WO2025221692A1

WO2025221692A1 - Instrumentation for preparing an ankle joint for total ankle replacement and methods of using the same

Info

Publication number: WO2025221692A1
Application number: PCT/US2025/024590
Authority: WO
Inventors: Rishin J. KADAKIA; Seyedehehngameh FATEMI; Matthew David Schultz; Samuel Fang; Christian OVESON
Original assignee: Enovis Corp
Current assignee: Enovis Corp
Priority date: 2024-04-15
Filing date: 2025-04-14
Publication date: 2025-10-23
Anticipated expiration: 2026-10-15

Abstract

An instrument system for preparing a tibia of a patient to receive a tibial component of an ankle prosthesis is provided. The instrument system may include a preparation or alignment assembly, a reamer assembly, a guide wire insertion assembly, and a flexible drill assembly. Each of the aforementioned assemblies may be operatively coupled to the tibia of the patient, directly or indirectly, to ensure proper alignment of the instrumentation for formation of a cavity about a central axis of the tibia along the coronal plane thereof.

Description

INSTRUMENTATION FOR PREPARING AN ANKLE JOINT FOR TOTAL ANKLE REPLACEMENT AND METHODS OF USING THE SAME

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63/634,100, filed on April 15, 2024, and U.S. Provisional Patent Application No. 63/689,119, filed on August 30, 2024, each of which is hereby incorporated by reference herein in its entirety.

FIELD

[0002] This disclosure relates to a device, system, and method for preparing an ankle joint for implantation of an ankle prosthesis. More specifically, this disclosure relates to a device, system, and method for preparing a cavity within an intramedullary canal within the tibia of a patient prior to implantation of a total ankle replacement device.

BACKGROUND

[0003] Current instrumentation for total ankle replacement procedures require highly invasive surgical methods that can have several short and long term disadvantages. For example, current instrumentation typically requires making an incision on the bottom of a patient’s foot, and reaming through the calcaneus, talus, and proximal tibia shaft of the patient, or alternatively, by punching a cavity within the distal tibia. These highly invasive methods, which affect areas other than the distal tibia and talus (i.e., the calcaneus or proximal tibia) may cause unnecessary trauma to the patient, which not only increases recovery time but also may damage or modify non-diseased anatomy in such a way that may temporarily or permanently hinder the patient’s quality of life. Moreover, such methods may cause unnecessary bone damage due to any unnecessary force exerted on the talus and/or tibia, or as a result of undesired movement of instruments during the surgical procedure.

[0004] Furthermore, current instrumentation systems may fail to properly limit deviation of the drill bit from the desired path along the central axis of the tibia. Drilling a cavity that does not align with the central axis of the tibia may create uneven load distributions on an implanted ankle prosthesis that could greatly decrease stability of the ankle prosthesis, potentially cause implant failure, and promote soft tissue irritation that may lead to inflammation, pain, or infection.

[0005] It is therefore desirable to provide instrumentation that more accurately and reliably prepares the ankle joint, specifically the tibial cavity, for implantation of a total ankle replacement device while minimizing damage and trauma to the ankle joint, including but not limited to the calcaneus, the talus, and the tibia.

SUMMARY

[0006] In aspects, an instrument kit for preparing a tibia of a patient to receive a tibial component of an ankle prosthesis is provided. The instrument kit may include a reamer assembly configured to be operatively contacted to the tibia of the patient, and a flexible drill assembly configured to be operatively contacted to the tibia of the patient. The reamer assembly may include a reamer guide and a reamer operatively positioned within the reamer guide, where the reamer is operable to form a first cavity within the tibia. The flexible drill assembly may include a flexible drill guide configured to be positioned within the first cavity, and a flexible drill operatively positioned within the flexible drill guide, where the flexible drill is operable to form a second cavity within the tibia for receiving a tibial component of an ankle prosthesis by entering the tibia from the distal end without affecting an anterior surface of the tibia, a posterior surface of the tibia, or the proximal end of the tibia.

[0007] In some aspects, the reamer is a ball reamer and the first cavity includes a spherical portion corresponding to a geometry of the ball reamer. In some aspects, the flexible drill assembly further includes a drill.

[0008] In some aspects, the instrument kit also includes a guide wire insertion assembly. The guide wire insertion assembly may include a guide wire insertion guide and a guide wire, where the guide wire insertion guide facilitates insertion of the guide wire along a central axis of the tibia, and where the guide wire, once inserted, guides movement of the flexible drill bit such that the second cavity is formed along the central axis of the tibia.

[0009] In some aspects, the flexible drill bit is a cannulated drill bit allowing for passage of the flexible drill bit over the guide wire. In some aspects, the guide wire is a Kirchner wire (k- wire). In some aspects, the flexible drill guide is positioned along a transverse plane of the patient. In some aspects, the second cavity is restricted to the coronal plane of the patient. [0010] In some aspects, the instrument kit also includes an alignment assembly. The alignment assembly may include an instrument alignment tray and a tibial trial fixedly attached to the alignment tray, where the instrument alignment tray is configured to extend into a gap defined between the tibia of the patient and the talus, and where the tibial trial contacts the tibia for stabilization of the alignment assembly during preparation of the ankle joint.

[0011] In some aspects, the tibial trial further includes one or more guide wire holes, wherein the guide wire holes are configured to receive a guide wire therethrough to secure the tibial trial to the tibia. In some aspects, the reamer assembly, the flexible drill assembly, and/or the guide wire assembly are configured to be releasably attached to the alignment assembly.

[0012] In another aspect, a flexible drill assembly for forming a cavity within a tibia of a patient for receiving a tibial component of an ankle prosthesis therein is provided. The flexible drill assembly may include a drill guide, a flexible drill bit, and a guide wire, where the drill guide is in operative contact with the tibia, and the flexible drill bit is operatively positioned within the drill guide and about a guide wire inserted within the tibia, such that the flexible drill bit is operable to form a cavity within the tibia for receiving a tibial component of an ankle prosthesis by entering the tibia from the distal end without affecting an anterior surface of the tibia, a posterior surf ace of the tibia, or the proximal end of the tibia.

