WO2011014677A1

WO2011014677A1 - Instrument for creating microfractures in a bone

Info

Publication number: WO2011014677A1
Application number: PCT/US2010/043746
Authority: WO
Inventors: David Leo Bombard; Brian J. White
Original assignee: Mtmed I, Llc
Priority date: 2009-07-30
Filing date: 2010-07-29
Publication date: 2011-02-03
Also published as: AU2010278867A1; CN102781346A; EP2459082A1; EP2459082A4; CN102781346B; JP5815522B2; JP2013500786A; AU2010278867B2

Abstract

An instrument to create microfractures in subchondral bone without skiving and a method of using the same are provided. The instrument includes an outer sleeve having a handle coupled to a hollow tube, wherein the end of the tube is curved and includes features to secure the end on a subchondral bone. A puncture element is provided and designed to be inserted through the outer sleeve and translate and/or rotate therethrough into the subchondral bone when directed. The end of the puncture element having a surface that allows the tip to penetrate into the bone to provide a microfracture therethrough without the instrument skiving across the subchondral bone.

Description

INSTRUMENT FOR CREATING

MICROFRACTURES IN A BONE

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

[0001] The present invention is directed to an instrument for repairing cartilage defects and, more particularly, to an instrument for performing microfracture on subchondral bone to repair cartilage.

RELATED ART

[0002] Injuries and defects to articular cartilage are frequent and can cause severe stress and strain to joints. Typically, articular cartilage is unable to repair or heal itself, and if left untreated, can progress to osteoarthritis. Microfracture is treatment commonly used to treat articular defects and injuries. Microfracturing includes penetrating the subchondral bone to induce fibrin clot formation and the migration of primitive stem cells from the bone marrow into the defective cartilage location. As described in U.S. Patent 6,960,214, the base of the defective area is shaved or scraped to induce bleeding and a microfracture instrument is then used to make small holes or microfractures in the subchondral bone plate. In some procedures, the end of the instrument is manually struck with a mallet or other such instrument. The instrument penetrates a vascularisation zone creating 2-3 mm diameter holes which penetrate to a depth of 3-4 mm in the subchondral bone plate on the articular bone surface. This then will form a clot on the prepared bed of bone, which will regenerate to form cartilage.

[0003] A disadvantage with known microfracture instruments is the angle at which the instrument addresses the subchondral bone. Specifically, if the microfracture instrument is not directed perpendicular to the bony surface, the instrument may skive or skip across the bony surface when struck with the mallet or pneumatic tool. This can cause complications with the microfracture procedure and result in an inferior clot formation and cartilage re-growth. With hip arthroscopy, it is very difficult to achieve this perpendicular orientation of the current instrumentation to the bony surface because of the depth of the joint, the limited space between the femoral head and the acetabulum, and the orientation of the portal to the bony surface. Even though current instrumentation may be curved at its tip, the necessary force is not applied perpendicularly to the bony surface. In addition, most full thickness cartilage lesions involve the superolateral aspect of the acetabular bone. This area is very difficult to microfracture with currently available instruments, as it is virtually impossible to direct a force generally perpendicular to the subchondral bone with existing microfracture picks. This is also true for microfracture of the patella, talus, coronoid process, and other parts of the knee and shoulder.

[0004] The propensity for the instrument to skive across the bony surface is further compounded by the force of striking the instrument. Other problems with instruments of the prior art are that they tend to work by drilling and such action tends to cause degradation of the tissues; further the use of these instruments is heat generating and therefore thermal damage also often occurs. Accordingly, it would be desirable to have an instrument that facilitates a generally perpendicular orientation to the bony surface for the microfracture technique during arthroscopy of the hip and other joints, as well as, enables and directs the force of the puncture element generally perpendicularly to the bony surface. It would also be desirable for the instrument to rotate and drill, with a self-tapping drill bit or screw tip with a relatively low friction, into the subchondral bone, facilitating the lower speed change in direction of the puncturing force. Such a design would reduce the skive force seen with traditional microfracture picks.

