US20100179556A1 - Methods for placing materials into bone - Google Patents

Abstract

Cancellous bone is accessed through a subcutaneous access path in soft tissue. A cavity is formed in cancellous bone by a cavity forming tool that is advanced through the subcutaneous access path into cancellous bone and manipulated to form the cavity. A measured volume of bone filling material is delivered into the cavity through the subcutaneous access path by a nozzle having an interior bore defining an interior volume sized for containing bone filling material, which is advanced through the subcutaneous access path. A nested instrument is formed while clearing residual bone filling material from the interior bore by an auxiliary tool that can be manipulated independently of the nozzle, which is advanced through the interior bore of the nozzle.

Description

RELATED APPLICATIONS
• This application is a divisional of co-pending U.S. patent application Ser. No. 10/617,976, filed Jul. 11, 2003, and entitled “Systems and Methods for Placing Materials into Bone,” which is, a divisional of U.S. patent application Ser. No. 09/804,107, filed Mar. 12, 2001, now U.S. Pat. No. 6,613,054, which is a divisional of U.S. patent application Ser. No. 09/134,323, filed Aug. 14, 1998, now U.S. Pat. No. 6,241,734.
FIELD OF THE INVENTION
• The invention generally relates to the treatment of bone conditions in humans and other animals.
BACKGROUND OF THE INVENTION
• Injection devices similar to a household caulking gun are used to inject bone cement into bone. A typical bone cement injection device has a pistol shaped body, which supports a cartridge containing bone cement. A trigger actuates a spring-loaded ram, which forces a volume of bone cement in a viscous condition through a suitable nozzle and into the interior of a bone targeted for treatment. According to the teachings of U.S. Pat. Nos. 4,969,888 and 5,108,404, a cavity can be first formed by compacting cancellous bone inside the bone, into which the bone cement is injected. Conventional cement injection devices provide no opportunity to override the spring action and quickly terminate the flow of cement, should the cavity fill before the spring-actuated load cycle is completed. Furthermore, once the spring-actuated mechanism, is triggered, conventional cement injection devices do not permit the injection volume or inject rate to be adjusted or controlled in real time, in reaction to cancellous bone volume and density conditions encountered inside bone.
• In a clinical procedure called vertebroplasty, bone cement is injected at high pressure (typically, about 700 psi) into the interior of a vertebral body, without the prior formation of a cavity. Because high pressure is used, there is little opportunity to quickly and accurately adjust cement flow in reaction to bone volume and density conditions encountered. Momentum generated by high pressure-induced cement flow continues to propel cement into the targeted bone site even after termination of the high pressure.
• As a result of the relatively high pressure that conventional procedures rely upon, coupled with the effective lack of a short response time, the targeted bone interior can suddenly overfill. Excess filling material can be forced outside the bone interior, and into adjoining tissue regions, where the presence of filling material is not required or desired.
• For these and other reasons, there is a need for new systems and methods for placing material into bones, with greater rate and volume control, a faster response time, and without requiring the use of high pressure.
SUMMARY OF THE INVENTION
• The invention provides instruments, systems, and methods, which, in use, enable greater control over the placement of materials into bone.
• One aspect of the invention provides a method that accessed cancellous bone through a subcutaneous access path in soft tissue. A cavity is formed in cancellous bone by a cavity forming tool that is advanced through the subcutaneous access path into cancellous bone and manipulated to form the cavity. A measured volume of bone filling material is delivered into the cavity through the subcutaneous access path by a nozzle having an interior bore defining an interior volume sized for containing bone filling material, which is advanced through the subcutaneous access path. A nested instrument is formed while clearing residual bone filling material from the interior bore by an auxiliary tool that can be manipulated independently of the nozzle, which is advanced through the interior bore of the nozzle.
• The bone filling material can comprise medication or a material that sets to a hardened condition e.g., bone cement, or autograft tissue, or allograft tissue, or synthetic bone substitute, or combinations thereof.
• Features and advantages of the inventions are set forth in the following Description and Drawings, as well as in the appended Claims.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a plane view of a kit housing a system of functional instruments, which, in use, gain subcutaneous access to the inside of a bone to compact cancellous bone and form a cavity for therapeutic purposes;
• FIG. 2 is an exploded perspective view of the kit shown inFIG. 1;
• FIG. 3 is a perspective view of the subcutaneous access instrument group that forms a part of the system shown inFIG. 1;
• FIG. 4A is a perspective view of the cavity forming instrument that forms a part of the system shown inFIG. 1;
• FIG. 4B is a section view of the catheter tube of the cavity forming instrument, taken generally alongline4B-4B inFIG. 1;
• FIG. 4C is an end view of an alternative embodiment of the cavity forming instrument shown inFIG. 4A, having a prebent stylet;
• FIG. 5 is a perspective view of the material introducing instrument group that forms a part of the system shown inFIG. 1;
• FIGS. 6 and 7 are, respectively, top and side views of a human vertebral body;
• FIG. 8 is a top view of a vertebral body during insertion of a spinal needle instrument to begin a bone access procedure;
• FIGS. 9 to 11 are top views showing subsequent steps, after insertion of the spinal needle instrument shown inFIG. 8, of inserting a guide pin instrument into the vertebral body;
• FIG. 12 is a perspective view showing a subsequent step, after insertion of the guide pin instrument shown inFIGS. 9 to 11, which deploys an obturator instrument deployed over the guide pin instrument with aid of a handle;
• FIG. 13 is a top view of the vertebral body, with the obturator instrument shown inFIG. 12 deployed;
• FIG. 14 is a perspective view showing a subsequent step, after insertion of the obturator instrument shown inFIG. 12, which uses the handle shown inFIG. 12 to aid in the deployment of a cannula instrument over the obturator instrument;
• FIG. 15 is a top view of the vertebral body, with the cannula instrument shown inFIG. 14 deployed;
• FIG. 16 is a perspective view showing a subsequent step, after insertion of the cannula instrument shown inFIG. 14, which removes the obturator instrument from the cannula instrument, to leave the cannula instrument and guide pin instrument in place;
• FIG. 17 is a top view of the vertebral body, after the obturator removal step shown inFIG. 16, leaving the cannula instrument and guide pin instrument in place;
• FIG. 18 is a perspective view showing a subsequent step, after removal of the obturator instrument shown inFIG. 16, which uses the handle shown inFIG. 14 to aid in the deployment of a drill bit instrument through the cannula instrument along the guide pin instrument;
• FIG. 19 is a top view of the vertebral body, as the drill bit instrument shown inFIG. 18 is deployed with aid of the handle to open a passage into the interior volume of the vertebral body;
• FIG. 20 is a perspective view showing a subsequent step, after removal of the drill bit instrument and guide pin instrument shown inFIG. 18, of deploying the cavity forming instrument into the vertebral body;
