US20010034526A1 - Expandable reamer - Google Patents

Abstract

An expandable reamer for forming a space within a vertebral disc includes a pair of opposing blades which have a expanded state and a retracted state. The blades being pivotally positioned at the distal end of a shaft assembly. A shaft housing being substantially disposed about the shaft assembly. The proximal end of the shaft assembly being operatively engaged by a control device which when rotated allows the blades to be fully retracted for insertion into a pre-bored hole and then to be expanded incrementally until the cavity is bored as desired.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The present Utility Patent Application claims priority to Provisional Application No. 60/182,610 filed Feb. 15, 2000, the entire contents of which being incorporated herein by reference.[0001]
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
• Not Applicable[0002]
BACKGROUND OF THE INVENTION
• 1. Field of the Invention[0003]
• This invention relates to an expandable reamer for use in surgery, particularly in orthopedic applications.[0004]
• 2. Description of the Related Art[0005]
• U.S. Pat. No. 5,445,639 to Kuslich et al., describes an intervertebral reamer which is used to ream out the interior of a degenerated disc to clean the interbody space. U.S. Pat. Nos. 5,549,679 and 5,571,189 to Kuslich describes a device and method for stabilizing the spinal segment with an expandable, porous fabric implant for insertion into the interior of a reamed out disc which is packed with material to facilitate bony fusion.[0006]
• U.S. Pat. No. 5,928,239 to Mirza discloses a reamer which has a shaft and a cutting tip attached through a free rotating hinge such that high speed rotation allows the tip to be deflected outwardly to form a cavity. U.S. Pat. No. 5,591,170 to Spievack et al discloses a powered bone saw which inserts its cutting blade through a bored intramedullary canal.[0007]
• The reamer of U.S. Pat. No. 5,445,639 is better suited to make a cylindrical bore than a spherical bore as is needed for the methods and apparatus of U.S. Pat. Nos. 5,549,679 and 5,571,189, the disclosure of all of which are incorporated herein by reference. There exists, therefore, a need for an instrument which will simplify the surgeon's task of forming a chamber within the interbody space.[0008]
• The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. § 1.56(a) exists.[0009]
SUMMARY OF THE INVENTION
• The invention provides a surgical tool is for forming hollow chambers within bone that are larger in diameter than the external opening into the chamber. The tool has a distal end with external dimensions sized to be passed through the patient's anatomy to a point of entry into the bone. Retractable cutting blades are provided on the cutting end. The blades can be extended to cut a cavity greater than the diameter of the surgical tool.[0010]
BRIEF DESCRIPTION OF THE DRAWINGS
• A detailed description of the invention is hereafter described with specific reference being made to the drawings in which:[0011]
• FIG. 1 is a perspective view of the reamer of the invention wherein the blades of the reamer are shown in the retracted position;[0012]
• FIG. 2 is an exploded view of the reamer of FIG. 1;[0013]
• FIG. 3 is top down view of an embodiment of the blade advancer arbor portion of the reamer of FIG. 1;[0014]
• FIG. 4 is an exploded view of an embodiment of the blade advancer arbor;[0015]
• FIG. 5 is a side view of the blade assembly portion of the reamer of FIG. 1, wherein the blades are shown in the retracted position;[0016]
• FIG. 6 is a side view of the blade assembly portion of the reamer of FIG. 1, wherein the blades are shown in the retracted position;[0017]
• FIG. 7 is an exploded view of an embodiment of the blade assembly and guides;[0018]
• FIG. 8 is an enlarged view of a portion of the distal end of the blade assembly with a blade in the retracted position;[0019]
• FIG. 9 is an enlarged view of a portion of the distal end of the blade assembly with a blade extended;[0020]
• FIG. 10 is a perspective view of an alternative embodiment of the reamer;[0021]
• FIG. 11 is an exploded view of the reamer of FIG. 10;[0022]
• FIG. 12 is a close up view of threaded portion and end of the shaft shown in FIG. 11;[0023]
• FIG. 13 is a view depicting the assembly of the barrel and turn wheel of the reamer shown in FIG. 11;[0024]
• FIG. 14 is a side view of an alternative embodiment of the blade assembly wherein the blades are retracted;[0025]
• FIG. 15 is a side view of the blade assembly shown in FIG. 14 wherein the blades are extended;[0026]
• FIG. 16 is an enlarged view of a portion of the distal end of the blade assembly of FIG. 14 with a blade in the retracted position; and[0027]
• FIG. 17 is an enlarged view of a portion of the distal end of the blade assembly of FIG. 14 with a blade extended.[0028]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Reference is now directed to FIGS. 1 through 17 in which identical elements are numbered identically throughout.[0029]