[0013] In some aspects, the flexible drill assembly also includes a drill. In some aspects, the flexible drill bit is cannulated to allow for passage of the flexible drill bit over the guide wire. In some aspects, the guide wire is a k-wire. In some aspects, a length of the cavity is greater than 20 mm, such as up to 45 mm. In some aspects, the drill guide may include a body portion comprising a first sidewall and a second sidewall defining a gap therebetween for receiving the flexible drill bit therethrough. In some aspects, the flexible drill assembly also includes an upper protrusion configured to be received within a reciprocal channel of an alignment tool positioned within a gap defined between the tibia of the patient and the talus.

[0014] In yet another aspect, a method for preparing a tibia of a patient to receive a tibial component of an ankle prosthesis is provided. The method may include the steps of resecting a distal end of the tibia to form an access point, positioning a reamer assembly within the access point, forming a first cavity in the tibia using the reamer assembly, positioning a guide wire assembly within the access point and first cavity, advancing a guide wire within the tibia along a central axis thereof, positioning a flexible drill assembly within the access point and the first cavity, around the guide wire positioned within the tibia, and forming a second cavity, using the flexible drill assembly, without affecting an anterior surface of the tibia, a posterior surface of the tibia, or a proximal end of the tibia.

[0015] In some aspects, the method also includes the step of positioning an alignment assembly within the access point prior to positioning the reamer assembly, wherein the alignment assembly is retained within the access point for the duration of the method. In some aspects, the method also includes the step of implanting a tibial component of an ankle prosthesis within the second cavity.

[0016] In an even further aspect, a method of forming a cavity within a tibia of a patient for receiving a tibial component of an ankle prosthesis is provided. The method may include the step of forming a cavity within the tibia using a flexible drill assembly, wherein the cavity is formed without affecting an anterior surface of the tibia, a posterior surface of the tibia, or the proximal end of the tibia.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The detailed description is set forth with reference to the accompanying drawings. The use of the same reference numerals may indicate similar or identical items. Various embodiments may utilize elements and/or components other than those illustrated in the drawings, and some elements and/or components may not be present in various embodiments. Elements and/or components in the figures are not necessarily drawn to scale. Throughout this disclosure, depending on the context, singular or plural terminology may be used interchangeably.

[0018] FIG. 1A is a perspective view of joint preparation assembly, according to one or more embodiments of the present disclosure.

[0019] FIG. IB is a perspective view of the joint preparation assembly of FIG. 1A, including a tibial trial spacer, according to one or more embodiments of the present disclosure.

[0020] FIG. 2A is an exploded view of a spherical reamer guide of a spherical reamer assembly, according to one or more embodiments of the present disclosure.

[0021] FIG. 2B is a perspective view of the spherical reamer assembly of FIG. 2A, according to one or more embodiments of the present disclosure. [0022] FIG. 3 A is an exploded view of a spherical reamer assembly, according to one or more embodiments of the present disclosure.

[0023] FIG. 3B is a perspective view of the spherical reamer assembly of FIG. 3 A, according to one or more embodiments of the present disclosure.

[0024] FIG. 4A is a perspective view of a k-wire insertion assembly, according to one or more embodiments of the present disclosure.

[0025] FIG. 4B is a side view of the k-wire insertion assembly of FIG. 4B, according to one or more embodiments of the present disclosure.

[0026] FIG. 5A is a perspective view of a flexible drill assembly, according to one or more embodiments of the present disclosure.

[0027] FIG. 5B is a perspective view of the flexible drill assembly of FIG. 5 A, including a flexible drill bit, according to one or more embodiments of the present disclosure.

[0028] FIG. 5C is a side view of the flexible drill assembly of FIG. 5B, according to one or more embodiments of the present disclosure.

[0001] FIG. 6 is a flow diagram of a method for preparing an ankle joint for insertion of an ankle prosthesis, according to one or more embodiments of the present disclosure.

[0002] FIG. 7A is an exploded view of an alterative spherical reamer assembly, according to one or more embodiments of the present disclosure.

[0003] FIG. 7B is a perspective view of the spherical reamer assembly of FIG. 7A, according to one or more embodiments of the present disclosure.

[0004] FIG. 8A is a perspective view of an alternative k-wire insertion assembly, according to one or more embodiments of the present disclosure.

[0005] FIG. 8B is a side view of the k-wire insertion assembly of FIG. 8A, according to one or more embodiments of the present disclosure.

[0006] FIG. 9A is a side cutaway view of a flexible drilling assembly for use with the k-wire insertion assembly of FIGS. 8A-8B, according to one or more embodiments of the present disclosure.

[0007] FIGS. 9B-9C are side cutaway views of the flexible drilling assembly of FIG. 9A, in use, according to one or more embodiments of the present disclosure.

[0008] FIG. 10A is a perspective view of a uniplanar drill assembly, according to one or more embodiments of the present disclosure. [0009] FIG. 1 OB is a perspective cutaway view of the uniplanar drill assembly of FIG. 10A, according to one or more embodiments of the present disclosure.

[0010] FIG. 11 is a side view of the uniplanar drill bit of the uniplanar drill assembly of FIGS. 10A-10B, according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

[0011] The disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the disclosure are shown. This disclosure may, however, be embodiment in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0012] Certain terminology is used in the following description for convenience only and is not limiting. The words “front,” “upper,” and “lower” designate directions in the drawings to which reference is made. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, or c, or combinations thereof.

[0013] The coronal, sagittal, and axial planes are referenced throughout this disclosure. These directional terms are used according to their generally accepted definitions as used in the medical field unless explicitly clarified herein. The terms superior/inferior, medial/lateral, and posterior/anterior, distal/proximal are similarly used according to the generally accepted definitions as used in the medical field, unless explicitly clarified herein. The drawings include further clarifications regarding these directions and planes to the extent is believed necessary. The terms top/bottom are sometimes used interchangeably with superior/inferior, and the term side is sometimes used interchangeably with medial/lateral.

[0014] A uniplanar drill assembly, including a uniplanar drill bit and drill, are referenced throughout this disclosure. These terms are defined herein to include any device used within the medical profession to prepare bone for total ankle replacement. Therefore, the uniplanar drill assembly may include any device used to create a bore or cut in bone, such as a drill, a reamer, a broach, a rasp, a milling cutter, a bur, or any other device as recognized by one of ordinary skill in the art.

[0015] A flexible drill assembly, including a flexible drill and a flexible drill guide, are referenced throughout this disclosure. These terms are defined herein to include any device used within the medical profession to prepare bone for total ankle replacement. Therefore, the flexible drill assembly may include any device used to create a bore or cut in bone, such as a drill, a reamer, a broach, a rasp, a milling cutter, a bur, or any other device as recognized by one of ordinary skill in the art.

