Femoral Head Arthroplasty System

Abstract

The femoral head arthroplasty system can include a femoral prosthesis including a mounting plate having a first side and an opposing second side. An adapter is extendable from the second side of the mounting plate. An implant body is extendable from the first side of the mounting plate. The implant body is extendable a distance of no more than 90 mm from the mounting plate. The femoral head arthroplasty system can further include a femoral head replacement device having a generally spherical surface and including a recess shaped to complementarily receive the adapter of the femoral prosthesis.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 860,549, filed June 12, 2019, the entire contents of which are incorporated by reference herein.

[0002] The disclosed invention relates to hip joint implants, and more particularly, to a system for securing a femoral head replacement device to a subject's femur. [Background technology]

[0003] Conventional hip implants are inserted into approximately 5-6 inches of the femur. Use of such conventional hip implants requires the patient to resect a significant amount of bone, which may not be desirable. A need exists for a hip implant system that does not require the resection of such a significant amount of bone. Summary of the Invention

[0004] In various aspects, a femoral head arthroplasty system is described herein. The femoral head arthroplasty system can include a femoral prosthesis. The femoral prosthesis can include a mounting plate having a first side and an opposing second side, an adapter extending from the second side of the mounting plate, and an implant body extending from the first side of the mounting plate. The implant body can extend from the mounting plate a distance not greater than 90 mm. The femoral head replacement device can have a generally spherical surface and can include a recess shaped to complementarily receive the adapter of the femoral prosthesis.

[0005] The femoral head arthroplasty system can include a femoral prosthesis. The femoral prosthesis can include a mounting plate having a first side and an opposing second side, an adapter extending from the second side of the mounting plate, and an implant body extending from the first side of the mounting plate, a distal end of the implant body having a planar surface that is generally parallel to the mounting plate. The femoral head replacement instrument can have a generally spherical surface and can include a recess shaped to complementarily receive the adapter of the femoral prosthesis.

[0006] The femoral head arthroplasty system can include a femoral prosthesis. The femoral prosthesis can include a mounting plate having a first side and an opposing second side. An implant body can extend from the first side of the mounting plate. The implant body can extend from the mounting plate a distance not greater than 90 mm. The mounting plate and the implant body can cooperate to define a recess. The femoral head replacement instrument has a generally spherical portion and an adaptor extending distally from the generally spherical portion. The adaptor can be configured to be complementarily received within the recess of the femoral prosthesis.

[0007] The implant body can include at least one radially extending spline.

[0008] The implant body can include a plurality of radially extending splines.

[0009] The implant body can include a generally cylindrical portion.

[0010] The implant body can define a semi-cylindrical surface.

[0011] The implant body can include a mounting bracket, and the mounting plate can define at least one opening configured to receive the mounting bracket.

[0012] The mounting bracket may include at least one screw.

[0013] The femoral prosthesis may comprise a porous or textured metal.

[0014] The porous or textured metal can be at least one metal selected from the group consisting of cobalt chromium, titanium, and tantalum.

[0015] The femoral prosthesis may include a coating.

[0016] The coating may be selected from the group consisting of hydroxyapatite, titanium oxide, titanium nitride, zirconium oxide, and pyrolytic carbon.

[0017] The coating can be configured to promote bone ingrowth or overgrowth.

[0018] The diameter of at least a portion of the implant body can range from about 10 mm to about 18 mm.

[0019] The implant body may have a variable outer diameter.

[0020] The adapter may have a Morse taper.

[0021] The femoral head replacement device may be angularly offset from the femoral prosthesis.

[0022] The method may include forming a preparation site in the femur and implanting a femoral head arthroplasty system such that an implant body is received in the preparation site, the preparation site extending a distance not greater than 30 mm distal to the lesser trochanter of the femur.

[0023] The mounting plate may have a major dimension that is equal to or greater than a major radial dimension of the femur. The mounting plate may be abuttable against the cortical bone at the cut proximal end of the femur.