• In FIGS. 1 and 2 an embodiment of the inventive reamer, indicated generally by[0030]reference numeral132, is shown. Thereamer132 includes ahandle134, ablade advancing arbor138 and amain shaft136. Within the main shaft is anelongate shaft140 which may extends distally beyond the distal end of themain shaft136. As may be seen, theelongated shaft140 includes ablade advancing tab148 at the proximal end and a pair ofblades142,144 hingedly mounted to the distal end by ahinge pin146.
• As may best be seen in FIG. 2,[0031]main shaft136 is hollow to allow it to carry theelongated shaft140 and theblade guides150 and152. Theblade guides150 and152 each have a relatively slender shaft154 aproximal tab156 and anarcuate guide slot158 at their distal ends. Theelongated shaft140 is positioned between theblade guides150 and152.
• The diameter of[0032]shaft136 atdistal end172 is sized such thatshaft136 can be inserted into a patient's body withdistal end172 placed against a diseased disc or other bone withoutshaft136 having undue interference with other anatomical organs.
• FIG. 4 shows that[0033]main shaft136 is attached to aguide member182 which defines aguide tab slot184 for engaging theguide tabs156. Theblade advancing tab148 and the assocaiatedshaft140 longitudinally moveable therebetween. The end of theguide member182 includes a threadedshaft190 which is received into an opening192 inblade advancer knob194. Theguide member182 is inserted into an opening inblade advancer barrel138.Blade advancer barrel138 includes anannular recess200 to mate withknob lip202 which rotatably secures theknob194 to thebarrel138. Thebarrel138 may include ashaped opening204 designed to engage shapedmember206 on theguide member182.
• In the embodiment shown, the[0034]guide member182 is inserted intoopening204 with theelongated blade shaft140 and theblade advancing tab148 as well as blade guides156 fully inserted intoslot184. Theblade advancing tab148 projects above theguide member182 such that agroove210 may be provided in theblade advancer barrel138 to allow the assembly to pass therewithin.
• The[0035]guide member182 may include apin212 which passes from theguide member182 across the barrel opening216 to engage the pin opening232 of theslide door214. When properly assembled thetab148 protrudes through the tab opening230 of thedoor214 such as may be seen in FIG. 3. This mutually engaging relationship keeps theelongated blade shaft140 from moving.
• After the[0036]guide member182 is inserted fully into thebarrel138, theslide door214 is placed ontoblade advancer barrel138 to close theaccess opening216. The slide door may be held at the proximal end by engagement of itstabs220 toslots222 in the barrel. The distal end of thedoor214 is held in position by alock ring224 that engages withthreads226 or the like on the distal end ofbarrel138 as is shown in FIG. 4.
• As stated above, the[0037]slide door214 includes a pair ofopenings230,232.Opening230 engages withtab148 to keep theelongated shaft140 from moving. Observation of the position of thepin212 within the confines of opening232 allows a user to track the degree of movement that theshaft136 makes longitudinally in response to turningknob194.
• As may best be seen in FIG. 4, when[0038]knob194 is turned or rotated, theshaft136 is moved inwardly or outwardly withinbarrel138. The movement of theshaft138 is relative to theelongate shaft140 which is held stationary by theblade advancing tab148 withinshaft138. This functional relationship causes theblades142 and144 to pivotally retract or expand relative toshaft136, such as may be seen in FIGS. 5 and 6. However, movement ofknob194 actually causes theentire shaft136, together with blade guides150 and152, which forces the blades to move as theirengagement members160 move withinarcuate guide slots158 of the blade guides.
• As may best be seen in FIG. 7, the[0039]blades142,144 each include anengagement member160 which aligns witharcuate guide slot158, defined by thediverter housings166 and168 respectively. When theengagement members160 are fully withinarcuate guide slots158, the blades are extended out their maximum extent for cutting withblade portions162, such as may best be seen in FIG. 9. As theengagement members160 are withdrawn from theguide slots158, such as may be seen in FIG. 8, theblades142 and144 are retracted for insertion and/or withdrawal from the patient.
• Turning to FIGS.[0040]10-17, an alternative embodiment of the invention is shown. FIGS.10-17 are directed to a more compact form of the reamer of the present invention. As depicted herein, the diameter of thereamer90 with closed blades, such as may best be seen in FIG. 14 may have a diameter of approximately 5 mm or less. Thepresent reamer90 may be used to create openings through pedicles, channels for anterior cruciate ligaments and the like. Rather, an elongated tube andbarrel100 carry along rod92 that attaches at the proximal end to aturn wheel96 that moves the blades distally and proximally. The end of thelong rod92 is attached to two like blades by apivot118 that allows theblades114 and116 to change position. Each of theblades114 and116 have asloping lever side120 that allows them to move smoothly outwardly. A notch or stop126 bottoms out against themain tube100 to prevent further movement. The handle may have aflat slot107 milled therein that allows the user to see whether therod92 is in position for cutting or pushed forward for no cutting. Asecond slot106 provides an access space sufficient to allow a user to remove the retainingclip108, so that the reamer may be disassembled as discussed below.