• FIG. 21 is a top view of the vertebral body, as the expandable structure carried by the cavity forming instrument shown inFIG. 20 is deployed into the interior volume of the vertebral body;
• FIG. 22 is a top view of the vertebral body, as the expandable structure shown in a collapsed condition inFIG. 21 is expanded to compact cancellous bone and form a cavity;
• FIG. 23 is a top view of the vertebral body, after removal of the expandable structure, showing the cavity formed by compacting cancellous bone;
• FIG. 24 is a perspective view of the syringe of the material introducing instrument group, shown inFIG. 5, being filled with a material selected for introduction into the cavity shown inFIG. 23;
• FIG. 25 is a perspective view of the syringe shown inFIG. 24 being joined to a nozzle, which also forms a part of the material introducing instrument group shown inFIG. 5;
• FIG. 26 is a perspective view showing the syringe and attached nozzle shown inFIG. 25 being deployed through the cannula instrument in preparation of introducing material into the cavity;
• FIGS. 27 and 28 are perspective and top views, respectively, showing the syringe and attached nozzle shown inFIG. 26 in use to inject material into the cannula instrument for passage into the cavity;
• FIG. 29 is a top view of the vertebral-body after a measured volume of material has been injected and the syringe and attached nozzle withdrawn from the cannula instrument;
• FIG. 30 is a top view showing the deployment of a tamping instrument, which forms a part of the material introducing instrument group shown inFIG. 5, being deployed in the cannula instrument;
• FIG. 31 is a top view showing advancement of the tamping instrument in the cannula instrument to displace and distribute material from the cannula instrument into the cavity;
• FIG. 32 is a top view of the vertebral body after removal of the tamping instrument and cannula instrument, showing the cavity, now filled with the material;
• FIG. 33 is a perspective view of a reduced diameter cannula instrument and associated reduced diameter material introducing instruments, which embody features of the invention;
• FIG. 34 is a perspective view of a cavity forming instrument having an expandable cavity forming structure, which, in use, is deployed using the reduced diameter cannula instrument shown inFIG. 33, the cavity forming instrument having a sliding introducer sleeve shown in its rearward position;
• FIG. 35 is a perspective view of the cavity forming instrument shown inFIG. 34, with the introducer sleeve moved forward to overlie and compress the expandable cavity forming structure;
• FIG. 36 is a perspective view of the cavity forming structure shown inFIG. 35, with the introducer sleeve (shown partially in section) coupled to the proximal end of the cannula instrument, to guide the expandable structure compressed within the sleeve into the reduced diameter cannula instrument without damage; and;
• FIG. 37 is a perspective view of the cavity forming structure shown inFIG. 36, after the expandable structure has been guided by the introducer sleeve into the cannula instrument and is being advanced through the cannula instrument for deployment in bone.
• The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• FIGS. 1 and 2 show asystem10 of functional instruments. In use, certain instruments of thesystem10 are deployed in a purposeful manner to penetrate tissue and gain subcutaneous access to the inside of a bone. Inside bone, other instruments of thesystem10 are deployed to form a cavity in cancellous bone, into which a material is placed for therapeutic purposes.
• In the illustrated embodiment, thesystem10 is arranged as aprepackage kit12 in threefunctional instrument groups14,16, and18. The first group14 (whichFIG. 3 shows outside the kit12) comprises instruments whose purpose is to gain subcutaneous access to a bone interior. The second group16 (whichFIG. 4 shows outside the kit12) an instrument whose function is to create a cavity in cancellous bone. The third group18 (whichFIG. 5 shows outside the kit12) comprises instruments whose function is to introduce a material into the cavity.
• Thekit12 can take various forms. In the illustrated embodiment, thekit12 comprises a sterile, wrapped assembly.
• Further details of eachfunctional instrument group14,16, and18 and thekit12 follow.
I. The Subcutaneous Access Instrument Group
• The number and type of instruments in thegroup14 can vary.FIG. 3 shows five representative instruments, each having a different size and function.
• A. The Spinal Needle and Guide Pin
• AsFIG. 3 shows, one instrument comprises a conventionalspinal needle assembly20 and aguide pin instrument26.
• In use, thespinal needle assembly20 establishes the initial subcutaneous path leading to the targeted treatment site. Theguide pin instrument26 is deployed through this path, followed by progressively larger instruments, as will be described later.
• Thespinal needle assembly20 comprises astylet22, which is slidably deployed within astylus24. Thestylus24 typically has, for example, about an eleven gauge diameter. Other gauge diameters can be used, according to the gauge of theguide pin instrument26 used.
• In use, theguide pin instrument26 is deployed through the subcutaneous path established by thespinal needle assembly20, by exchange with theneedle stylet22. Theguide pin instrument26 serves to guide the establishment of the main operative pathway to the targeted treatment site.
• The remaininginstruments28,30, and32 in thegroup14 share some common features, although they are intended, in use, to perform different functions. Theseinstruments28,30, and32 are each made of a rigid, surgical grade plastic or metal material. Theseinstruments28,30, and32 each comprises an elongated, cylindrical body having aproximal end34 and adistal end36.
• B. The Obturator Instrument
• Theinstrument28 functions as an obturator. Itsdistal end36 is tapered to present a penetratingsurface38. In use, thesurface38 is intended to penetrate soft tissue in response to pushing or twisting forces applied by the physician at theproximal end34.
• Theproximal end34 of theobturator instrument28 presents aflanged surface40, which tapers from a larger outer diameter to a smaller outer diameter in the direction of theproximal end34. Theflanged surface40 includes an array of circumferentially spacedteeth42.
• Aninterior lumen44 extends through theobturator instrument28 from thedistal end36 to theproximal end34. Theinterior lumen44 is sized to accommodate theguide pin instrument26, as will be described in greater detail later.
• C. The Cannula Instrument
• Theinstrument30 functions as a cannula or guide sheath. Thecannula instrument30 is somewhat larger in diameter than and not as long as theobturator instrument28. Thecannula instrument30 includes aninterior lumen46 that extends from itsdistal end36 to itsproximal end34. Theinterior lumen46 is sized to accept theobturator instrument28. The size of theinterior lumen46 permits a physician to slide and rotate thecannula instrument30 relative to theobturator instrument28, and vice versa, as will be described in greater detail later.
• Thedistal end36 of thecannula instrument30 presents anend surface48. In use, theend surface48 of thecannula instrument30 is intended to penetrate soft tissue surrounding theobturator instrument28 in response to pushing or twisting forces applied at theproximal end34.
• Theproximal end34 carries anenlarged fitting50. The fitting50 tapers from a larger diameter to a smaller diameter in the direction of theproximal end34. Like the taperedflange40 on theobturator instrument28, thetapered fitting50 has an array of circumferentially spacedteeth52. Thetapered fitting50 of thecannula instrument30 possesses a larger maximum outer diameter than the maximum outer diameter of the taperedflange40 of theobturator instrument28.