[0024] The kit may include a femoral prosthesis including a mounting plate having a first side and an opposing second side, an adapter extending from the second side of the mounting plate, and an implant body extending from the first side of the mounting plate, the implant body extending a distance not greater than 90 mm from the mounting plate. The kit may further include a plurality of femoral head replacement devices, each having a generally spherical surface and including a recess shaped to complementarily receive the adapter of the femoral prosthesis, each femoral head replacement device of the plurality of femoral head replacement devices being a different size or material than every other femoral head replacement device of the plurality of femoral head replacement devices.

[0025] Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

[0026] These and other features of the preferred embodiments of the present invention will become apparent from the following detailed description, which is set forth in the accompanying drawings. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a side view of a femoral prosthesis of a femoral head arthroplasty system according to an embodiment disclosed herein. [Diagram 2] FIG. 2 is a side view of the femoral prosthesis of FIG. 1 with dimensions for one exemplary embodiment. [Diagram 3] FIG. 3 is a front view of the femoral prosthesis of FIG. [Figure 4] FIG. 4 is a front view of the femoral prosthesis of FIG. 3 with dimensions for one exemplary embodiment. [Diagram 5] FIG. 5 is a rear view of the femoral prosthesis of FIG. [Figure 6]FIG. 6 is a rear view of the femoral prosthesis of FIG. 5 with dimensions for one exemplary embodiment. [Figure 7] 7 is a side view of a femoral head replacement instrument of a femoral head arthroplasty system for use with the femoral prosthesis of FIG. 1. FIG. [Figure 8] FIG. 8 is a side view of another embodiment of a femoral head arthroplasty system. [Figure 9] FIG. 9 is a partial cutaway view of a femoral head arthroplasty system installed within a femur. [Figure 10] FIG. 10 is a posterior perspective view of an exemplary femoral prosthesis according to an embodiment disclosed herein. [Figure 11] FIG. 11 is a front perspective view of the exemplary femoral prosthesis of FIG. [Figure 12] FIG. 12 is a front view of the exemplary femoral prosthesis of FIG. [Figure 13] FIG. 13 is a top view of the exemplary femoral prosthesis of FIG. [Figure 14] FIG. 14 is a side view of the exemplary femoral prosthesis of FIG. [Figure 15] FIG. 15 is a perspective view of an exemplary femoral prosthesis according to an embodiment disclosed herein. [Figure 16] FIG. 16 is a cross-sectional view of the exemplary femoral prosthesis of FIG. [Figure 17] FIG. 17 is a side view of a fixation screw for use in a femoral prosthesis. [Figure 18] 18 is a first end view of the fixation screw of FIG. 17. FIG. [Figure 19] FIG. 19 is a cross-sectional view of the screw in the plane AA of FIG. [Figure 20] FIG. 20 is a detailed view of a cross section of the screw within circle B in FIG. [Figure 21] FIG. 21 is a detailed view of a cross section of the thread within circle C in FIG. [Figure 22] 22 is a second end view of the fixation screw of FIG. 17. FIG.

[0028] It should be understood that any dimensions or other measurements indicated in the drawings are merely exemplary and that other dimensions and measurements are contemplated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention will be described more fully below with reference to the accompanying drawings, which show some, but not all, embodiments of the present invention. Indeed, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments described herein, but rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Identical reference numbers refer to the same elements throughout. It is understood that the present invention is not limited to the specific methods and protocols described, as these may vary. It is further understood that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the scope of the present invention.

[0030] Many variations and other embodiments of the invention described herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings set forth in the foregoing descriptions and the associated drawings. It is to be understood, therefore, that the invention is not limited to the specific embodiments disclosed, and that variations and other embodiments are intended to be included within the scope of the appended claims. Although certain terms are used herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0031] As used herein, the singular articles "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, use of the term "a screw" may refer to one or more of such screws, etc.

[0032] All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless clearly defined otherwise.