• Note that if the[0041]blades114 and116 were ever stuck in an open position, thehandle96 could be removed, allowing the tube to be removed and then theblades114 and116 would have nothing to keep them open. This blade setup allows disassembly if the blades are stuck open in the bone. Prior reamer designs may be difficult to disengage in such an event. In this design, the entire device may be disassembled from the proximal end such that the parts are released allowing theblades114 and116 to pivot freely. In the embodiment shown in FIG. 11, removal of the retainingclip108 will allow theturn wheel96 to be separated from thebarrel102. Thebarrel102 along with theshaft housing104 may then be slid off of theelongate shaft92. When theshaft92 is no longer retained by thehousing104, theblades114 and116 will be free to move into the retracted position by merely pulling theshaft92 from the bone or operation site (not shown).
• As shown in FIGS.[0042]10-14,reamer90 is elegantly simple. It includes anelongated shaft92 with aproximal tab129 which may include a threadedproximal end94 which may receive thetab129 viaslot128. The combined threadedproximal end94 andelongate shaft92 is engaged with theturn wheel96 thereby providing a theshaft92 with the ability to be moved up and down withinholder100 as thewheel96 is turned.
• The[0043]holder100 includes anenlarged barrel102 into which theturn wheel96 may partially descend and a lower hollowcylindrical guide104. Thedistal end110 ofshaft92 includes anarrow tang111 which has an opening therethrough to allowblades114,116 to be hingedly attached via ahinge pin member118.
• As best shown in FIGS. 14 and 15, the[0044]blades114,116 include aramp portion120 sized to entercylindrical tube104 and a cuttingportion122. As may be seen in FIGS.14-17, the cuttingportion122 of theblades114 and116 may be serrated. When turn wheel96 is turned to pull theshaft92 up into thecylindrical tube104, the rampedportion120 enters thetube104 and begins to extend theblade portion122 out past the diameter of thetang111. As shown in FIG. 15,blades114,116 are at their most extended portion as limited by astop member126 which abuts against thecylindrical tube104 preventing further extension.
• [0045]Turn wheel96 may includedepth marking slot107 which allows the user to see how far the blades have extended or retracted. In addition, the portion of theshaft92 which may be seen through theslot107 may have visible markings or surface features to better provide a visual basis for determining the extent of the blade retraction or extension based on the relative position of theshaft92 within theslot107. In the unlikely event that thereamer blades114,116 cannot be readily retracted within the cavity being formed, theturn wheel96 may be removed, allowing theholder100 to slide away from theshaft92. In such a case, theblades114,116 would freely pivot onhinge pin118 allowing the remainder of thereamer90 to be readily removed.
• FIGS.[0046]11-13 show the construction of thebarrel102 and the interface of theturn wheel96 to thereamer90.Turn wheel96 includes aprojection member97, which may be a threaded nut or screw which is inserted into theturn wheel96 and threadingly engaged to aretaining clip108. The retainingclip108 is fittingly or frictionally engaged to a retainingslot109 positioned about the proximal end of thebarrel102, the position of the retainingslot109 corresponds to the position of theindentation98 ofmember97 whenmember97 is threadingly engaged to threadedproximal end94. Theslot109 has a diameter less than the diameter of thesurrounding barrel102.Barrel102 includes a bore which communicates through thecylindrical tube104.
• As may be best understood from viewing FIG. 11, in order for the[0047]turn wheel96 to be properly engaged to the barrel102 a variety of components must initially be assembled with in thewheel96. A projectingmember97 is inserted through theturn wheel96. Disposed about theprojection member97 is a biasing member such as acoiled spring95. Thespring95 is pushed into thewheel96 along with themember97. A retainingring93 is fittingly engaged into thewheel96 to retain themember97 andspring95 therein.
• As may best be seen in FIG. 13, at the proximal end of the[0048]barrel102, anopening124 is formed which conforms to the cross-sectional shape of the threadedend94 andtab129. Theindentation98 of theprojection member97 engages the retainingclip108 such that when threadedend128 is threaded intoopening130 or theturn wheel96, theturn wheel96 cannot be removed fromshaft92 without unscrewing theshaft92 from opening130 and removinglock pin108.