• Thecannula instrument30 includes measuredmarkings118 along its length (seeFIG. 3). The measuredmarkings118 gauge the depth of insertion. Themarkings118 can be placed, for example, at one centimeter intervals. AsFIG. 3 shows, themarkings118 can be consecutively numbered, beginning at thedistal end36, so that the physician can ascertain the insertion depth at a glance.
• D. The Drill Bit Instrument
• Theinstrument32 functions as a drill bit. Thedrill bit instrument32 has generally the same physical dimensions as theobturator instrument28. Like theobturator instrument28, thedrill bit instrument32 is intended, in use, to fit for sliding and rotational movement within theinterior lumen46 of thecannula instrument30.
• Thedistal end36 of the drill bit instrument includes machined cutting edges54. In use, the cutting edges54 are intended to penetrate hard tissue in response to rotation and longitudinal load forces applied at theproximal end34 of thedrill bit instrument32.
• Theproximal end34 presents a taperedflange56, which is substantially identical to theflange40 on theobturator instrument28. Like theobturator instrument28, the taperedflange56 changes from a larger diameter to a smaller diameter in the direction of theproximal end34. The taperedflange56 of thedrill bit instrument32 also includes an array of circumferentially spacedteeth58. The form and orientation of theteeth58 on thedrill bit instrument32 correspond to the form and orientation of theteeth42 on theobturator instrument28.
• E. The Handle
• The group includes ahandle60. Thehandle60 engages thefunctional instruments28,30, and32 in a removable, slip fit fashion to aid a physician in manipulating the instruments during use.
• Thehandle60 is made from a molded or cast rigid plastic or metal material. Thehandle60 is shaped to be comfortably and securely grasped by a normal human hand. The shape and size to accommodate this function can, of course, vary. In the illustrated embodiment, thehandle60 is elongated along a main axis to fit comfortably across the palm of the hand.
• Thehandle60 includes acenter post62, which is integrally molded to thehandle60 about its geometric center. Thecenter post62 extends downward to give the handle60 a general T-shape.
• Thehandle60 includes two interior cavities orsockets64 and66 in thecenter post62. The sockets guide the attachment between thehandle60 and theinstruments28,30, and32. The first andsecond sockets64 and66 are sized to present unique attachment sites for different functional instruments.
• Thefirst socket64 includes an array of circumferentially spacedgrooves68, which, in form and orientation, match theteeth42 and58 at the proximal ends34 of theobturator instrument28 and thedrill bit instrument32. Thefirst socket64 accepts the taperedflange40 or56 of either theobturator instrument28 or thedrill bit instrument32. Theteeth42 and58 of either taperedflange40 or56 mesh in a slip-fit with thegrooves68 of thefirst socket64. The running slip-fit allows longitudinal force to be applied to eitherinstrument28 or32 through thehandle60. The running slip-fit also prevents relative rotation between eitherinstrument28 or32 and thefirst socket64, thereby permitting torsional or twisting forces to be applied to eitherinstrument28 or32 by thehandle60, with an increased mechanical advantage.
• Thesecond socket66 is larger than thefirst socket64 and is sized to accept the larger tapered fitting50 of thecannula instrument30. Thesecond socket66 includes an array of circumferentially spacedgrooves70, which, in form and orientation, match theteeth52 on thetapered fitting50. Theteeth52 of thetapered fitting50 mesh in a slip-fit with thegrooves70 of thesecond socket66. The running slip-fit allows both longitudinal and torsional forces to be applied to thecannula instrument30 through thehandle60, with increased mechanical advantage.
• As shown in phantom lines inFIG. 3, afirst passage72 extends through the top of thehandle60, through thecenter post62, and into thefirst socket64. Thepassage72 is generally aligned with the center of thefirst socket64 and is sized to pass the guide pin instrument26 (seeFIG. 12).
• Likewise, as also shown in phantom lines inFIG. 3) asecond passage74 extends through the top of thehandle60, through thecenter post62, and into thesecond socket66. Thepassage74 is generally aligned with the center of thesecond socket66 and is sized to pass the eitherobturator instrument28 or the drill bit instrument32 (seeFIG. 14).
• Further details of thehandle60 can be found in co-pending U.S. patent application Ser. No. 09/014,229, filed Jan. 27, 1998, and entitled AA Slip-Fit Handle for Hand-Held Instruments that Access Interior Body Regions.
• Further details regarding the use of thehandle60 and the associatedinstruments26,28, and30 will be provided later.
II. The Cavity Forming Instrument
• AsFIG. 4A shows; thegroup16 includes aninstrument76, which is deployed through thecannula instrument30 to a location inside bone (seeFIG. 20). When so deployed, theinstrument76 serves to form a cavity in cancellous bone.
• Theinstrument76 can be constructed in various ways. In the illustrated embodiment, theinstrument76 includes aflexible catheter tube78 having aproximal end80 and adistal end82. Theproximal end80 carries ahandle grip84 to facilitate gripping and maneuvering thecatheter tube78. The materials for thecatheter tube78 are selected to facilitate its advancement through thecannula instrument30. Thecatheter tube78 can be constructed, for example, using standard flexible, medical grade plastic materials, like vinyl, nylon, polyethylenes, ionomer, polyurethane, and polyethylene tetraphthalate (PET). Thecatheter tube78 can also include more rigid materials to impart greater stiffness and thereby aid in its manipulation. More rigid materials that can be used for this purpose include stainless steel, nickel-titanium alloys (NitinolJ material), and other metal alloys.
• Thedistal end82 of theinstrument76 carries anexpandable structure86. In the illustrated embodiment, theexpandable structure86 is made from a polyurethane or an elastomer (e.g., silicone or nylon) material. Thestructure86 has been preformed to possess a desired shape by exposure to heat and pressure, e.g., through the use of conventional thermoforming techniques.
• AsFIG. 4B shows, thecatheter body78 includes aninterior lumen88, which communicates with the interior of thestructure86. A fitting90 on theproximal end80 of the catheter tube78 (seeFIG. 48) communicates with thelumen88. The fitting90 couples thelumen88 to asource92 of fluid, sterile saline (seeFIG. 21), or a radiopaque contrast medium.
• The fluid is introduced from thesource92 into thestructure86 under positive pressure, causing thestructure86 to expand. During expansion inside bone, the material selected for thestructure86 preferably resists deformation, so that the expanded shape inside bone essentially corresponds to its expanded shape outside bone, i.e., when in an open air environment. This allows the physician to select in an open air environment astructure86 having an expanded shape desired to meet the targeted therapeutic result, with the confidence that the expanded shape inside bone will be similar in important respects. In addition to being able to expand its volume while resisting deformation inside bone, the material of thestructure86 preferable withstands abrasion, tearing, and puncture when in contact with cancellous bone.