[0016] A reamer assembly and reamer drill guide are referenced throughout this disclosure. These terms are included for the purpose of differentiating between the flexible drill assembly and the flexible drill but are defined herein to include any device used within the medical profession to prepare bone for total ankle replacement. Therefore, the reamer assembly may include any device used to create a bore or cut in bone, such as a drill, a reamer, a broach, a rasp, a milling cutter, a bur, or any other device as recognized by one of ordinary skill in the art.

[0017] Total ankle replacement is a procedure that is used for patients with, for example, osteoarthritis, post-traumatic arthritis or rheumatoid arthritis. Depending on the implant and geometries of the tibia, a cavity is drilled to provide space for an ankle prosthesis to be implanted. In some embodiments, the cavity is prepared along the anatomical axis of the tibia to allow for insertion of the prosthesis in the tibial canal.

[0018] The present disclosure allows for preparation of the intramedullary canal at the distal tibia without impacting the proximal tibia or the anterior/posterior sides of the tibia. More specifically, the systems and methods described herein allow for preparation of the intramedullary canal at the distal tibia without the need for invasive procedures that require that the ankle joint be accessed through the bottom of a patient’s foot. The systems and methods described herein therefore reduce trauma to the patient’s foot and ankle, reducing recovery time and mitigating risks of long-term or permanent nerve damage thereto.

[0019] A system for preparing an ankle joint for insertion of a total ankle replacement prosthesis may be better understood with reference to FIGS. 1 A-5C.

[0020] In embodiments, as shown in FIGS. 1A-1B, ajoint preparation assembly 100 is provided for forming a cavity along a central axis of a patient’s tibia for receiving a tibial stem portion of an ankle prosthesis therein. The joint preparation assembly 100, or alignment assembly, may be positioned within the ankle for the duration of the preparation procedure, and may guide the alignment of various instruments and instrument assemblies in preparing the ankle joint. [0021] In embodiments, the joint preparation assembly 100 may include a tibial plate 102, which extends into a gap 30 defined between the patient’s tibia 10 and talus 20 after a preliminary blunt resection thereof. The blunt resection may be performed using any device known by those in the art for creating a bore or for cutting bone, such as a drill, a reamer, a broach, a rasp, a milling cutter, a bur, or any other bone-cutting device may be used to resect the tibia 10 and the talus 20. The plate 102 may extend into the gap so that an upper surface 108 thereof is in contact with a distal end 12 of the tibia 10. A bottom surface 110 of the plate may face, but not contact, the talus 20. The plate 102 may also include an instrumentation passage 112 spanning between the upper surface 108 and lower surface 110 of the plate, and a receiving channel 114 extending from the instrumentation passage 112 in a direction towards the tibial trial 104. The instrumentation passage 112 and the receiving channel 114 may be sized and shaped to receive one or more guides and/or instrumentation assemblies for further preparation of the ankle joint for inserting an ankle prosthesis, such as those described herein. For example, the instrument passage 112 and receiving channel 114 may together form a keyhole-shaped opening in the tray 102. The instrument passage 112 may be sized and/or shaped to receive an operable portion of an instrument assembly therethrough, while the receiving channel 114 is sized and/or shaped to receive an elongated body portion of said instruments.

[0022] In embodiments, the tibial trial 104 is fixedly attached to and extending upward from the plate 102. The plate 102 and tibial trail 104 may be substantially perpendicular to each other. In some embodiments, the tibial trial 104 may be sized and shaped similarly to a stem portion of an ankle prosthesis (not shown), to be placed within the intramedullary canal of the tibia 10. The tibial trial 104 may therefore provide surgeons with a reference regarding the appropriate size of implant to be provided to the patient, without needing to trial various implant sizes after the ankle joint has been prepared for implantation.

[0023] In some embodiments, the tibial trial 104 may also help to secure the joint preparation assembly 100 within the patient’s ankle joint so that the assembly 100 remains stable therein throughout the duration of the preparation procedure. For example, the tibial trial 104 may abut the patient’s tibia 10 to provide stability for the assembly in use. The tibial trial 104 may also include one or more openings 116 that permit passage of a k-wire (not shown) therethrough. The k-wire, passing through the one or more openings 116, may be secured within the tibia 10 for enhanced stability of the joint preparation assembly 100 during use. Any suitable k-wire may be used and secured within the tibia 10 according to any suitable method as would be recognized by those skilled in the art.

[0024] In embodiments, the joint preparation assembly 100 also includes a quick-connect 106 for facilitating attachment of one or more guides and/or instrumentation assemblies for further preparation of the ankle joint, such as those described herein. In some embodiments, as shown in FIGS. 1A-1B, the quick-connect includes a pair of protrusions 118 defining a receiving gap 120 therebetween. The receiving gap 120 may be sized and shaped to receive a corresponding component of a guide and/or instrument therein for use with the joint preparation assembly 100. In some embodiments, each of the protrusions 118 also includes a ledge 119, extending into the gap 120, for further securing a corresponding component of a guide and/or instrument within the receiving gap 120 for enhanced stability during use.

[0025] In some embodiments, as shown in FIG. IB, the joint preparation assembly 100 also includes a spacer 122 for securing the plate 102 against the tibia 10 during preparation of the joint for implantation of an ankle prosthesis. The spacer 122 may include a first end 124 remaining outside of the patient’s body and a second end 126 configured to be inserted into the gap 30 between the tibia 10 and the talus 20. The second end 126 may have a smaller width than the first end 124 to permit placement of the spacer 122 within the gap 30. When in place, the second end of the spacer 122 contacts the bottom surface 110 of the plate 102 on a top side 128, and the talus 20 on a bottom side 130, thereby keeping the plate 102 in place.