• In one embodiment of the invention, when the[0049]turn wheel96 is assembled in the manner described above, the spring95 (shown in FIG. 11) is biased betweenshoulder99 ofmember98 andshoulder135 of theturn wheel96. This biasing relationship provides sufficient tension force to between themember98 and thewheel96 to prevent unintentional movement of the turn wheel relative to thebarrel102. In order to rotate thewheel96, thewheel96 must be pulled longitudinally away from thebarrel102 with sufficient force to overcome the biasing force of thespring95. When pulled in this manner the wheel may be freely rotated.
• In an alternative embodiment of the invention, the turn wheel includes a plurality of engagement pins[0050]131. Each engagement pins131 is engaged to receivingholes133. In order to rotate thewheel96 thewheel96 is pulled in the manner described above, but additionally must be pulled a sufficient distance away from thebarrel102 to disengage thepins131 from theholes133. Thewheel96 may then be rotated to a point where thepins131 may be reinserted into theholes133 in an advancing clockwise or counter-clockwise manner.
• When the[0051]reamer90 is assembled in the manner described above, clockwise rotation of theturn wheel96causes shaft92 to be pulled uptube104 such thatramp portion120, such as may be seen in FIGS.14-17, enterstube104 causing theblades114,116 to extend outwardly until thestop126 abuts with the distal end oftube104.
• As shown in FIG. 14-[0052]17,blades114 and116 include a cutting edges122. In the embodiment shown, the cuttingedges122 may be serrated, however straight, orcurved cutting edges122 may also be provided. In the various embodiments described herein, the blades of the inventive reamer may be constructed from a variety of materials such as metal, composite materials such as carbon etc. Where the blades are metal, the metal may be any type of metal suitable for use in constructing a blade for use in medical procedures. Such metals may include: stainless steel, spring steel, titanium, nickel, or any alloys thereof.
• As may be seen in FIG. 14, the blades[0053]116 (114 is not shown) are shown in a mostly retracted position, whereas in FIG. 15 theblades114 and116 are depicted in a fully extended position. Any position between a fully retracted and fully extended position is possible with thereamer tool90 of the invention.
• In operation, the[0054]blades114 and116 are fully retracted and thedevice90 is inserted into an opening drilled into the body material where a cavity is to be formed. Typically a hole is drilled into the vertebral body or other bone or area that needs to be reamed to a diameter larger than the outside drill hole. The hole is drilled in the bone, and then a guide tube may be abutted against the bone and adjusted to the proper length or depth where it is desired to ream the hole. Thereamer90 is then inserted through the optional guide tube with theblades114 and116 in the retracted position, such as is shown in FIG. 14. Once inserted into the bone to a desired depth, theturn wheel96 is rotated to begin expansion of theblades114 and116. Rotation of thereamer92 with theblades114 and116 gradually expanding, provides a cutting action which reams out a chamber from within the bone.
• In use, turning or rotating the[0055]turn wheel96 relative to thebarrel102 causes theshaft92 to be moved longitudinally relative to theshaft housing104. This action causes theblades114 and116 to pivot around thepivot member118 thereby expanding out from or retracting into thetapered ramps119, as seen in FIGS. 16 and 17, depending on the direction of the turn wheel's rotation. As theblades114 and116 are rotated out of theramps119 theentire reamer92 may be rotated causing theblades114 and116 to cut an expanding hole in the cavity, which is limited in size to the maximum expanded state of theblades114 and116, such as is shown in FIG. 15.
• Once a reamed cavity is made, the[0056]blades114 and116 are retracted by rotating theturn wheel96 in a direction opposite that which was used to expand the blades, until theblades114 and116 are fully retracted. However, it should be noted that unlike in the embodiment shown in FIGS.1-9, the present embodiment does not rely on the ramps or slots to retract the blades. Instead, theblades114 and116 may be free to retract when pulled from the hole. Thus when thereamer90 is withdrawn from the hole theblades114 and116 may retract by themselves as a result of engagement with the drill hole shaft or the guide tube.
• The surgeon may visualize the degree the[0057]blades114 and116 extend by viewing the position of theshaft92 relative to thebarrel102, throughview port107. Theshaft92 may have markings or surface features to make such position determinations easier. In the embodiment shown, the surgeon can see how far down theshaft92 moves as theturning wheel96 is rotated. Thereamer90 may be calibrated to show the distance the blades project from the tool.
• While this invention may be embodied in many different forms, there are shown in the drawings and described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.[0058]
• This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.[0059]