• The shape of thestructure86, when expanded inside bone, is selected by the physician, taking into account the morphology and geometry of the site to be treated. The shape of the cancellous bone to be compressed, and the local structures that could be harmed if bone were moved inappropriately, are generally understood by medical professionals using textbooks of human skeletal anatomy along with their knowledge of the site and its disease or injury. The physician is also able to select the expanded shape inside bone based upon prior analysis of the morphology of the targeted bone using, for example, plain film x-ray, fluroscopic x-ray, or MRI or CT scanning. The expanded shape inside bone is selected to optimize the formation of a cavity that, e.g., when filled with a suitable material, provides support across the region of the bone being treated.
• As one general guideline, in cases where the bone disease causing fracture (or the risk of fracture) is the loss of cancellous bone mass (as in osteoporosis), the selection of the expanded shape of thestructure86 inside bone should take into account that from 30% to 90% of the cancellous bone volume should be compacted. Another general guideline is the amount that the targeted fractured bone region has been displaced or depressed. The expansion of thestructure86 within the cancellous bone region inside a bone can elevate or push the fractured cortical wall back to or near its anatomic position occupied before fracture occurred.
• In the illustrated embodiment (seeFIG. 4A), thestructure86 possesses a preformed hour-glass or peanut shape. This shape is selected in contemplation of deploying thestructure86 in a vertebral body, as will be described in greater detail later.
• To facilitate deployment of thestructure86 through thecannula instrument30, thecatheter tube78 includes a secondinterior lumen94. Thelumen94 extends from asecond fitting98 on theproximal end80 of thecatheter tube78, through the body of thecannula tube78, and through the interior of the thetip end172 of thestructure86. Thelumen94 receives a generallystiff stylet96, which can be made from a molded plastic or stainless steel material. Thestylet96 is inserted through the fitting98 into thelumen94, and includes a threadedcoupling100 to secure thestylet96 against movement. The presence of thestylet96 serves to keep thestructure86 in the desired distally straightened condition during passage through thecannula instrument30 into the targeted tissue region. Once thestructure86 is free of thecannula instrument30 and inside bone, thestylet96 can be withdrawn (shown byarrow174 inFIG. 4A). This returns normal flexibility to thecatheter tube78 and facilitates manipulation of thestructure86 inside bone. With thestylet96 withdrawn, thelumen94 can also serve as a pathway for introducing rinsing liquid or to aspirate debris from the bone.
• In the illustrated embodiment, thestylet96 is biased toward a generally straight condition. In an alternative embodiment (seeFIG. 4C), astylet102 can have a preformed memory, to normally bend its distal region. The memory is overcome to straighten thestylet102 when confined within thecannula instrument30. However, as thestructure86 and distal region of the preformedstylet102 advance free of thecannula instrument30, to pass into the targeted region, the preformed memory bends the distal region of thestylet102 and thereby shifts the main axis of theexpandable structure86. Theprebent stylet102, positioned within the interior of thestructure86, aids in altering the orientation of thestructure86, bringing it into better anatomic alignment with the targeted region.
• Other types of instruments that can form cavities in cancellous bone and other interior body regions are described in co-pending U.S. patent application Ser. No. 09/055,805, entitled AStructures and Methods for Creating Cavities in Interior Body Regions,@ filed Apr. 6, 1998.
III. The Material Introducing Instrument Group
• Thegroup18 includesinstruments104,106, and108 which serve to convey and compact a selected material inside the cavity formed by thestructure86. The material in the cavity provides a desired therapeutic result, e.g., replacement of tissue mass, or renewed interior support for the bone, or the delivery of medication, or combinations thereof. Accordingly, the material to perform this function can be selected from among, e.g., a material that sets to a hardened condition, including bone cement, autograft tissue, allograft tissue, synthetic bone substitute, as well as a medication, or combinations thereof.
• In the illustrated embodiment, thegroup18 comprisesmaterial injection instruments104 and106 and amaterial tamping instrument108, which deliver material at a low delivery pressure, i.e., a pressure no greater than about 360 psi.
• A. Low Pressure Material Injection Instruments
• In the illustrated embodiment, the material is injected by use of aconventional syringe104, to which a specially designedinjection nozzle106 is coupled. A manual actuated syringe with a push plunger can be used. Alternatively, a LeVeen Inflation Syringe with threaded plunger can be used, which can be actuated manually or by use of a mechanical actuator.
• In the illustrated embodiment, thesyringe104 is made from a clear plastic material. Thesyringe104 includes achamber110, which receives the material to be injected. The material is expressed from thechamber100 by a manually advanced syringe piston112 (see alsoFIG. 25).
• Theinjection nozzle106 connects by a threadedconnector114 to the end of the syringe104 (see alsoFIG. 25). In the illustrated embodiment, thenozzle106 is made from a generally flexible, inert plastic material, such as such as polyethylene or another suitable polymer. Alternatively, thenozzle106 can be made from a generally rigid plastic or metal material.
• Theinjection nozzle106 is sized to be advanced through the cannula instrument30 (seeFIG. 26). Thenozzle106 includes measuredmarkings116 along its length. Themarkings116 can be placed, for example, at one centimeter intervals, to correspond with themarkings118 on thecannula instrument30, so that the relative position of thenozzle106 within thecannula instrument30 can be gauged. Themarkings118 can, e.g., include aset point176. Alignment of theset point176 at theproximal end34 of thecannula instrument30, indicates that the distal end of thenozzle106 is located in an aligned relationship with thedistal end36 of thecannula instrument30. In this arrangement, themarkings118 are consecutively numbered with positive numbers proximally of theset point176 and with negative numbers distally of theset point176. The physician is thereby able to tell at a glance the location of the distal end of thenozzle106, in terms of how far beyond or short of thedistal end36 of thecannula instrument30 it is.
• In use, the distal end of thenozzle106 is located beyond thedistal end36 of thecannula instrument30 within the cavity formed in the targeted tissue region. AsFIG. 5 shows, the distal end of thenozzle106, when made from a plastic material, can carry at least oneradiopaque marker208, to enable remote visualization of the nozzle position within the body. Thesyringe104 elects a predetermined volume of material into thenozzle106 in a low pressure stream into the cavity. As the material fills the cavity, the nozzle (still ejecting material) is retracted from the cavity and into thecannula instrument30 itself. Further details of this function and result will be provided later.
• B. The Material Tamping Instrument
• Thegroup18 also includes amaterial tamping instrument108. The tampinginstrument108 is made from generally rigid, inert plastic or metal material. The tampinginstrument108 is also sized to be advanced into the cannula instrument30 (seeFIG. 30). Thefree end124 of the tampinginstrument108 is ribbed or contoured to facilitate gripping theinstrument108 during use.