SUMMARY OF THE INVENTION

[0005] In accordance with one embodiment of the present invention, a microfracture instrument is provided that includes a guide which can comprise an outer sleeve and a puncture element extending through the outer sleeve. The outer sleeve includes a handle coupled to a hollow tube, wherein the end of the tube is curved and includes features to secure the end on a subchondral bone. The puncture element is designed to be housed in the outer sleeve and translate and/or rotate therethrough into the subchondral bone. The puncture element has a flexible end portion with a tip on the flexible end portion that allows the tip to penetrate into the bone to provide a microfracture therethrough. The puncture element can be permanently coupled to the sleeve. The puncture element can be removably attached to the sleeve in whole or in part. The flexible end portion having the tip thereon can be interchangeable or the tip alone can be interchangeable. In one embodiment the tip of the flexible end portion has serrations allowing the tip to be secured to the bone prior to the operation of the device.

[0006] In another embodiment of the present invention, a method of microfracturing a subchondral bone comprising the steps of providing a microfracture instrument comprising an outer sleeve having a handle; a tube coupled to and extending axially from the handle, the end of the tube being curved and including means for securing the end of the tube to a subchondral bone; a tip adjacent the curved end of the tube; and a puncture element housed within the outer sleeve and extending therethrough. In the method, a surgeon accesses the subchondral bone, removing any unwanted cartilage from the subchondral bone. Once a clean location or surgical field is developed, the microfracture instrument is placed such that its tip is on the subchondral bone; the puncture element is inserted through the microfracture instrument and is engaged against the subchondral bone so as to microfracture the bone. It will be understood that the method could be modified by placing the previously assembled device against the bone; that is the instrument pre-assembled with the puncture element is placed against bone.

[0007] In an alternative embodiment, a microfracture instrument comprising an outer sleeve having a handle and a tube coupled to and extending axially from the handle is provided. The end of the tube of the embodiment being curved and including means for securing the end of the tube to a subchondral bone. The device further comprises a puncture element housed within the outer sleeve and extending therethrough, the puncture element comprising a tip for delivering force to a bone. This embodiment, however, also includes a fluid port and means to deliver fluid from the fluid port to about the end of the puncture element tip. In use, the puncture element can translate and rotate within the outer tube to microfracture the subchondral bone providing force thereto and fluid can be delivered to the site of the bone as needed. Such fluids as anesthetics, antibiotics in fluid form, irrigation fluids, cooling fluids, growth factors, analgesics or even fluids under pressure to create or improve microfracturing or any fluids found to aid in the recovery or comfort of the patient can be useful during the type of operations to which the present invention is directed. In one embodiment, the puncture element comprises a cannula, connected to the fluid port and emerging near the tip, such that the fluid is transported therethrough. In another embodiment the puncture element comprises a fluted outer edge connected to the fluid port such that fluid traverses between the outer sleeve and the puncture element from the port to about the tip. The tip of such an embodiment would comprise appropriate edges such that the fluid can continue along the edge of the tip to the surgical theater. [0008] In any of the embodiments of the present invention the microfracture instrument can include a trigger element, such as used in a pistol, which alternatively pulls the tip proximally and releases the tip against bone to cause the microfracturing. The control offered to the user in such a device would allow for increased precision in the application of force to the bone.

[0009] In the method of use of the present invention, once the field of surgery is readied, the tip of the instrument can be placed such that the puncturing element strikes the bone generally perpendicularly to the surface of the bone. In an additional embodiment, the method can include the step of attaching a surgical drill to the puncture element and activating the drill so as to microfracture the bone or attaching a manual trigger mechanism to the puncture element and repeatedly engaging the trigger to microfracture the bone. The method, when using a device having fluid delivery means, can include the steps of continuously, repeatedly or occasionally bathing the surgical field, or a specific area thereof, with fluids designed to aid in the growth of cartilage, the prevention of infection or the comfort of the patient.

[00010] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while providing an embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[00011] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[00012] Figure 1 is a perspective view of a microfracture instrument in accordance with the present invention.

[00013] Figure 2 is a perspective view of the puncture element shown in Figure 1 and removed from the outer sleeve shown in Figure 1.

[00014] Figure 3 is a perspective view of the tip of the microfracture instrument shown in Figure 1.

[00015] Figure 3 A is a perspective view of an alternative embodiment of the tip of the microfracture instrument shown in Figure 1. [00016] Figure 4 A is a perspective view, partially cut away, of the microfracture instrument shown in Figure 1, showing the knob when the puncture element shown in Figure 2 is retracted.