[0033] As used herein, the term "optional" or "optionally" means that the event or circumstance described thereafter may or may not occur, and that the description includes both instances with and without the occurrence of the event or circumstance.

[0034] As used herein, the term "at least one of" is intended to be synonymous with "one or more of." For example, "at least one of A, B, and C" expressly includes A only, B only, C only, and combinations of each.

[0035] As used herein, the word "or" means any one part of a particular list, and also includes any combination of parts of that list.

[0036] Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when numerical values ​​are expressed as approximations, using the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that each endpoint of the range is significant both relative to the other endpoint, and independent of the other endpoint. Optionally, in some embodiments, when numerical values ​​are approximated by using the antecedent "about," it is contemplated that values ​​within up to 15%, up to 10%, up to 5%, or up to 1% (either above or below) of the specified numerical value may be included within the range of these embodiments. Similarly, in some embodiments, when numerical values ​​or characteristics are approximated by using the antecedent "approximately," "approximately," it is contemplated that values ​​within up to 15%, up to 10%, up to 5%, or up to 1% (either above or below) of the specified numerical value may be included within the range of these embodiments.

[0037] As used herein, the term "patient" may refer to a human or animal receiving an implant as further disclosed herein. In an exemplary embodiment, the patient may be a human who has been determined to be in need of receiving an implant as disclosed herein.

[0038] It will be understood that no method described herein is intended to be construed as requiring that its steps be performed in a particular order unless expressly stated otherwise. Thus, unless a method claim actually recites the order in which its steps follow, or unless otherwise expressly stated in the claim or description that the steps are limited to a particular order, no order is intended to be inferred in any respect. This applies to any possible implicit basis for interpretation, including questions of logic regarding the sequencing of steps or action flow, obvious meanings derived from grammatical construction or punctuation, and the number or type of aspects described herein.

[0039] The following description provides specific details to be fully understood. However, those skilled in the art will appreciate that the devices, systems, and related methods using the devices can be implemented and used without utilizing these specific details. In fact, the devices, systems, and related methods can be implemented by modifying the illustrated devices, systems, and related methods, and can be used with any other devices and techniques conventionally used in the industry.

[0040] Disclosed herein, in various aspects, and with reference to FIG. 1, is a femoral prosthesis 100 of a femoral head arthroplasty system. The femoral prosthesis 100 can include a mounting plate 110 having a first side 112 and an opposing second side 114. The mounting plate 110 can have a flat or substantially flat side and a thickness 502 of about 3 to about 7 mm (e.g., about 5 mm) in a first dimension (measured along a first axis 302) perpendicular to the surface of the first side. The mounting plate 110 can extend in a second dimension (measured along a second axis 304) by about 25 to about 40 mm (e.g., about 34 mm) and a length 504 can extend in a third dimension (measured along a third axis 306) by about 16 to about 25 mm (e.g., about 22 mm). The mounting plate 110 of the femoral prosthesis can have a major dimension that is greater than a major radial dimension of the patient's femur such that the mounting plate abuts the outer radial wall of the femur when implanted within the femur. A pair of upper corners can define a radius r1 (optionally about 2 mm), and the bottom of the mounting plate 110 can define continuous arcuate sides (optionally having a radius of 11 mm, or about half the width of the mounting plate measured along the third axis 306).

[0041] The mounting plate 110 can define one or more through holes 120 (e.g., a pair as shown) that can receive mounting hardware for mounting the femoral prosthesis to a patient. The holes 122 can have a respective diameter d5 (optionally ranging from about 4 mm to about 10 mm, or more preferably a diameter of about 7 mm). In some embodiments, the holes 122 can be spaced apart from each side edge of the mounting plate by a distance 526 (e.g., at least 1 mm, e.g., 1 to 4 mm, or more preferably, about 2 mm). The pair of through holes 120 can optionally define internal threads 122 for receiving the external threads of a mounting screw therein (see also FIGS. 15 and 16). In some optional embodiments, the pair of through holes 120 can be centered along a third axis 306 such that the femoral prosthesis extends in first and third dimensions (including axes 302, 306) and is symmetrical about a plane intersecting the femoral prosthesis 100. Although the embodiments described herein include features for screw attachment, in further embodiments, other attachment means such as wire, sutures, or cables can be used.