• The tampinginstrument108 includes measuredmarkings122 along its length. Themarkings116 can be placed, for example, at one centimeter intervals, to correspond with themarkings118 on thecannula instrument30, so that the relative position of the tampinginstrument108 within thecannula instrument30 can be gauged. Like thenozzle106, themarkings122 on the tampinginstrument108 includes aset point178, which indicates when the distal end of the tampinginstrument108 aligns with thedistal end36 of thecannula instrument30. Also like thenozzle106, themarkings122 on the tampinginstrument108 are consecutively numbered with positive numbers proximally of theset point178 and with negative numbers distally of theset point178. The physician is thereby able to tell at a glance the location of the end of the tampinginstrument108, in terms of how far beyond or short of thedistal end36 of thecannula instrument30 it is. AsFIG. 5 also shows, the end of the tampinginstrument108, when made from a plastic material, can carry at least oneradiopaque marker210, so that its position can be visualized from outside the body.
• After withdrawal of thenozzle106 from thecannula instrument30, residual material is left in thecannula instrument30. The purpose of the tampinginstrument108 is to displace the residual material out thedistal end36 of thecannula instrument30 and into the cavity, to thereby fill the cavity without exerting undue pressure within the bone. The tampinginstrument108 thereby serves to clear residual material from thecannula instrument30, to assure that the desired volume of material is delivered into the cavity. The removal of residual material from thecannula instrument30 by the tampinginstrument108 also prevents seepage of material into surrounding tissue regions upon removal of thecannula instrument30. The tampinginstrument108 also compacts the material uniformly within the cavity, again without undue pressure. Further details of these functions and results will be discussed later.
IX. The Kit
• AsFIGS. 1 and 2 show, in the illustrated embodiment, thekit12 includes aninterior tray126 made, e.g., from die cut cardboard, plastic sheet, or thermo-formed plastic material. Thetray126 includes spaced aparttabs128, which hold the various instruments in a secure position during sterilization and storage prior to use.
• When packaged as a sterile assembly, thekit12 includes aninner wrap130, which is peripherally sealed by heat or the like, to enclose thetray126 from contact with the outside environment. One end of the inner wrap includes a conventional peal-away seal132, to provide quick access to thetray126 at the instant of use, which preferably occurs in a sterile environment, such as within an operating room.
• When packaged as a sterile assembly, thekit12 also includes anouter wrap134, which is also peripherally sealed by heat or the like, to enclosed theinner wrap130. One end of the outer wrap includes a conventional peal-away seal136, to provide access to theinner wrap130 and its contents. Theouter wrap134 can be removed from the inner wrap in anticipation of imminent use, without compromising sterility of the contents of thekit12.
• AsFIG. 2 shows, each inner andouter wrap130 and134 includes a peripherally sealedtop sheet138 andbottom sheet140. In the illustrated embodiment, thetop sheet138 is made of transparent plastic film, like polyethylene or MYLAR7 material, to allow visual identification of the contents of thekit12. Thebottom sheet140 is made from a material that is permeable to ETO sterilization gas, e.g., TYVEK7 plastic material (available from DuPont).
• In the illustrated embodiment, thetray126 presents theinstruments groups14,16, and18 in an ordered, organized layout, which is arranged to aid the physician in carrying out the intended procedure. For example, the layout of thetray126 can present theinstruments groups14,16, and18 in top-to-bottom order, according to sequence of intended use. For example, in a typical bone access procedure (as will be demonstrated in greater detail later), thestylet22 andstylus24 of thespinal needle assembly20 are deployed first, followed by theguide pin instrument26, followed by theobturator instrument28, then thecannula instrument30, then thedrill bit instrument32, then thecavity forming instrument76, then thesyringe104 andnozzle106 Instruments, and lastly the tampinginstrument108. Accordingly, thetray126 packages these instruments and components in a top-to-bottom order, with thespinal needle assembly20 topmost, theguide pin instrument26 next, theobturator instrument28 next, and so on, with the tampinginstrument108 lowermost on thetray126.
• In this layout, thehandle60 is packaged to the side of theaccess instrument group14. Thetray126 can include written labels (not shown) identifying the components contained in thekit12.
• Thekit12 also preferably includes in thetray126directions144 for using the contents of the kit to carry out a desired procedure. An exemplary procedure which thedirections144 can describe will be explained later.
• When packaged as a sterile assembly, thedirections144 can also include the statement “For Single Patient Use Only” (or comparable language) to affirmatively caution against reuse of the contents of thekit12 whose performance characteristics and efficacy degrade after a single use. Thespinal needle assembly20, thecavity forming instrument76, and thematerial introducing instruments104,106, and108 should, for these reasons, be used but a single time and then discarded. Thedirections144 also preferably affirmatively instruct against resterilization of at least these contents ofkit12, and also instructs the physician to dispose of at least these contents of thekit12 upon use in accordance with applicable biological waste procedures.
• The presence of theinstrument groups14,16, and18 packaged in thesterile kit12 verifies to the physician that the contents are sterile and have not been subjected to prior use. The physician is thereby assured that the instrument groups meet established performance and sterility specifications.
• It should be appreciated that the various instruments contained in thekit12 can be packaged into several, smaller functional kits. For example, a first kit can package theaccess instrument group14, a second kit can package the cavity forminginstrument group16, and a third kit can package the materialintroduction instrument group18,FIGS. 1 and 2 illustrate one of many different possible embodiments.
V. Illustrative Use of the System
• The following describes use of theinstrument groups14,16, and18 packaged in thekit12 in the context of treating bones. This is because the instruments of thegroups14,16, and18 can be advantageously used for this purpose. Still, it should be appreciated that one or more of the instrument groups, used alone or in association with other instruments, can perform other diagnostic or therapeutic functions in other interior regions of the body.
• In particular, theinstrument groups14,16, and18 will described with regard to the treatment of human vertebra. It should be appreciated, however, their use is not limited to human vertebrae. The instrument groups14,16, and18 can be used in association with hand-held instruments in the treatment of diverse human or animal bone types.
• A. The Vertebral Body
• AsFIGS. 6 and 7 show, atypical vertebra146 includes avertebral body148, which extends on the anterior (i.e., front or chest) side of thevertebra146.
• Thevertebral body148 has the shape of an oval disk. Thevertebral body148 includes an exterior formed from compactcortical bone150. Thecortical bone150 encloses an interior volume of reticulated cancellous, or spongy, bone152 (also called medullary bone or trabecular bone).
• Thespinal cord154 passes through thespinal canal156 of thevertebra146. The vertebral arch158 surrounds thespinal canal156. Thepedicles160 of the vertebral arch158 adjoin thevertebral body148. Thespinous process162 extends from the posterior of the vertebral arch158, as do the left and righttransverse processes164.
• B. Treatment of a Vertebral Body
• During a typical procedure, a patient lies on an operating table. The patient can lie face down on the table, or on either side, or at an oblique angle, depending upon the physician's preference.
• The physician or surgical assistant removes the outer andinner wraps130 and134 of thekit12, exposing thetray126 for use. The physician acquires thespinal needle assembly20 from thetray126. AsFIG. 8 shows, the physician introduces thespinal needle assembly20 into soft tissue ST in the patient's back. Under radiologic or CT monitoring, the physician advances thespinal needle assembly20 through soft tissue down to and into the targetedvertebra146. The physician will typically administer a local anesthetic, for example, lidocaine, throughassembly20. In some cases, the physician may prefer other forms of anesthesia.