[0026] Following initial preparation of the ankle joint with the joint preparation assembly 100, a spherical reamer assembly 200 may be provided for forming a preliminary cavity within the tibia 10. The reamer assembly 200 is shown in greater detail in FIGS. 2A-3B. As shown in FIGS. 2A-2B, the spherical reamer assembly 200 may include a spherical reamer guide 202 which is configured to be attached to the joint preparation assembly 100 via a connecting portion 204. In embodiments, the connecting portion 204 includes an inwardly facing protrusion 206, a body portion 208, and an outwardly facing protrusion 210. When assembled, as shown in FIG. 2B, the inwardly facing protrusion 206 is retained within the gap 120 defined between the protrusion 118 of the quick connect 106. Further means for securing the spherical reamer guide 202 to the joint preparation assembly 100 may implemented in addition to (or in the alternative to) the mating between the quick connect 106 and the connecting portion 204. For example, one or more screws may be provided for further securing the spherical reamer guide 202 to one or more portions of the joint preparation assembly 100. Other securement and/or attachment means that would be appreciated by those of ordinary skill in the art are considered to be alternatives within the scope of the present disclosure.

[0027] In embodiments, the spherical reamer guide 202 also includes a guide channel 212 having a channel opening 214 for receiving and retaining a spherical reamer 220. The guide channel 212 may align with the receiving channel 114 of the tray 114 for passage of the spherical reamer 320 therethrough. In some embodiments, the guide channel 212 may be cylindrical. In other embodiments, the guide channel 212 may be any size or shape suitable for receiving and retaining the spherical reamer 220 therein.

[0028] As shown in FIGS. 3A-3B, the spherical reamer may include a body 222 having a first end 224 and a second end 226 having a spherical reamer head 228 attached thereto. In some embodiments, the reamer body 222 and spherical reamer head 228 are formed as a unitary body. In other embodiments, the reamer body 222 and head 228 are separate components that together form the reamer 220 when assembled.

[0029] As shown in FIG. 3A, the body 222 of the spherical reamer 220 may be received by the opening 214 of the channel 212. While the reamer 220 is being inserted into the guide 102, via the opening 214 and the channel 212, the head 228 sits below the plate 102 and the instrumentation passage 112 defined therein. As the reamer 220 is advanced upward, the reamer head 228 passes through the instrumentation passage 112 and the body 222 passes through the receiving channel 114 such that, when assembled, the reamer 220 rests on the top surface 108 of the plate 102, as shown in FIG. 3B. The position of the reamer 220, specifically the spherical reamer head 228, within the instrumentation passage 112 permits rotation of the reamer 220 in a manner that is effective to form a spherical (or partially spherical) cavity within the tibia 10.

[0030] Once assembled with the joint preparation assembly 100, the spherical reamer assembly 200 may be operated to form a preliminary cavity 14 within the distal end 12 of the tibia 10. In these embodiments, the preliminary cavity is spherical. However, it would be understood that non-spherical cavities may be effective for the same purpose, i.e., preparing the tibia 10 to accommodate additional instrumentation. That is, the cavity may be any size and/or shape necessary to achieve said purpose, and non-spherical reamers may be utilized to form such non-spherical cavities. [0031] A drill (not shown), or other means for effectuating rotation of the spherical reamer 220 may be attached to the first end 224 of the reamer body 222 and operated to cause the spherical reamer head 228 to form a spherical (or partially spherical) cavity 14 (as shown in FIGS. 4A-5C) within the tibia 10. This spherical cavity 14 may be sized and shaped to receive further instrumentation, such as the k-wire insertion assembly 300 and drilling assembly 400 as described herein.

[0032] For example, as shown in FIGS. 4A-4B, a k-wire insertion assembly 300 may be provided following the spherical resection of the tibia 10. As with the spherical reamer assembly 200, the k-wire insertion assembly 300 may be attached to the joint preparation assembly 100 to ensure proper placement and stability of the k-wire insertion assembly 300 in use.

[0033] In embodiments, the k-wire insertion assembly 300 includes a k-wire guide 302 having an elongated portion 304 defining a first end 306 and a second end 308. The first end 306 includes an aligning portion 310 having an aligning protrusion 312 extending therefrom in a downward direction. In some embodiments, as shown, the aligning protrusion 312 is a cylindrical protrusion, however a protrusion of any suitable size and/or shape is contemplated herein. The aligning protrusion 312 may also include a through-hole 314 for receiving a k-wire 320 therein, as shown in FIG. 4 A.

[0034] The second end 308 includes a guiding portion 316 having a guide protrusion 318 extending upward therefrom and into the spherical cavity 14 within the distal end 12 of the tibia 10. In some embodiments, as shown, the aligning protrusion 314 is also cylindrical, however any suitable size and/or shape protrusion may be used. The guiding portion 316 and guiding protrusion 318 are sized and shaped to receive the k-wire 320 therethrough for insertion into the tibia 10. In embodiments, the guiding portion 316 is sized and shaped to fit securely in the instrumentation passage 112 of the plate 102 of the joint preparation assembly 100.

[0035] For example, the guiding portion 316 may be circular and sized to fit within the circular opening of the instrumentation passage 112. In embodiments where the instrumentation passage 112 is not circular, the guiding portion 316 is shaped similarly to the shape of the instrumentation passage 112. In some embodiments, the base 316a of the guiding portion 316 is slightly larger than the instrumentation passage 112 and tapers in a direction towards the guiding protrusion 318. The base 316a of the guiding portion 316 may therefore rest against the bottom may protrude from the top surface 108 of the tray 102 and into the spherical cavity 14 formed within the tibia 10.

[0036] Once the k-wire insertion assembly 300 is aligned, such that the guiding protrusion 318 is within the spherical cavity 14, a tip 322 of the k-wire 320 is advanced into the tibia 10 along a central axis thereof. In some embodiments, the tip 322 is a sharp end so that it may more effectively enter and pass through the bone. Opposite from the tip 322 of the k-wire 320 is a blunt end 342 which may be operably connected to an instrument (not shown) which is suitable to advance the k-wire 320 into the tibia 10, as would be appreciated by those of skill in the art. [0037] As the k-wire 320 is advanced into the tibia 10, as shown in FIG. 4B, the k-wire 320 may disengage from the aligning protrusion 312 depending on the length of the k-wire. That is, the k-wire 320 may disengage with the through-hole 314, thereby disengaging the k-wire 320 from the aligning protrusion 312. However, in some embodiments (not shown) the k-wire 320 may be long enough so as to maintain contact with the aligning protrusion 312, via the through- hole 314, throughout the insertion process. The length of the k-wire 320 to be inserted into the tibia 10 may depend on various factors, including by not limited to the patient’s anatomy (i.e., the size of the patient’s tibia) and/or the length of the tibial stem of the ankle prosthesis to be implanted.