[00017] Figure 4B is a perspective view of the end portion of the microfracture instrument shown in Figure 1, when the puncture element shown in Figure 2 is retracted.

[00018] Figure 4C is a perspective view of the end portion of the microfracture instrument shown in Figure 1 , showing the knob when the puncture element shown in Figure 2 is extended.

[00019] Figure 4D is a perspective view of the knob of the microfracture instrument shown in Figure 1, when the puncture element shown in Figure 2 is extended.

[00020] Figures 5A and 5B are sectional elevational views of an alternative embodiment of a device made in accordance with the teachings of the present invention.

[00021] Figure 6 is a sectional view of another alternative embodiment of a device made in accordance with the teachings of the present invention.

[00022] Figure 7 is a sectional view of another alternative embodiment of a device made in accordance with the teachings of the present invention.

[00023] Figure 8 is a sectional view of another alternative embodiment of a device made in accordance with the teachings of the present invention

[00024] Figure 9 is a partial sectional view of the puncture element of one embodiment of the present invention.

[00025] Figure 10 is an elevational view of the front of the tip of the puncture element of the embodiment of Figure 9.

[00026] Figure 11 is a partial sectional view of the puncture element of one embodiment of the present invention.

[00027] Figure 12 is an elevational view of the front of the tip of the puncture element of the embodiment of Figure 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[00028] While the present invention is susceptible of embodiment in various forms, there is shown in the drawings a number of presently preferred embodiments that are discussed in greater detail hereafter. I should be understood that the present disclosure is to be considered as an exemplification of the present invention, and is not intended to limit the invention to the specific embodiments illustrated. It should be further understood that the title of this section of this application ("Detailed Description of an Illustrative Embodiment") relates to a requirement of the United States Patent Office, and should not be found to limit the subject matter disclosed herein.

[00029] Figure 1 shows a microfracture instrument 10 for use in a microfracture technique during arthroscopic surgery of the hip and other joints and bones. The microfracture instrument 10 includes an outer sleeve 12 and an inner, flexible puncture element 14 that extends through the outer sleeve 12.

[00030] The outer sleeve 12 has a handle 16 and a rigid hollow tube 20 extending axially from the handle 16, wherein the tube 20 may be fixedly or removably attached to the handle 16. A channel 22, see figure 4A, is defined through the handle 16 and the tube 20 and is configured to receive the puncture element 14. In one embodiment (see figure 4 generally), the outer sleeve 12 has a tapered profile from the handle 16 to the hollow tube 20. Alternatively, the outer sleeve 12 may be shaped with one or more transitions from a larger diameter near the handle 16 to smaller diameter near an end portion 24 of tube 20 for among other reasons to optimize a stiffness of the outer sleeve 12 over a length thereof.

[00031] The outer sleeve 12 can be configured in accordance with the requirements for microfracturing on the joint upon which the instrument 10 will be used. Thus, depending on its intended use and the bones or joints on which it will be used, the outer sleeve can be constructed to have various sizes, shapes, curves and angles configured for use with the particular joint, such as, but not limited to, hips, shoulders, knees, elbows and ankles. Moreover, in a preferred embodiment the profile of the end portion 24 is minimized to improve joint access and positioning.

[00032] The end portion 24 of the tube 20 is also curved at a preferred angle of between approximately thirty degrees to approximately ninety degrees with respect to the tube 20 to reduce the imparting of a skive force on the subchondral bone during microfracturing. It will be understood by persons having ordinary skill in the art that while a range of angles is presented as preferred embodiment, angles of from between zero to 180 degrees are possible without departing from the novel scope of the present invention. Specifically, the angle of end portion 24 allows the end portion 24 to be positioned in a preferable substantially perpendicular configuration with the subchondral bone. In a preferred embodiment of the invention the use of a universal handle allows tubes 20 of any angle to be exchanged with a tube having an end portion of another angle (see Figure 3A); as required by the specific surgical application. The end portion 24, in a preferred embodiment, can also include a serrated edge, or end wall, 26 so as to assist in securing the end portion 24 of the instrument 10 to a subchondral bone during the microfracture procedure. It will be understood by persons having ordinary skill in the art that other means and/or tube end features, such as single or multiple anchor points or pins, and others, can assist in securing the end portion 24 to bone, without departing from the novel scope of the present invention.