• The physician directs thespinal needle assembly20 to penetrate thecortical bone150 and thecancellous bone152 of the targetedvertebral body148. Preferably the depth of penetration is about 60% to 95% of thevertebral body148.
• FIG. 8 shows gaining, access to cancellous bone through the side of thevertebral body148, which is called postero-lateral access. However, access may be indicated through apedicle160, which is called transpedicular access. The type of access is based upon the objectives of the treatment or for other reasons, based upon the preference of the physician.
• AsFIG. 9 shows, after positioning thespinal needle assembly20 incancellous bone152, the physician holds thestylus24 and withdraws thestylet22. The physician acquires theguide pin instrument26 from thetray126. AsFIG. 10 shows, while still holding thestylus24, the physician slides theguide pin instrument26 through thestylus24 and into thecancellous bone152. The physician now removes the stylus24 (seeFIG. 11), leaving theguide pin instrument26 deployed within thecancellous bone152.
• The physician next acquires theobturator instrument28 and thehandle60 from thetray126. The physician slides theobturator instrument28 over theguide pin instrument26, distal end first. The physician slides theguide pin instrument26 through thefirst passage72 and thefirst socket64 of thehandle60. AsFIG. 12 shows, the physician slides thehandle60 along theguide pin instrument26 toward the taperedflange40 of theobturator instrument28, until achieving a running slip-fit between thefirst socket64 and the taperedflange40, in the manner previously described. Theobturator instrument28 is now ready for use.
• AsFIG. 12 shows, the physician makes a small incision I in the patient's back. The physician twists thehandle60 while applying longitudinal force to thehandle60. In response, thesurface38 of theobturator instrument28 rotates and penetrates soft tissue ST through the incision I. The physician may also gently tap thehandle60, or otherwise apply appropriate additional longitudinal force to thehandle60, to advance theobturator instrument28 through the soft tissue along theguide pin instrument26 down to the entry site (seeFIG. 13). The physician can also tap thehandle60 with an appropriate striking tool to advance thesurface30 of theobturator instrument28 into the side of thevertebral body148 to secure its position (asFIG. 13 shows).
• The physician next slides thehandle60 along theguide pin instrument26 away from theobturator instrument28 to disengage the taperedflange40 from thefirst socket64. The physician then proceeds to slide thehandle60 completely off theguide pin instrument26.
• The physician acquires thecannula instrument30 from thetray126. AsFIG. 14 shows, the physician slides thecannula instrument30 over theguide pin instrument26, distal end first, and, further, over theobturator instrument28, until contact between theend surface48 and soft tissue ST. The physician now slides theguide pin instrument26 andobturator instrument26 through thesecond passage74 andsecond socket66 of thehandle60. The physician slides thehandle60 toward thetapered fitting50 of thecannula instrument30 until a running slip-fit occurs between thesecond socket66 and thetapered fitting50, as previously described. Thecannula instrument30 is now ready for use.
• AsFIG. 14 shows, the physician applies appropriate twisting and longitudinal forces to thehandle60, to rotate and advance thecannula instrument30 through soft tissue ST along theobturator instrument28. AsFIG. 15 shows, when theend surface48 of thecannula instrument30 contacts cortical bone; the physician can appropriately tap thehandle60 with a striking tool to advance the end surface into the side of thevertebral body148 to secure its position.
• AsFIG. 16 shows, the physician now withdraws theobturator instrument28, sliding it off theguide pin instrument26. This leaves theguide pin instrument26 and thecannula instrument30 in place, asFIG. 17 shows. The physician next slides thehandle60 along theguide pin instrument26 away from thecannula instrument30 to disengage the tapered fitting50 from thesecond socket66. The physician then slides thehandle60 completely off theguide pin instrument26.
• The physician now acquires thedrill bit instrument32 from thetray126. AsFIG. 18 shows, the physician slides thedrill bit instrument32 over theguide pin instrument26, distal end-first, through thecannula instrument30 until contact between themachined surface54 and bone tissue occurs. AsFIG. 18 also shows, the physician next leads theguide pin instrument26 through thefirst passage72 andfirst socket64 of thehandle60. The physician slides thehandle60 along theguide pin instrument26 toward the taperedflange56 of thedrill bit instrument32, until a running slip-fit occurs between thefirst socket64 and the taperedflange56, as previously described. Thedrill bit instrument32 is now ready for use.
• As shown byFIG. 18, guided by X-ray (or another external visualizing system), the physician applies appropriate twisting and longitudinal forces to thehandle60, to rotate and advance thecutting edge54 of thedrill bit instrument32 to open a passage166 (seeFIG. 19) through the bone tissue and completely into thecancellous bone152. The drilledpassage166 preferable extends no more than 95% across thevertebral body148.
• The physician now slides thehandle60 along theguide pin instrument26 away from thedrill bit instrument32 to disengage the taperedflange56 from thefirst socket64. The physician, further, slides thehandle60 completely off theguide pin instrument26.
• The physician can now remove thedrill bit instrument32 and theguide pin instrument26, leaving only thecannula instrument30 in place. Thepassage166 made by thedrill bit instrument32 remains. Subcutaneous access to thecancellous bone152 has been accomplished.
• The physician can now acquire the cavity forming instrument from thetray126. AsFIG. 20 shows, the physician can advance theexpandable structure86 through thecannula instrument30 andpassage166 into the interior volume of thevertebral body148, asFIG. 21 also shows. Thestructure86 is in its normally collapsed and not expanded condition during deployment. Thestylet96 or102 is inserted in thelumen94 of thecatheter tube78 to provide added stiffness to thestructure86 while being passed through thecannula instrument30.
• As shown in phantom lines inFIG. 20, the physician can, if desired, reconnect thehandle60 to thecannula instrument30, to help stabilize thecannula instrument30 while deploying thestructure86. Thesecond passage74 of the handle accommodates thecatheter tube78 and thestructure86, when collapsed.
• AsFIG. 21 shows, thestructure86 is oriented in the desired way in thepassage166. As before explained, thebent stylet102 can aid in this task. Before, during, or after the orientation process, thestylet96 or102 can be withdrawn (asFIG. 21 shows), to open thelumen94 for use to pass a rinsing liquid or negative aspiration pressure.
• Sterile liquid is conveyed under pressure from thesource92 through thelumen88 into thestructure86. AsFIG. 22 shows, thestructure86 expands inside bone. Expansion of thestructure86 compressescancellous bone152 in thevertebral body148.
• The compression forms aninterior cavity168 in thecancellous bone152. AsFIG. 23 shows, subsequent collapse and removal of thestructure86 leaves thecavity168 in a condition to receive a filling material.