[0038] Following placement of the k-wire 320 to a desired length, the k-wire 302 guide may be removed from the joint preparation assembly 100, leaving the k-wire 320 in place.

[0039] As shown in FIGS. 5A-5C, a drilling assembly 400 may then be provided and attached to the joint preparation assembly 100. In embodiments, the drilling assembly includes a guide 402 having a first side 404 and a second side 406 defining an opening 408 for a drilling channel 410 therebetween. The guide 402 may also include a securement protrusion 412 extending from a top surface 414 thereof for attaching and securing the guide 402 to the joint preparation assembly 100. More specifically, the securement protrusion 412 is sized and shaped to be held within the receiving channel 114 of the joint preparation assembly. In some embodiments as shown, the securement protrusion 412 is cylindrical or substantially cylindrical. However, other means of securing the guide 402 to the joint preparation assembly 100 may be implemented. For example, the guide 402 may include a component configured for attachment to the quick-connect 106 of the joint preparation assembly 100. In embodiments, the guide 402 also includes a window 416 for visualizing alignment of the k-wire 320 and a drill bit 420 within the assembly 400. Once the guide 402 is secured to the joint preparation assembly 100, a flexible drill bit 420 may be inserted into the guide 402 via a bottom opening 418 in the guide 402 defined between the first side wall 404 and the second side wall 406 thereof.

[0040] In embodiments, the flexible drill bit 420 has a first end 422 configured for connection to a surgical drill (not shown) and a second end 424 opposite the first end. The drill may be a hand drill, an electric drill, a pneumatic drill, or other drill known by those in the art. The drill bit 420 includes a fixed body portion 426 at the first end 422 and a drill bit head 430 at the second end 424, with a flexible portion 428 spanning therebetween. Implementation of a drill bit 420 having a flexible portion 428 may aid the surgeon in accessing the tibia 10 while eliminating the need to drill through the calcaneus, talus, and tibia. That is, the flexible portion 428 of the drill bit 420 may be maneuvered within the gap 30 between the tibia 10 and the talus 20 to access the desired drilling location within the tibia 10 (i.e., along a central access thereof). [0041] In some embodiments, the flexible portion 428 is a unitary flexible sheath that is capable of bending and flexing as needed to navigate the drill bit head 430 to the proper position for drilling the cavity within the tibia 10. In other embodiments, the flexible portion 428 is formed of a plurality of disk-shaped segments that permit bending and flexing of said flexible portion 428.

[0042] The positioning of the flexible drill bit 420 may be guided by the k-wire 320. For example, the drill bit 420 may define a channel (not shown) for receiving the k-wire 320 therethrough. As the drill bit 420 is advanced, the drill bit 420 travels along the path of the k- wire to form a cavity within the patient’s tibia 10 that is properly centered and aligned for insertion of a stem portion of an ankle prosthesis therein.

[0043] While it may be possible to access and drill into the tibia with existing fixed-angle drill bits, said drill bits are not capable of forming a cavity having sufficient depth to receive a stem portion of an ankle replacement device therein. For example, fixed-angle drill bits do not provide sufficient drilling depth for forming a cavity within the tibia that can receive a stem portion of an ankle replacement device therein. In contrast, use of a flexible drill bit such as that described herein enables a surgeon to drill a cavity having any desired depth for receiving a tibial portion of an ankle prosthesis therein. In some embodiments, the flexible drill bit 420 may be used to drill a 45 mm long cavity, which is more than twice the length of cavity achievable with a fixed-angle drill. In some embodiments, the flexible drill bit 420 may be used to drill a cavity exceeding 45 mm.

[0044] The instrument systems described herein, including but not limited to those of FIGS. 1A-5C, are designed to limit trauma to the patient’s ankle joint. For example, unlike existing procedures, use of the drill guides and assemblies disclosed herein permits surgeons to access the ankle joint from a side thereof, rather than through the calcaneus and talus or a proximal end of the tibia. This improves recovery time while also mitigating the risk of long-term or permanent damage associated with existing ankle preparation procedures.

[0045] In embodiments, a method 500 for preparing an ankle joint and implanting an ankle prosthesis is provided, using the instrumentation described with respect to FIGS. 1 A-5C.

[0046] In embodiments, the method 500 includes forming an access location (510) within the patient’s ankle joint by partially resecting the patient’s tibia 10 and talus 20. The access location may be formed using any device known by those in the art for creating a bore or for cutting bone, such as a drill, a reamer, a broach, a rasp, a milling cutter, a bur, or any other bone-cutting device may be used to resect the tibia 10 and the talus 20. Removal of the resected portions of the tibia 10 and the talus 20, respectively, creates a space 30 within the ankle joint configured to receive instrumentation therein for further preparing the ankle joint for implantation of an ankle replacement prosthesis. The access location may be sized and shaped to receive instrumentation and/or the ankle replacement prosthesis.

[0047] After the access location is formed, a reamer assembly is positioned within the access location (520). A first cavity may then be formed (530) within the tibia using the reamer assembly. In embodiments, the geometry of the first cavity corresponds to a size and/or shape of additional instrumentation (e.g., a guide wire insertion assembly or a drill assembly) for further preparation of the ankle joint.

[0048] Following formation of the first cavity, the reamer assembly is removed and a guide wire insertion assembly is placed within the access location (540). A guide wire may then be advanced, through the insertion assembly, into the tibia of the patient (550). The guide wire may be placed along the central access of the tibia to guide formation of the second cavity at an optimal location within the tibia for receiving a tibial portion of an ankle prosthesis. Upon placing the guidewire, the guidewire assembly (less the guidewire) may be removed. [0049] A drill assembly may then be positioned within the access location and first cavity about the guidewire (560). The drill assembly may then be operated to form a second cavity (570) within the tibia along a central access thereof, guided by the positioning of the guide wire. The second cavity is therefore formed by entering the tibia from the distal end without affecting the anterior surface of the tibia, the posterior surface of the tibia, or the proximal end of the tibia. After removal of the drill assembly, an ankle prosthesis may be implanted within the ankle (580), with a tibial portion thereof residing within the second cavity.