[00033] In an alternative embodiment of the device of the present invention, as shown in figure 5, to further accommodate the particular joint or bone, outer sleeve 212 articulates and flexes from a straight position to a curved position with the use of wires and/or cables 240 that are arranged in the walls of the tube 220. The angle of the end portion 224 is adjustable within the range of approximately 0 to 180 degrees. A thumb wheel 260 is included on the handle 216 to allow the user to adjust the angle of the end portion 224. Of course, as will be known by persons having ordinary skill in the art, a button or slider may be used in place of a thumb wheel without departing from the novel scope of the present invention. Also, as will be known to persons having ordinary skill in the art, a different actuation assembly, such as but not limited to electronic, hydraulic or manual actuation, can be used to flex end portion 224.

[00034] The outer sleeve 12 and 212 include a channel 22 or 222 defined through the outer sleeve 12 and 212. Puncture element 14 translates and/or rotates through the channel 222 and 22. A flexible portion 30 at the end of puncture element 14 allows the puncture element 14 to pass through the angle of the end potion 224 and 24 of the tube 20 and 220. The flexible portion 30 may be fabricated from one of the group consisting of an elastomer, plastic, stainless steel, NiTi alloy, or combination thereof and can be made in such forms as a spring and others, as will be explained further below. In a further embodiment, the flexible portion 30 is configured to transmit axial loads and rotational loads to the subchondral bone. Accordingly, flexible portion 30 can be made of flexible transmission conduit such as layered, alternating helix wound wire (e.g. speedometer cable).

[00035] In the operation of the device of the present invention, a tip 27 of puncture element 14 is configured to penetrate into the subchondral bone. The tip 27 may be selected from any one of the group including a microfracture tip, a fluted drill tip, a spade drill, and/or a "K- Wire" type tip, without departing from the novel scope of the present invention. In addition, the tip 27 may take on various shapes such as: conical, tubular and serrated,. Moreover, the tip 27 may include one or more sharpened cutting edges or may have a trocar tip with one or more flat facets. In a further embodiment, the tip 27 is smooth, without cutting edges, or has a roughened sandpaper-like surface. It will be understood that a self-tapping screw, that can drill more slowly so as to reduce friction is preferred as such reduces the potential for splintering and thermal damage.

[00036] Puncture element 14 further includes a knob 28 positioned at an end opposite the tip 27. A pin 32 extends from knob 28 and is configured to allow puncture element 14 to be coupled to a standard cylindrical drill, or other rotating device, so that puncture element 14 can be rotated to drill into the subchondral bone to cause the microfracture while producing a minimal amount of sldve force. Alternatively, knob 28 can be impacted with a mallet or similar surgical instrument to extend puncture element 14 from outer sleeve 12 into the subchondral bone. Other means to advance and/or rotate the end of the puncture element 14 may be included in the handle 16, or applied externally, such as through the use of pneumatics, electronics, hydraulics, spring action, other human powered mechanisms, or any combination of these causing the necessary and sufficient translation and/or rotation. Among the types of devices that can be utilized, a screw-type configuration could be used to both translate and rotate puncture element 14 simultaneously. During drilling and/or impacting, the angle of the end portion 24 and 224 enables the puncture element 14 to microfracture the subchondral bone while preventing a skive force to skive the instrument 10 across the subchondral bone.

[00037] It will be understood by persons having skill in this art that prior to operation, the site of microfracture is prepared by removing cartilage flaps around the defected area and removing the calcified cartilage layer above the subchondral bone. The outer sleeve 16 of the device is then inserted into the joint or adjacent bone such that the end portion 224 and 24 is positioned generally perpendicular on the subchondral bone in the area intended for microfracture.

[00038] In the illustrative embodiments serrated edges 26 and 226 of the end portion 24 and 224are secured to the subchondral bone to prevent the instrument 10 from moving as a result of skive force during the microfracture procedure. The puncture element 14 is then pushed through the outer sleeve 12 until tip 27 is in contact with the subchondral bone. With tip 27 positioned against the subchondral bone, the puncture element 14 is impacted and/or drilled to create a microfracture in the subchondral bone. In one embodiment, puncture element 14 is propelled with a standard clinical drill that is coupled to pin 32 of knob 28, thereby drilling a microfracture into the subchondral bone. Alternatively, knob 28 is impacted with a mallet or similar surgical instrument to extend puncture element tip 27 from outer sleeve end portion 24 and 224 to impact the subchondral bone. In yet another embodiment, puncture element 14 is utilized to both impact and drill the subchondral bone simultaneously. During the microfracture procedure, the angle of end portion 24 and 224 with respect to the tube 20 and 220 reduces a skive force on the instrument 10, thereby preventing the instrument 10 from skiving or sliding across the subchondral bone.