Claims (14)

What is claimed is:

1. An expandable reamer comprising:

a) an elongated hollow shaft having a proximal and a distal end, the distal end being closed and having a pair of opposing side openings adjacent the closed end;

b) a pair of internal blade members within said hollow shaft;

c) a mechanism for moving said blades from a retracted position within the shaft to a cutting, extended position through said side openings.

2. The expandable reamer of

claim 1

wherein said distal closed end includes an inner, centrally located wedge constructed and arranged to direct the internal blade members out of said side openings when pressed distally.

3. The expandable reamer of

claim 2

wherein said internal blade members each include an elongated shaft having a distal and a proximal end, said proximal end extending up to said blade moving mechanism and a cutting blade on a distal end of said elongated shaft which are completely within said hollow shaft until said elongated shafts are urged distally by said blade moving mechanism.

4. The expandable reamer of

claim 3

wherein said blade moving mechanism is constructed and arranged to engage said proximal end of said blade member elongated shaft and simultaneously move both blades distally or proximally in response to operator movement of said blade moving mechanism.

5. The expandable reamer of

claim 4

wherein said blade moving mechanism includes an adjusting screw which when rotated causes said blades to move distally or proximally in said elongated hollow tube in response to the direction of rotation and degree of rotation.

6. The expandable reamer of

claim 5

further including an indicator mechanism toward the proximal end of said reamer which is visible from the outside of said reamer and shows relative movement of said blades proximally and distally within said hollow shaft to indicate position of the cutting blades.

7. The expandable reamer of

claim 6

wherein said reamer includes a mechanism for applying rotational torque to said hollow shaft such that said cutting blades rotate and provide a cutting operation.

8. The expandable reamer of

claim 7

wherein said cutting blades are constructed and arranged to fully retract within said hollow shaft until said blade moving mechanism urges them out said side openings such that said cutting blades are not in a cutting position until desired.

9. The expandable reamer of

claim 8

wherein said elongated shafts of said blade members are rectangular in cross-section and abut against each other within said hollow shaft to increase torsional rigidity.

10. The expandable reamer of

claim 9

wherein the proximal ends of said elongated shafts of said blade members include notches which engage with an adjustment slide of said blade moving mechanism.

11. The expandable reamer of

claim 10

wherein said adjustment slide is inserted through a side access port which is covered by a locking cover.

12. The expandable reamer of

claim 11

wherein said blade members are spring steel and constructed and arranged to have a slip fit within the hollow shaft such that the blade members may be inserted into said hollow shaft through said side openings while limiting movement of said blade members within said shaft.

13. An expandable reamer comprising:

a) an elongated shaft having a proximal end and a distal end, a pair of blade members pivotally engaged to the distal end of the elongated shaft, a pair of elongated blade guides positioned immediately adjacent to the elongate shaft, the elongate blade guides each having a guide slot, at least a portion of each of the pair of blade members being operatively engaged to one of the guide slots;

b) an elongate hollow tube, the elongate hollow tube being disposed substantially about the elongated shaft and the pair of elongated blade guides, the elongate hollow tube being longitudinally moveable relative to the elongated shaft;

c) a handle, the handle having a hollow engagement barrel and at least one griping member extending therefrom, the hollow engagement barrel having a first end engaged to the elongate hollow tube, and a second end having a control knob, the control knob being operatively engaged to the elongate hollow tube, whereby when the control knob is rotated the elongate hollow tube is moved longitudinally relative to the elongated shaft causing the pair of blade members to move between a retracted position and an extended position.

14. An expandable reamer comprising:

a) an elongated shaft having a proximal end and a distal end, a pair of blade members being pivotally engaged to the distal end of the elongated shaft, the distal end of the elongate shaft having a pair of blade slots constructed and arranged to slidingly and removably receive at least a portion of one of the blade members:

b) an elongate hollow tube, the elongate hollow tube being disposed substantially about the elongated shaft, the elongated shaft being longitudinally moveable relative to the elongate hollow tube;

c) a turn wheel, the turn wheel operatively engaged to the proximal end of the elongated shaft and positioned proximal to the elongate hollow tube, whereby when the turn wheel is rotated the elongated shaft is moved longitudinally relative to the elongate hollow tube causing the pair of blade members to move between a retracted position and an extended position.

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