[0050] In some embodiments, the method may also include providing an alignment assembly, or a joint preparation assembly, within the access location. The alignment assembly may be retained within the access location for the duration of the procedure, such that the reamer assembly, guide wire assembly, and drill assembly are all attached to and then removed from the alignment assembly. Use of an alignment assembly, to which additional instrumentation assemblies are attached, may reduce the complexity and duration of the ankle preparation procedure.

[0051] The aforementioned method may also be performed using alternative embodiments of the instrumentation systems described in FIGS. 1A-5C.

[0052] An alternative spherical reamer assembly 600 is shown in FIGS. 7A-7B. The reamer assembly 600 may include a tray 602 and a tibial trial portion 604 attached thereto via a joining portion 606. In some instances, the tray 602 and the tibial trail portion 604 may be generally perpendicular to each other. The tray 602 may also be removably attached to a connection portion 608, where the connection portion 608 extends into the gap 30 between the tibia 10 and talus 20 to more stably secure the reamer assembly 600 within the gap.

[0053] In embodiments, the tray 602 includes a instrumentation passage 610 extending between a top surface 612 and a bottom surface 614 of the tray 602. The instrumentation passage 610 may be sized and shaped to receive a spherical reamer, such as reamer 626, therein. For example, the instrumentation passage 610 may have a keyhole shape, with a circular opening 610a within the center of the tray 602 and an elongated opening 610b extending away from the center in a direction towards the tibial trail 604. The connection portion 608, which has one or more grooves 616 configured to receive and mate with reciprocal protrusions (not shown) on the bottom surface 614 of the tray 602, may also include an instrumentation opening 618 sized and shaped similarly to the instrumentation passage 610 of the tray. The tibial trial portion 604 may also define a channel 620 therein adjacent the joining portion 606 configured to receive instrumentation (e.g., a reamer) therethrough. This channel 620 may be further defined by an elongated opening 622 within the connecting portion 608. In some embodiments, the tibial trail 604 includes one or more through holes 624 for receiving a k-wire therethrough for further securing the reamer assembly 600 to the tibia 10. The use of one or more k-wires may ensure that the reamer assembly 600 moves minimally (if not at all) during operation of the reamer 626. [0054] In embodiments, the reamer 626 is a spherical reamer for preparing a preliminary cavity within the patient’s tibia. The reamer 626 includes an elongated body 628 having a first end 630 configured to attach to a drill (or other tool for effecting rotation of the reamer 626) and a second end 632 having a ball reamer head 634 attached thereto. The body 628 may also have a stopper 636 positioned between the first end 630 and second end 632 to properly align the reamer 626 within the cavity 30. The stopper 636 may also help to prevent unwanted lateral movement of the reamer 626 in use.

[0055] In some embodiments, the body 628, head 634, and stopper 636 are integrally formed as a single component. In other embodiments, the body 628, head 634, and stopper 363 are separate components that are assembled to form the reamer 626.

[0056] In use, as shown in FIG. 7B, the reamer 626 may be positioned within the instrumentation passage 610 of the tray 602 to form a shallow spherical (or partially spherical) cavity within the tibia 10, as previously described herein. For example, the reamer 626 may pass through the channel 620 and rest within or on top of the instrument passage 610, such that the head of the reamer 626 is positioned within the circular opening 610a of the tray 602. Placement of the head 634 of the reamer 626 within the circular opening 610a of the tray 602 permits rotational movement of the reamer 626 while maintaining proper alignment thereof with respect to the tibia 10. In embodiments, the stopper may abut the outside of the channel 620 in the tibial trial 604, thereby restricting the length of the reamer body 628 and head 634 can extend into the tray 602.

[0057] The shallow cavity may have a geometry that corresponds to a size and shape of a drill guide and drill assembly, as described herein. While the reamer 626 is described herein as a spherical reamer, or a ball reamer, it would be understood that other reamers as known in the art would be suitable for use with the systems and methods described herein. [0058] Following preparation of the cavity, a drilling assembly 700, as shown in FIGS. 8A- 9C, may be introduced.

[0059] In embodiments, the drilling assembly 700 includes a drill guide 702 having a first end 704 and a second end 706. Extending in an upward direction, from the first end 704, is a stabilizing portion 708 for maintaining the position of the guide 702 with respect to the patient’s tibia 10. Extending upward from the guide 702 and the second end 706 is a spherical portion 710 sized and shaped to fit within the spherical cavity 14 formed in the tibia 10 by the reamer 626 as previously described with respect to FIGS. 7A-7B.

[0060] In some embodiments, the spherical portion 710 includes an opening 712 sized for passage of a k-wire therethrough. As shown in FIG. 8B, the opening 712 may be located at a terminal end of a passage 714 extending through the spherical portion 710 of the guide. The passage 714 and opening 712 may also be sized and shaped to receive a drill bit therethrough, as shown in FIGS. 9A-9C.

[0061] In embodiments, such as those of FIGS. 9A-9C, the drill assembly 100 also includes a flexible drill bit 720 sized and shaped to drill a cavity within the patient’s tibia. The flexible drill bit 720 may include a body portion 722, the body portion having a first end 724 and a second end 726. Attached to the body 722, in a direction towards the second end 726, is a flexible portion 728 having a drill bit head 730 attached thereto. A drill 734 may be attached to a connecting portion 732 at the first end 724 of the drill bit body 722. In some embodiments, the flexible portion 728 is a unitary flexible sheath that is capable of bending and flexing as needed to navigate the drill bit head 730 to the proper position for drilling the cavity within the tibia 10. In other embodiments, the flexible portion 728 is formed of a plurality of disk-shaped segments that permit bending and flexing of said flexible portion 728.

[0062] In use, a k-wire 716, having a sharp tip 718 for anchoring within the bone, may be introduced to the tibia 10 through a passage (not shown) within the body 722 of the drill bit 720, as shown in FIG. 9A. After the k-wire 716 is anchored in the tibia 10, as shown in FIG. 9B, the drill bit 720 may be advanced into the tibia 10 along the path of the k-wire 716, as shown in FIG. 9C, to form a cavity within the tibia 10 capable of receiving a stem of a total ankle replacement implant therein.

[0063] In some embodiments, a uniplanar drill assembly may be used to form the cavity within the patient’s tibia. For example, as shown in FIGS. 10A-10B, a uniplanar drill assembly 800 may have a guide 802 and a tibial trial 804 extending in an upward direction from the guide 802. The guide 802 may define a channel 806 therein for receiving a drill bit, such as the uniplanar drill bit 810 described herein. The tibial trail 804 may align with the tibia 10 to provide stability to the guide 802. In some embodiments, the tibial trial 804 has one or more passages 808 extending therethrough for receiving a k-wire (not shown). One or more k-wires may extend through the passages 808 to further secure the tibial trial 804 to the tibia 10 during operation of the uniplanar drill 810.

