retractable hook 3640 up and down (as indicated by arrow 4080). The flexible conductor strip 4090 supplies the necessary power and signals to drive the motor 4040 and the solenoid 4060. Articulation of the laparoscopic differential dissecting instrument 4000 at the rotational joint 4030 bends the distal instrument insertion tube 4010 relative to the proximal instrument insertion tube 4020 as shown in the right hand panel. The distal instrument insertion tube 4010 can be driven in motion relative to the proximal instrument insertion tube 4020 by any of a variety of mechanisms, such as a control rod driven by a push-pull rod that is actuated by a manual mechanism located in the handle of the laparoscopic differential dissection instrument 4000. This configuration of the actuator (i.e., the motor 4040 and solenoid 4060) and flexible conductor strip 4090 facilitates the transmission of complex motions through the articulation at the rotary joint 4030 that would otherwise require complex mechanical components that are expensive, bulky, and prone to failure.

The embodiments set forth herein are examples and are not intended to be all inclusive. Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (27)

1. A differential dissecting instrument for differentially dissecting complex tissue, comprising:

a handle;

an elongated member having a first end and a second end, the first end connected to the handle;

a differential dissecting member configured to be rotatably attached to the second end, the differential dissecting member comprising at least one tissue engaging surface;

a mechanism configured to mechanically rotate the differential dissecting member about an axis of rotation to thereby move the at least one tissue engaging surface in at least one direction against the complex tissue;

wherein the at least one tissue engaging surface is configured to selectively engage the composite tissue such that upon pressing the differential dissecting member into the composite tissue, the at least one tissue engaging surface moves across the composite tissue and the at least one tissue engaging surface disrupts at least one soft tissue in the composite tissue, but does not disrupt hard tissue in the composite tissue.

2. The differential dissecting instrument of claim 1, wherein the tissue engaging surface further comprises protrusions extending outwardly from the tissue engaging surface, wherein the protrusions are configured to sweep through any gel-like material covering the array of tightly packed, organized fibrous components that are part of the hard tissue, the protrusions further configured to puncture and tear loosely packed fibrous components of the soft tissue, but slide out without puncturing the array of tightly packed, organized fibrous components in the hard tissue.

3. The differential dissecting instrument of claim 3, wherein the protrusions have a protrusion length of less than 1 mm.

4. The differential dissecting instrument of claim 3, wherein the protrusions have a protrusion length of less than 5 mm.

5. The differential dissecting instrument of claim 1, wherein the differential dissecting member further comprises a three-dimensional surface that does not have sharp edges such that the differential dissecting member will not cut into the composite tissue.

6. The differential dissecting instrument of claim 5, wherein the differential dissecting member does not have edges with a radius of curvature of less than 0.05 mm.

7. The differential dissecting instrument of claim 5, wherein the differential dissecting member does not have edges with a radius of curvature of less than 0.025 mm.

8. The differential dissecting instrument of claim 1, wherein the differential dissecting member further comprises at least one non-tissue engaging surface configured to contact the composite tissue, but not engage the composite tissue, so as not to disrupt the composition of the composite tissue.

9. The differential dissecting instrument of claim 8, wherein the non-tissue engaging surface is smooth.

10. The differential dissecting instrument of claim 1, further comprising:

at least one additional surface disposed laterally relative to the tissue engaging surface, wherein the at least one additional surface is configured to wedge the composite tissue as the differential dissecting instrument is pressed into the composite tissue, thereby tensioning and aligning a fibrous component of the at least one soft tissue perpendicular to the motion of the tissue engaging surface and promoting tearing of the fibrous component by the tissue engaging surface.

11. The differential dissecting instrument of claim 10, wherein the at least one additional surface comprises at least one surface on a shroud surrounding at least a portion of the differential dissecting member.

12. The differential dissecting instrument of claim 10, wherein the at least one additional surface comprises at least one non-tissue engaging surface on the differential dissecting member.

13. The differential dissecting instrument of claim 1, wherein the elongate member and the differential dissecting member are oriented relative to each other such that the axes of rotation of the elongate member and the differential dissecting member form a presentation angle that is non-zero for applying the tissue-engaging surface to a particular point on the composite tissue.

14. The differential dissecting instrument of claim 1, wherein the differential dissecting member is configured to oscillate at a speed in a range from 60 to 20000 cycles per minute.

15. The differential dissecting instrument of claim 1, wherein the differential dissecting member is configured to oscillate at a speed in a range from 2000 to 900000 cycles per minute.

16. The differential dissecting instrument of claim 1, wherein the differential dissecting member has a first end and a second end;

wherein the first end of the differential dissecting member is configured to be oriented away from the complex tissue and rotatably engage with the mechanism such that the differential dissecting member and thereby the second end of the differential dissecting member are rotated by the mechanism; and

wherein the second end of the differential dissecting member is configured to be oriented toward the complex tissue, the second end of the differential dissecting member comprising a semi-elliptical shape defined by three orthogonal half-axes including a semi-major axis A, a first semi-minor axis B, and a second semi-minor axis C, wherein C is parallel to the axis of rotation.

17. The differential dissecting instrument of claim 16, wherein the semi-major axis a is longer than the first and second semi-minor axes.

18. The differential dissecting instrument of claim 16, wherein the semi-major axis a, the first semi-minor axis B, and the second semi-minor axis C each have a different length.

19. The differential dissecting instrument of claim 1, wherein the differential dissecting member further comprises a tissue-engaging surface distributed over at least a portion of an outer surface of the body, and the tissue-engaging surface has:

a minimum placement radius R measured along a line perpendicular to the axis of rotation from the axis of rotation to a point on the tissue engaging surface nearest the axis of rotation_min，

A maximum placement radius R measured along a line perpendicular to the axis of rotation from the axis of rotation to a point on the tissue engaging surface furthest from the axis of rotation_max，

The minimum placement radius R_minGreater than zero.

20. The differential dissecting instrument of claim 19, wherein the minimum placement radius R_minWith the maximum radius of placement R_maxThe difference is equal to or greater than R_max5% of (i), (R)_max- R_min) ≥ 0.05*R_max。

21. The differential dissecting instrument of claim 19, wherein the minimum placement radius R_minWith the maximum radius of placement R_maxThe difference is equal to or greater than the average length P of the protrusions_avgI.e., (R)_max- R_min) ≥ P_avg。

22. The differential dissecting instrument of claim 19, wherein R_maxGreater than 1mm but less than 100 mm.

23. The differential dissecting instrument of claim 19, wherein R_maxGreater than 0.5 mm butLess than 5 mm.

24. The differential dissecting instrument of claim 1, wherein the differential dissecting member is further configured to expose a retractable hook configured to be movable between a first retracted configuration and a second extended configuration and configured to be electrically conductive and electrically connected to an external electrosurgical generator.

25. The differential dissecting instrument of claim 1, wherein the differential dissecting instrument is configured as a tool attachable to an arm of a surgical robot.

26. The differential dissecting instrument of claim 25, further comprising a housing having at least one socket having at least one of an electrical connector and a mechanical connector configured to attach to the arm of the surgical robot.

27. The differential dissecting instrument of claim 26, further comprising at least one articulation configured to be located inside a patient's body during use of the differential dissecting instrument, the at least one articulation configured to allow the differential dissecting instrument to articulate inside the patient's body.