[00039] The device can then be removed from the surgical field to assess the microfracture in the subchondral bone. If necessary, the process of microfracturing is repeated to create an adequate number of microfracture holes so as to cover the surface area of exposed subchondral bone.

[00040] Referring now to Figure 6, a further embodiment of the present invention is shown. In Figure 6 it will be seen that any of the devices of the previous embodiments can be used in association with a driving or motive force controlled by the physical action of the user. In Figure 6, housing 16 of Figure 1 is replaced by enclosure 300, which, as show, houses a drive nut 302 in cooperative communication with a lead screw 304. Drive nut 302 is attached to a trigger element 306, giving drive nut the motive force to advance lead screw 304. Lead screw 304 is in cooperative communication with the microfracturing tip 308 such that the activation of trigger element 306 drives tip 308 into bone, when the device is placed in its working configuration (as described in detail above). As will be understood by persons having ordinary skill in the art, the present embodiment uses elements to provide the user with the ability to transfer force to bone via tip 308, lead screw 304 and drive nut 302 as activated by the user pulling trigger 306. Such elements as a trigger return spring 310 and a translation return spring, as well as trigger pivot points 314 will be necessary and can be made in various ways and/or using various device elements as will be understood by persons having ordinary skill in the art. While a mechanical method of triggering repetitive strikes is shown, it will be understood that various means can be adapted to provide the same type of strikes, such as the use of electronics, servo motors, hydraulic drives and others, can be used without departing from the novel scope of the present embodiment.

[00041] Referring now to Figures 7 and 8, an additional element that can be adapted to any of the embodiments shown herein or any microfracturing device used for the present purposes, is shown. It is known that the introduction of fluids to a surgical field is often done to assist in the surgery and/or the comfort and well being of the patient. Such fluids as anesthetics, antibiotics in fluid form, irrigation fluids, cooling fluids, growth factors, analgesics, suspended stem cells, chondrocytes, other biologically active substances such as extra-cellular matrix, including proteoglycans, Glycosaminoglycan (GAG), chondroitin sulfate, and/or fluids under pressure so as to create or improve microfracturing, and/or any fluids (including gels) found to aid in the recovery or comfort of the patient can be useful during the type of operations to which the present invention is directed. As such, a device and method to introduce such fluids in the way necessary to assist in the surgery is shown in figures 7 and 8. It will be understood by persons having ordinary skill in the art that the term "fluid" is used in its broadest sense to include any liquid or gel substance or substances suspended in a fluid or a gel, including all of those listed above, as well pastes, as found to be able to travel within devices made in accordance with the present invention and equivalents.

[00042] Figure 8 is illustrative of a device of the present invention with a fluid loading configuration along the main axis of the device. In such a device a fluid delivery element 320, such as but not limited to a syringe, is shown with a delivery port 322 coaxial with the main axis M of the device. In such a device 318, which in this example is configured similarly to the device of Figure 6 for illustrative purposes only and not as a limitation, the puncture element 324 defines a cannula 326 through which fluid can flow. As shown in Figures 9 and 10, the cannula 326 while traversing generally centrally through the puncture element can emerge on a facet 308f of tip 308; such that the action of tip 308 is not weakened by the introduction of an opening, while still channeling fluids where needed. In Figure 7 a similar configuration is shown except that the fluid is introduced through a side arm 322s (in any manner known to the art, including the mechanical connection shown and or injection with a needle based syringe). In the embodiment of Figure 7, fluids can traverse the length of sheath 368 via flutes or channels between the interior walls of sheath 368 and puncture element 324. As shown in Figures 11 and 12, end mill 330 can be created such that fluids are carried thereabout towards tip 308 and exit via the end of channels 330c. It will be understood that such embodiment is shown as illustrative and not meant to be limiting; persons having ordinary skill in the art will understand that combinations or permutations are possible without departing from the novel scope of the present invention. [00043] As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above- described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A microfracture instrument comprising:

an outer sleeve having a handle;

a tube coupled to and extending axially from the handle, the end of the tube being curved and including means for securing the end of the tube to a subchondral bone;

a puncture element housed within the outer sleeve and extending therethrough; and wherein the puncture element can translate and rotate within the outer tube to microfracture the subchondral bone.