• The compaction ofcancellous bone152 can also exert interior force upon cortical bone, making it possible to elevate or push broken and compressed bone back to or near its original prefracture, or other desired, condition.
• Upon formation of thecavity168, the physician acquires thesyringe104 andinjection nozzle106 from thekit12. AsFIG. 24 shows, the physician fills thesyringe chamber110 with the desired volume of fillingmaterial170. AsFIG. 25 shows, the physician attaches thenozzle106 to the filledsyringe104. AsFIG. 26 shows, the physician inserts the nozzle106 a selected distance beyond thedistal end36 of thecannula instrument30 and into the cavity, guided by themarkings116.
• As shown in phantom lines inFIG. 26, thehandle60 can remain attached to thecannula instrument30 to provide stability, as thesecond passage74 of the handle accommodates thenozzle106.
• AsFIG. 27 shows, the physician manually advances thepiston112 to cause thematerial170 to flow through and out of thenozzle106 and into the cavity. Asmaterial170 fills the cavity, the physician withdraws the nozzle from the cavity and into thecannula instrument30. Thecannula instrument30 channels thematerial170 flow toward thecavity168. AsFIG. 28 shows, thecement material170 flows in a stream into thecavity168.
• If the selectedmaterial170 is bone cement, thecement material170 is placed into thesyringe chamber110 shortly after it is mixed from two materials (e.g., in an external mixing device), while it is in a low viscosity, relatively free flowing liquid state, like a thin pancake batter. In time (e.g., about two minutes after mixing), the consistency of thecement material170 will change to a substantially putty-like character.
• The physician operates thesyringe104 to expel thecement material170 from the chamber, through thenozzle106, first into the cavity and then into thecannula instrument30. Typically, at the end of the syringe injection process,material170 should extend from the cavity and, occupy about 40% to 50% of thecannula instrument30.
• When a desired volume of cement is expelled from thesyringe104, the physician withdraws thenozzle106 from thecannula instrument30, asFIG. 29 shows. The physician may first rotate thesyringe104 andnozzle106, to break loose the material170 in thenozzle106 from the ejected bolus ofmaterial170 occupying thecannula instrument30.
• The physician acquires the tampinginstrument108 from thekit12. AsFIG. 30 shows, the physician advances the tampinginstrument108 through thecannula instrument30. As phantom lines inFIG. 30 show, thehandle60 can remain attached to thecannula instrument30 to provide stability, as thesecond passage74 of the handle accommodates the tampinginstrument108.
• The distal end of the tampinginstrument108 contacts the residual volume ofcement material170 in thecannula instrument30. AsFIGS. 30 and 31 show, advancement of the tampinginstrument108 displaces progressively more of theresidual material170 from thecannula instrument30, forcing it into thecavity168. The flow ofmaterial170 into thecavity168, propelled by the advancement of the tampinginstrument108 in thecannula instrument30, serves to uniformly distribute and compact thematerial170 inside thecavity168, without the application of undue pressure.
• The use of thesyringe104,nozzle106, and the tampinginstrument108 allows the physician to exert precise control when filling the cavity withmaterial170. The physician can immediately adjust the volume and rate of delivery according to the particulcar local physiological conditions encountered. The application of low pressure (i.e., no greater than 360 psi), which is uniformly applied by thesyringe104 and the tampinginstrument108, allows the physician to respond to fill volume and flow resistance conditions in a virtually instantaneous fashion. The chance of overfilling and leakage ofmaterial170 outside the cavity is significantly reduced.
• When the physician is satisfied that thematerial170 has been amply distributed inside thecavity168, the physician withdraws the tampinginstrument108 from thecannula instrument30. The physician preferably first twists the tampinginstrument108 to cleanly break contact with thematerial170. Thehandle60 can now be removed and thecannula instrument30 withdrawn, asFIG. 32 shows. The incision site is sutured closed. The bone treatment procedure is concluded.
• Eventually thematerial170, if cement, will harden a rigid state within thecavity168. The capability of thevertebral body148 to withstand loads is thereby improved.
• The selectedmaterial170 can be an autograft or allograft bone graft tissue collected in conventional ways. For example, the graft material can be in paste form, as described by Dick, AUse of the Acetabular Reamer to Harvest Autogenic Bone Graft Material: A Simple Method for Producing Bone Paste,@ Archives of Orthopaedic and Traumatic Surgery (1986), 105: 235-238, or in pellet form; as described by Bhan et al, A ercutaneous Bone Grafting for Nonunion and Delayed Union of Fractures of the Tibial Shaft,@ International Orthopaedics (SICOT) (1993) 17: 310-312, both of which are incorporated herein by reference. Alternatively, the bone graft tissue can be obtained using a Bone Graft Harvester, which is commercially available from SpineTech. Using a funnel, the paste or pellet graft tissue material is loaded into thecannula instrument30. The tampinginstrument108 is then advanced into thecannula instrument30 in the manner previously described, to displace the paste or pellet graft tissue material out of thecannula instrument30 and into the cavity.
• The selectedmaterial170 can also comprise a granular bone material harvested from coral, e.g., ProOsteonJ calcium carbonate granules, available from Interpore. The granules are loaded into thecannula instrument30 using a funnel and advanced into the cavity using the tampinginstrument108.
• The selectedmaterial170 can also comprise demineralized bone matrix suspended in glycerol (e.g., GraftonJ allograft material available from Osteotech), or SRSJ calcium phosphate cement available from Novian. These viscous materials, like the bone cement previously described, can be loaded into thesyringe104 and injected into the cavity using thenozzle106, which is inserted through thecannula instrument30 into the cavity. The tampinginstrument108 is used to displace residual material from thecannula instrument30 into the cavity, as before described.
• The selectedmaterial170 can also be in sheet form, e.g. CollagraftJ material made from calcium carbonate powder and collagen from bovine bone. The sheet can be rolled into a tube and loaded by hand into thecannula instrument30. The tampinginstrument108 is then advanced through the cannula instrument, to push and compact the material in the cavity.
VI. Alternative Embodiments
• The use of low pressure delivery ofmaterial170 frees thesystem10 from the need to accommodate relatively large diameter, high pressure delivery devices. The interior diameter of thecannula instrument30 can be downsized accordingly, thereby minimizing the dimensions of the subcutaneous pathway to gain access to the targeted bone region.
• Typically, when low pressure material injection instruments are used, the largest tool that the reduced-diameter cannula instrument must accommodate is the expandable cavity-formingstructure82. Thestructure82 presents a minimal profile during deployment, as it can be collapsed and, if desired, a lubricous coating may also be applied to the exterior of thestructure82 to facilitate its passage through the reduced-diameter cannula instrument.
• A. Low Pressure Material Injection Instruments
• FIG. 33 exemplifies low pressurematerial injection instruments180 and182 that function in association with acannula instrument184 having a reduced interior diameter, e.g. only about 3.4 mm or less.