[0064] In embodiments, as shown in greater detail in FIG. 11, the uniplanar drill 810 has a body 812 defining a first end 814 and a second end 816. The first end 814 may be configured for attachment to a drill 824, while a drill bit head 820 is positioned at the second end 816. A flexible sleeve 818 may be provided between the drill bit head 820 and the body 812 of the drill bit 810, which permits proper placement of the drill bit 810 within the ankle joint for drilling of a cavity within the patient’s tibia 10. The drill assembly 800 may also constrain motion of the drill bit 810 to the sagittal plane such that the drill bit 810 is only permitted to move horizontally within the sagittal plane to align the drill bit 810 within the patient’s ankle joint.

[0065] Having thus described the present systems and methods in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the concepts and principles embodied therein.

[0066] It is also to be appreciated that numerous embodiments incorporating only part of the embodiments discussed herein are possible which do not alter, with respect to those parts, the concepts and principles embodied therein.

[0067] The present embodiments and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the systems and methods being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to these embodiments which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.

EMBODIMENTS

[0068] Some embodiments of the present disclosure can be described in view of one or more of the following: [0069] Embodiment 1 . An instrument kit for preparing a tibia of a patient to receive a tibial component of an ankle prosthesis, the kit comprising: a reamer assembly configured to be operatively contacted to the tibia of the patient, the reamer assembly comprising: a reamer guide; and a reamer operatively positioned within the reamer guide; wherein the reamer is operable to form a first cavity within the tibia; a flexible drill assembly configured to be operatively contacted to the tibia of the patient, the flexible drill assembly comprising: a flexible drill guide configured to be positioned within the first cavity; and a flexible drill operatively positioned within the flexible drill guide; wherein the flexible drill is operable to form a second cavity within the tibia for receiving a tibial component of an ankle prosthesis by entering the tibia from the distal end without affecting an anterior surface of the tibia, a posterior surf ace of the tibia, or the proximal end of the tibia.

[0070] Embodiment 2. The instrument kit of Embodiment 1, wherein: the reamer is a ball reamer; and the first cavity includes a spherical portion corresponding to a geometry of the ball reamer.

[0071] Embodiment 3. The instrument kit of Embodiment 1 or Embodiment 2, wherein the flexible drill assembly further comprises a drill.

[0072] Embodiment 4. The instrument kit of any one of Embodiments 1 to 3, further comprising a guide wire insertion assembly, the guide wire insertion assembly comprising: a guide wire insertion guide; and a guide wire; wherein the guide wire insertion guide facilitates insertion of the guide wire along a central axis of the tibia; and wherein the guide wire, once inserted, guides movement of the flexible drill bit such that the second cavity is formed along the central axis of the tibia.

[0073] Embodiment 5. The instrument kit of any one of Embodiments 1 to 4, wherein the flexible drill bit is a cannulated drill bit allowing for passage of the flexible drill bit over the guide wire.

[0074] Embodiment 6. The instrument kit of any one of Embodiments 1 to 5, wherein the guide wire is a Kirchner wire (k-wire).

[0075] Embodiment 7. The instrument kit of any one of Embodiments 1 to 6, wherein the flexible drill guide is positioned along a transverse plane of the patient.

[0076] Embodiment 8. The instrument kit of any one of Embodiments 1 to 7, wherein the second cavity is restricted to the coronal plane of the patient. [0077] Embodiment 9. The instrument kit of any one of Embodiments 1 to 8, further comprising an alignment assembly comprising: an instrument alignment tray; and a tibial trial fixedly attached to the alignment tray; wherein the instrument alignment tray is configured to extend into a gap defined between the tibia of the patient and the talus; and wherein the tibial trial contacts the tibia for stabilization of the alignment assembly during preparation of the ankle joint.

[0078] Embodiment 10. The instrument kit of any one of Embodiments 1 to 9, wherein the tibial trial further comprises one or more guide wire holes, wherein the guide wire holes are configured to receive a guide wire therethrough to secure the tibial trial to the tibia.

[0079] Embodiment 11. The instrument kit of any one of Embodiments 1 to 10, wherein the reamer assembly, the flexible drill assembly, and/or the guide wire assembly are configured to be releasably attached to the alignment assembly.

[0080] Embodiment 12. A flexible drill assembly for forming a cavity within a tibia of a patient for receiving a tibial component of an ankle prosthesis therein, the flexible drill assembly comprising: a drill guide; a flexible drill bit; and a guide wire; wherein the drill guide is in operative contact with the tibia, and the flexible drill bit is operatively positioned within the drill guide and about a guide wire inserted within the tibia, such that the flexible drill bit is operable to form a cavity within the tibia for receiving a tibial component of an ankle prosthesis by entering the tibia from the distal end without affecting an anterior surface of the tibia, a posterior surf ace of the tibia, or the proximal end of the tibia.

[0081] Embodiment 13. The flexible drill assembly of Embodiment 12, further comprising a drill.

[0082] Embodiment 14. The flexible drill assembly of Embodiment 12 or 13, wherein the flexible drill bit is cannulated to allow for passage of the flexible drill bit over the guide wire. [0083] Embodiment 15. The flexible drill assembly of any one of Embodiments 12 to 14, wherein the guide wire is a k-wire.

[0084] Embodiment 16. The flexible drill assembly of any one of Embodiments 12 to 15, wherein a length of the cavity is greater than 20 mm, such as up to 45 mm.

[0085] Embodiment 17. The flexible drill assembly of any one of Embodiments 12 to 16, wherein the drill guide comprises: a body portion comprising a first sidewall and a second sidewall defining a gap therebetween for receiving the flexible drill bit therethrough. [0086] Embodiment 18. The flexible drill assembly of any one of Embodiments 12 to 17, further comprising an upper protrusion configured to be received within a reciprocal channel of an alignment tool positioned within a gap defined between the tibia of the patient and the talus. [0087] Embodiment 19. A method for preparing a tibia of a patient to receive a tibial component of an ankle prosthesis, the method comprising: resecting a distal end of the tibia to form an access point; positioning a reamer assembly within the access point; forming a first cavity in the tibia using the reamer assembly; positioning a guide wire assembly within the access point and first cavity; advancing a guide wire within the tibia along a central axis thereof; positioning a flexible drill assembly within the access point and the first cavity, around the guide wire positioned within the tibia; and forming a second cavity, using the flexible drill assembly, without affecting an anterior surface of the tibia, a posterior surface of the tibia, or a proximal end of the tibia.