2. The microfracture instrument of claim 1 , where in the puncture element has a flexible end portion with a tip on the flexible end portion that allows the tip to penetrate into the bone to provide a microfracture.

3. The microfracture instrument of claim 1 , wherein the puncture element can be permanently coupled to the sleeve.

4. The microfracture instrument of claim 1 , wherein the puncture element can be removably attached to the sleeve in whole or in part.

5. The microfracture instrument of claim 1 , wherein the flexible end portion having the tip thereon is interchangeable with other end portions.

6. The microfracture instrument of claim 5, wherein the tip of the flexible end portion is interchangeable with other tips.

7. The microfracture instrument of claim 5, wherein the tip of the flexible end portion has serrations.

8. The microfracture instrument of claim 1, wherein the means for securing the end of the tube to a subchondral bone is a serrated tip of the flexible end portion.

9. A microfracture instrument comprising:

an outer sleeve having a handle;

a puncture element housed within the outer sleeve and extending therethrough, the puncture element comprising a tip for delivering force to a bone;

a fluid port and means to deliver fluid from the fluid port to about the end of the puncture element tip, and

wherein the puncture element can translate and rotate within the outer tube to microfracture the subchondral bone providing force thereto and fluid can be delivered to the site of the bone as needed.

10. The microfracture instrument of claim 9, wherein the puncture element comprises a cannula connected to the fluid port and emerging near the tip.

11. The microfracture instrument of claim 9, wherein the puncture element comprises a fluted outer edge connected to the fluid port such that fluid traverses between the outer sleeve and the puncture element from the port to about the tip.

12. The microfracture instrument of claim 9, including a trigger element that alternatively pulls the tip proximally and releases, rotates or translates, or any combination thereof, the tip against bone.

13. A method of microfracturing a subchondral bone comprising the steps of: providing a microfracture instrument comprising an outer sleeve having a handle; a tube coupled to and extending axially from the handle, the end of the tube being curved and including means for securing the end of the tube to a subchondral bone; a tip adjacent the curved end of the tube; and a puncture element housed within the outer sleeve and extending therethrough;

accessing the subchondral bone and removing any unwanted cartilage from the subchondral bone;

placing the microfracture instrument onto the subchondral bone such that the tip of the instrument is positioned against the subchondral bone;

inserting the puncture element through the microfracture instrument and engaging it against the subchondral bone so as to microfracture the bone.

14. The method of microfracturing a subchondral bone of claim 13 including the step of positioning the tip such that the puncturing element strikes the bone generally perpendicularly to the surface of the bone.

15. The method of microfracturing a subchondral bone of claim 13 including the step of attaching a drill to the puncture element and activating the drill to microfracture the bone.

16. A method of microfracturing a subchondral bone comprising the steps of:

providing a microfracture instrument comprising an outer sleeve having a handle; a tube coupled to and extending axially from the handle, the end of the tube being curved and including means for securing the end of the tube to a subchondral bone; a serrated tip adjacent the curved end of the tube; and a puncture element housed within the outer sleeve and extending

therethrough;

positioning the puncture element within the outer sleeve of the microfracture instrument; placing the microfracture instrument onto the subchondral bone such that the serrated tip of the instrument is positioned against and grasps the subchondral bone with the serrations; engaging the puncture element within the microfracture instrument against the subchondral bone so as to microfracture the bone.

17. The method of microfracturing a subchondral bone of claim 16 including the step of attaching a drill to the puncture element and activating the drill to microfracture the bone.

18. The method of microfracturing a subchondral bone of claim 16 including the step of attaching a manual trigger mechanism to the puncture element andengaging the trigger at least once to microfracture the bone.

19. The method of microfracturing a subchondral bone of claim 16 including the step of providing a fluid port and means to deliver fluid from the fluid port to about the end of the puncture element tip.

20. The method of microfracturing a subchondral bone of claim 19 including the step of providing fluid at the fluid port thereby applying fluid to the point of microfracturing of the bone.