[0042] The implant body 130 can extend from the first side 112 of the mounting plate 110. The implant body 130 can be positioned below (i.e., offset in a second dimension (along the second axis 304) from) the pair of through holes 120. The implant body 130 can include a first cylindrical or generally cylindrical projection 132 extending perpendicular to the plane of the first side 112 of the mounting plate. The first generally cylindrical projection 132 can extend from the first side 112 of the mounting plate along a first axis 134 by less than 90 and more than 20 mm, and optionally by less than 75 and more than 30 mm, or between 35 and 60 mm (e.g., about 40 mm or about 45 mm). The first generally cylindrical projection 132 can optionally have a diameter d1 between about 10 and about 18 mm (e.g., about 14 mm). The distal end of the first generally cylindrical projection 132 (i.e., the end furthest from the mounting plate 110) may have an arcuate end 136 extending a length 512 with a first dimension 302 ranging from about 3 mm to about 8 mm, or more preferably about 5 mm. The distal end of the first generally cylindrical projection 132 optionally has a flat surface 138 that is generally parallel to the mounting plate. The first generally cylindrical projection 132 can be spaced from the bottom of the mounting plate 110, for example, about 2 mm. The first axis 134 of the first generally cylindrical projection 132 can optionally be spaced from the bottom of the mounting plate by a distance 530 (e.g., optionally about 7 mm to about 12 mm, or about 9 mm). In some optional aspects, the first generally cylindrical projection 132 can be spaced a distance 506 (eg, optionally between about 1 mm and about 4 mm, or about 2 mm) from the lower end of the mounting plate.

[0043] The implant body 130 may further include a second cylindrical or generally cylindrical projection 150 extending along a second axis 152 that is parallel to the first axis 134. The second axis 152 may optionally be perpendicular to the first axis 134. The second generally cylindrical portion 150 may extend a length 508 from the first side 112 of the mounting plate 110 of about 10 to about 40 mm (e.g., about 10 mm to about 20 mm, or about 15 mm). Thus, the second generally cylindrical portion 150 may have an end facing the mounting plate 110 that is a length 516 (e.g., about 25 mm to about 35 mm, or about 30 mm) from the end of the first generally cylindrical portion 130 that faces the mounting plate. The first and second axes 134, 152 can be spaced apart by less than the sum of the respective radii of the first and second generally cylindrical portions such that the second generally cylindrical projection 150 overlaps the first generally cylindrical projection 132. Thus, in a cross section perpendicular to the first axis 134, the overlapping first and second generally cylindrical projections 132, 150 can have a figure-eight shape. The second axis 152 can optionally extend along an upper end of the first generally cylindrical projection 132. The second axis 152 can be spaced apart from a top of the mounting plate by a distance 532 (e.g., optionally about 15 mm to about 20 mm, or about 18 mm) and from a bottom of the mounting plate by a distance 534 (e.g., optionally about 13 mm to about 18 mm, or about 16 mm). That is, the second axis 152 can be spaced from the first axis by the radius of the first generally cylindrical projection 132. The second generally cylindrical projection 150 can have a radius r3 of about 5 to about 9 mm (e.g., about 7 mm). The first and second generally cylindrical projections 132, 150 can cooperate to provide a rectangular cross-section to prevent the implant body 130 from rotating. Furthermore, the combined cross-sectional shape (e.g., a figure-of-eight shape) of the first and second generally cylindrical projections can cooperate with the bone preparation site to facilitate creation by the surgeon. In further embodiments, the implant body 130 can have a variety of other cross-sectional side profiles in a plane perpendicular to the longitudinal dimension of the implant body, including generally cylindrical, elliptical, polygonal (e.g., square or rectangular) or rectangular sides.