• Oneinstrument180 comprises a reduced-diameter nozzle. AsFIG. 33 shows, thenozzle180 is sized to pass through the reduced-diameter cannula instrument184, to thereby pass into bone in the manner previously shown inFIG. 26. The reduced-diameter nozzle180 connects by a threadedconnector186 to thesyringe104. For material strength, despite its reduced dimension, thenozzle180 is preferably formed from a rigid metal material, e.g., stainless steel.
• AsFIG. 33 shows, the reduced-diameter nozzle180 also includes measuredmarkings188 along its length, as previously described. Themarkings188 include aset point190, as previously described, which aligns with the proximal end of thecannula instrument184 when the distal ends of thecannula instrument184 and thenozzle180 align.
• The other reduced diameter,instrument182 comprises a stylet, which is sized to pass through the interior bore of thenozzle180. Thestylet182 includes ahandle192, which rests on theproximal connector186 of thenozzle180 when thestylet182 is fully inserted into thenozzle180. When thehandle192 is rested, the distal ends of thestylet182 andnozzle180 align. The presence of thestylet182 inside thenozzle180 closes the interior nozzle bore.
• In use, thenozzle180 is coupled to thesyringe104 and inserted through thecannula instrument184 into the material-receivingcavity168 formed in cancellous bone, in the same manner shown inFIG. 26. Material in thesyringe104 is injected at low pressure through thenozzle180 into thecavity168. As before explained, as thecavity168 progressively fills with material, thenozzle180 is withdrawn back into thecannula instrument184. Typically, when the injection of material is completed, material extends from thecavity168 and occupies about 40% to 50% of thecannula instrument184.
• At this point, thenozzle180 can be fully withdrawn from thecannula instrument184 and unthreaded from thesyringe104. Thestylet182 can be advanced into thenozzle180, to bring thehandle192 at rest against theconnector186, thereby clearing residual material from thenozzle180. Thenozzle180 and stylet can then be inserted as a nested unit into thecannula instrument184. Nested together, thenozzle180 andstylet182 form a tamping instrument. Upon advancement through thecannula instrument184, the nestednozzle180 andstylet182 displace residual material from thecannula instrument184 into thecavity168, in generally the same manner as previously shown inFIGS. 30 and 31, thereby uniformly compacting material within thecavity168 in a controlled fashion and without undue pressure.
• Alternatively, a single-piece tamping instrument, separate from thenozzle180, can be provided, downsized to fit through the reduced-diameter cannula instrument184. In this embodiment, thestylet182 is not necessary, unless it is desired to reclaim material from the nozzle.
• B. Cavity Forming Instrument
• FIG. 34 shows acavity forming instrument194 intended to be deployed through the reduced-diameter cannula instrument184, shown inFIG. 33. In many respects, theinstrument194 is like theinstrument76, previously described and shown inFIG. 4A, and common reference numerals will be assigned to common structural elements. Theinstrument184 includes aflexible catheter tube78 having aproximal end80 and adistal end82. Theproximal end80 carries ahandle grip84, and thedistal end82 carries anexpandable structure86, which, when deployed in bone, compacts cancellous bone and forms thecavity168.
• Unlike the previously-describedinstrument76, theinstrument194 carries anintroducer sleeve196. Theintroducer sleeve196 slides along thecatheter tube78 between thehandle grip84 and theexpandable structure86. Theintroducer sleeve196 includes a tubularmain body198 with aforward collar200 and arear collar202.
• Theintroducer sleeve196 normally occupies an advanced position on theinstrument194, as shown inFIG. 35. In this position, themain body198 overlies and surrounds theexpandable structure86. Themain body198 is sized to compress thestructure86 to an outside diameter that is slightly less than the interior diameter of the reduced-diameter cannula instrument184.
• AsFIG. 35 shows, when theintroducer sleeve196 occupies the advanced position, theforward collar200 extends beyond the distal end of the compressedexpandable structure82. AsFIG. 36 shows, in this position, theforward collar200 presents itself for engagement with theproximal end204 of thecannula instrument184. Theforward collar200 is sized to have an interior diameter that makes friction-fit engagement about theproximal end204 of thecannula instrument184.
• AsFIG. 36 shows, when it is time to deploy theexpandable structure86 through thecannula instrument184, the physician engages theforward collar200 of theintroducer sleeve196 in a friction fit about theproximal end204 of thecannula instrument184. AsFIG. 37 shows, advancing thecatheter tube78 moves thecompressed structure86 through themain body198 of thesleeve196 and into the bore of thecannula instrument184. The engagement of theforward collar200 about theproximal cannula end204 aligns the axis of thestructure86 with the axis of thecannula instrument184, while compressing thestructure86 to a diameter smaller than the interior of thecannula instrument184. Upon advancement of thecatheter tube78, theintroducer sleeve196 guides thestructure86 into thecannula instrument194 without tearing or other damage.
• Once theexpandable structure86 is advanced through thecannula instrument184 and into bone, the physician can slide theintroducer sleeve196 rearward away from the proximal cannula,end204, to break the friction fit between theend204 and the forward sleeve. AsFIG. 34 shows, therear collar202 of thesleeve196 is sized to make a snap fit engagement about astem206, which surrounds thecatheter tube78 near thehandle84.
• The snap fit engagement stabilizes the position of thesleeve196 during subsequent use and manipulation of the cavity-forminginstrument194.
• The features of the invention are set forth in the following claims.

Claims (11)

1. 22. A kit comprising:

   an access tool sized and configured to provide an access path through soft tissue to bone having an exterior formed, at least in part, by cortical bone, and an interior volume occupied, at least in part, by cancellous bone;

   an elongate tool sized and configured to fit within the access path, and create a passage in the cancellous bone; and

   a void forming tool sized and configured to be introduced through the access path and into the passage to form a void in cancellous bone.
2. 23. The kit ofclaim 22, wherein the access tool comprises a cannula.
3. 24. The kit ofclaim 22, wherein the elongate tool comprises an obturator.
4. 25. The kit ofclaim 22, wherein the elongate tool comprises a drill.
5. 26. The kit ofclaim 22, wherein the void forming tool is carried by an elongate member sized and configured to pass through the access path.
6. 27. The kit ofclaim 26, wherein the void forming tool comprises an expandable body.
7. 28. The kit ofclaim 27, wherein the expandable body, when expanded, assumes a non-spherical shape.
8. 29. The kit ofclaim 27, wherein the elongate member comprises:

   a first catheter defining a first lumen for delivering an inflation fluid to the expandable body; and

   a second catheter positioned at least partially within the first lumen.
9. 30. The kit ofclaim 29, wherein the expandable body possesses a preformed hour-glass or peanut shape.
10. 31. The kit ofclaim 26, further comprising an inflation source for delivering inflation fluid to the expandable body.
11. 32. The kit ofclaim 22, further comprising a nozzle sized and configured to be introduced through the access path and deliver filling material to the void.

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