[0088] Embodiment 20. The method of Embodiment 19, further comprising the step of positioning an alignment assembly within the access point prior to positioning the reamer assembly, wherein the alignment assembly is retained within the access point for the duration of the method.

[0089] Embodiment 21. The method of Embodiment 19 or 20, further comprising the step of implanting a tibial component of an ankle prosthesis within the second cavity.

[0090] Embodiment 22. A method of forming a cavity within a tibia of a patient for receiving a tibial component of an ankle prosthesis, the method comprising: forming a cavity within the tibia using a flexible drill assembly, wherein the cavity is formed without affecting an anterior surface of the tibia, a posterior surface of the tibia, or the proximal end of the tibia.

Claims

CLAIMS That which is claimed is:

1. An instrument kit for preparing a tibia of a patient to receive a tibial component of an ankle prosthesis, the kit comprising: a reamer assembly configured to be operatively contacted to the tibia of the patient, the reamer assembly comprising: a reamer guide; and a reamer operatively positioned within the reamer guide; wherein the reamer is operable to form a first cavity within the tibia; a flexible drill assembly configured to be operatively contacted to the tibia of the patient, the flexible drill assembly comprising: a flexible drill guide configured to be positioned within the first cavity; and a flexible drill operatively positioned within the flexible drill guide; wherein the flexible drill is operable to form a second cavity within the tibia for receiving a tibial component of an ankle prosthesis by entering the tibia from the distal end without affecting an anterior surface of the tibia, a posterior surf ace of the tibia, or the proximal end of the tibia.

2. The instrument kit of claim 1, wherein: the reamer is a ball reamer; and the first cavity includes a spherical portion corresponding to a geometry of the ball reamer.

3. The instrument kit of claim 1, wherein the flexible drill assembly further comprises a drill.

4. The instrument kit of claim 1, further comprising a guide wire insertion assembly, the guide wire insertion assembly comprising: a guide wire insertion guide; and a guide wire; wherein the guide wire insertion guide facilitates insertion of the guide wire along a central axis of the tibia; and wherein the guide wire, once inserted, guides movement of the flexible drill bit such that the second cavity is formed along the central axis of the tibia.

5. The instrument kit of claim 4, wherein the flexible drill bit is a cannulated drill bit allowing for passage of the flexible drill bit over the guide wire.

6. The instrument kit of claim 5, wherein the guide wire is a Kirchner wire (k-wire).

7. The instrument kit of claim 1, wherein the flexible drill guide is positioned along a transverse plane of the patient.

8. The instrument kit of claim 1, wherein the second cavity is restricted to the coronal plane of the patient.

9. The instrument kit of claim 1, further comprising an alignment assembly comprising: an instrument alignment tray; and a tibial trial fixedly attached to the alignment tray; wherein the instrument alignment tray is configured to extend into a gap defined between the tibia of the patient and the talus; and wherein the tibial trial contacts the tibia for stabilization of the alignment assembly during preparation of the ankle joint.

10. The instrument kit of claim 9, wherein the tibial trial further comprises one or more guide wire holes, wherein the guide wire holes are configured to receive a guide wire therethrough to secure the tibial trial to the tibia.

11 . The instrument kit of claim 9, wherein the reamer assembly, the flexible drill assembly, and/or the guide wire assembly are configured to be releasably attached to the alignment assembly.

12. A flexible drill assembly for forming a cavity within a tibia of a patient for receiving a tibial component of an ankle prosthesis therein, the flexible drill assembly comprising: a drill guide; a flexible drill bit; and a guide wire; wherein the drill guide is in operative contact with the tibia, and the flexible drill bit is operatively positioned within the drill guide and about a guide wire inserted within the tibia, such that the flexible drill bit is operable to form a cavity within the tibia for receiving a tibial component of an ankle prosthesis by entering the tibia from the distal end without affecting an anterior surface of the tibia, a posterior surf ace of the tibia, or the proximal end of the tibia.

13. The flexible drill assembly of claim 12, further comprising a drill.

14. The flexible drill assembly of claim 12, wherein the flexible drill bit is cannulated to allow for passage of the flexible drill bit over the guide wire.

15. The flexible drill assembly of claim 12, wherein the guide wire is a k-wire.

16. The flexible drill assembly of claim 12, wherein a length of the cavity is greater than 20 mm, such as up to 45 mm.

17. The flexible drill assembly of claim 12, wherein the drill guide comprises: a body portion comprising a first sidewall and a second sidewall defining a gap therebetween for receiving the flexible drill bit therethrough.

18. The flexible drill assembly of claim 12, further comprising an upper protrusion configured to be received within a reciprocal channel of an alignment tool positioned within a gap defined between the tibia of the patient and the talus.

19. A method for preparing a tibia of a patient to receive a tibial component of an ankle prosthesis, the method comprising: resecting a distal end of the tibia to form an access point; positioning a reamer assembly within the access point; forming a first cavity in the tibia using the reamer assembly; positioning a guide wire assembly within the access point and first cavity; advancing a guide wire within the tibia along a central axis thereof; positioning a flexible drill assembly within the access point and the first cavity, around the guide wire positioned within the tibia; and forming a second cavity, using the flexible drill assembly, without affecting an anterior surface of the tibia, a posterior surface of the tibia, or a proximal end of the tibia.

20. The method of claim 19, further comprising the step of positioning an alignment assembly within the access point prior to positioning the reamer assembly, wherein the alignment assembly is retained within the access point for the duration of the method.

21. The method of claim 19, further comprising the step of implanting a tibial component of an ankle prosthesis within the second cavity.

22. A method of forming a cavity within a tibia of a patient for receiving a tibial component of an ankle prosthesis, the method comprising: forming a cavity within the tibia using a flexible drill assembly, wherein the cavity is formed without affecting an anterior surface of the tibia, a posterior surface of the tibia, or the proximal end of the tibia.