[0044] The implant body 130 can optionally extend from the mounting plate a distance of not more than 90 mm, or not more than 75 mm, or not more than 60 mm, or not more than 50 mm, or not more than 45 mm. As further disclosed herein, it is contemplated that the minimum length of the implant body 130 can reduce the amount of the subject's natural bone that must be resected to accommodate the implant body.

[0045] The adaptor 160 can extend from the second side 114 of the mounting plate 110 and can be oriented perpendicular or nearly perpendicular thereto. The adaptor 160 can optionally have a central axis 161 that is collinear with the second axis 152. Thus, the adaptor 160 can be offset axially upward (i.e., above) from the axis 134 of the first generally cylindrical projection 132. In this manner, for some patients, the femoral head attached to the adaptor 160 can most accurately replicate the normal anatomy of the patient. In further embodiments, the adaptor can have an axis that is offset from the axis 152. The adaptor 160 can optionally be axially aligned with the axis 134 in some such embodiments. The adaptor 160 can include a frusto-conical portion 162 that mounts to the mounting plate 110 via a neck portion 164. The neck portion can have a length 514 of about 3 mm to about 7 mm, or about 5 mm. The frusto-conical portion 162 can be tapered from a proximal end 166 (away from the mounting plate 110) to a distal end 168. The frusto-conical portion 162 can optionally have a Morse taper. The proximal end 166 can optionally have a diameter d2 of about 12 to about 16 mm (e.g., about 14 mm) and the distal end 168 can optionally have a diameter d3 of about 10 to about 14 mm (e.g., about 12 mm). The frusto-conical portion 162 can extend axially a length 510 from the proximal end 166 to the distal end 168 of about 10 to about 18 mm (e.g., about 14 mm). In some embodiments, the central axis of the adapter can be spaced a length 520 (optionally about 15 mm to about 20 mm, or about 18 mm) from the top of the mounting plate and a length 522 (optionally about 13 mm to about 18 mm, or about 16 mm) from the bottom of the mounting plate. The most radial surface of the adapter can be spaced a distance 524 (optionally about 3 mm to about 6 mm, or about 4 mm) from each opposing side edge of the mounting plate in the third dimension 306. Optionally, at least a portion of the circumferential surface of the frusto-conical portion can include an orientation that can improve frictional contact between the adapter 160 and the femoral head replacement device.In some optional embodiments, a helical groove having a pitch of 0.5 mm can define the orientation.

[0046] The neck portion 164 of the adaptor 160 may have a cross-section that varies along an axis within the arcuate side. The neck portion 164 may have a minimum diameter d4 at a midpoint along its axis, which in some embodiments may be about 12 mm. The opposing ends of the neck portion 164 may each have a diameter d2 of about 14 mm. Thus, the minimum diameter may be about 2 mm less than the maximum diameter of the neck portion 154. The narrowed diameter of the neck portion may provide a location for gripping the femoral prosthesis during implantation and removal of the femoral prosthesis.

[0047] Although the adapter 160 is shown extending parallel to the implant body 130, in further embodiments, the adapter 160 can be extended at various angles relative to the implant body 130 to change the varus / valgus angle of the femoral head relative to the longitudinal dimension of the femur.

[0048] Referring to FIG. 7, the adaptor 160 can receive a femoral head replacement instrument 200. The femoral head replacement instrument 200 can have a shape that cooperates with the acetabulum of the patient's pelvis or an artificial acetabulum. In some embodiments, the femoral head replacement instrument 200 can have a shape of a natural femoral head. The femoral head replacement instrument 200 can have a generally spherical side. The femoral head replacement instrument 200 can define a recess 210. The recess 210 can have a shape that is complementary to the adapter 160 (FIG. 1) of the femoral prosthesis 100 (FIG. 1). For example, the recess 210 can have a frusto-conical side. The prosthesis 200 can optionally be a conventional component known to those skilled in the art.

[0049] The femoral prosthesis 100 can be coupled to the femoral head replacement instrument 200 to create a femoral head arthroplasty system 250. In some embodiments, the femoral prosthesis 100 and the femoral head replacement instrument 200 can be coupled at any time, while in further embodiments, the pair can be coupled via non-permanent means. The adapter 160 and the femoral head replacement instrument 200 can have an interference fit (e.g., with a Morse taper) such that the respective components are in frictional contact with one another. As described above, at least one of the adapter 160 and the femoral head replacement instrument 200 can optionally have an orientation (i.e., a surface orientation) to improve the contact between the respective components.

[0050] 8, in a further embodiment, a femoral head replacement device 200' can include a generally spherical portion 202' and an adaptor 160' extending distally from the generally spherical portion 202'. The femoral prosthesis 100' can include a recess 210' and can otherwise have the same shape and dimensions as the femoral prosthesis 100 (FIG. 1). The adaptor 160' and recess 210' are shown as frusto-conical projections, but can have similar profiles to the adaptor 160 (FIG. 1) and recess 210 (FIG. 7), respectively, or any other adaptor profile known to one of ordinary skill in the art.

[0051] In some embodiments, the femoral prosthesis can include at least one radially extending spline 180, or, as shown, a plurality of radially extending splines 180. The radially extending splines 180 can provide a surface against which bone can grow, in addition to preventing the femoral prosthesis from rotating about its axis of extension.

[0052] The femoral prosthesis 100 and / or femoral head replacement device 200 can comprise a variety of materials known to those skilled in the art, such as, for example, porous, coated titanium, ceramics, tantalum, cobalt chromium alloys, or various other porous metals. The materials can be porous or textured to allow for bone ingrowth or overgrowth. The materials can be strong enough to withstand the weight of a patient without fracturing.

[0053] The femoral prosthesis 100 and / or femoral head replacement device 200 may include a coating. The coating may comprise one or more of the following: hydroxyapatite, titanium oxide, titanium nitride, zirconium oxide, and pyrolytic carbon. In further embodiments, the coating may include gold, ceramics, polymers (e.g., ultra-high molecular weight polyethylene), diamond-like carbon (DLC) coatings, zirconium oxide, titanium nitride, or various other coatings known to those skilled in the art. The coating may optionally be low friction and may optionally be hydrophobic.

[0054] 10-14, in some embodiments, the implant body 130 of the prosthesis 100 can have an elongated side in a second dimension (along the second axis 304). That is, in a cross section perpendicular to the second axis 304, the implant body 130 can have a major dimension measured along the second axis 304 and a minor dimension measured along a third axis 306. For example, the implant body 130 can define two semi-cylindrical surfaces 190 spaced apart along the second axis 304 and connected via a planar surface 192. This or another non-axisymmetric side surface can inhibit rotation of the implant body relative to the femur. In some embodiments, the implant body can have a major dimension measured along the second axis 304 of 18-25 mm (e.g., about 21 mm) and a minor dimension measured along the third axis 306 of 12-18 mm (e.g., about 14 mm).

[0055] In some optional aspects, the centerline 194 of the implant body (i.e., a line extending through the center of gravity of the cross-section in a plane perpendicular to the first dimension (first axis 302)) can be collinear with the central axis 161 of the adaptor 160. In further optional aspects, as shown in Figures 15 and 16, the centerline 194 can be offset from the central axis 161 of the adaptor 160 (optionally offset from the central axis 161 in a second dimension (relative to the second axis 304)).

[0056] In some optional aspects, the distal end of the implant body 130 can optionally have a planar surface 138 that is parallel or approximately parallel to the mounting plate. In further aspects, it is envisioned that the distal end of the implant body can define a circular rectangular surface 139 or other non-planar surface that extends parallel to the mounting plate. For example, the implant body 130 can define first and second radii 141 (optionally spherical) that are spaced apart from one another along the second dimension 304 (and are measured in a plane that includes the first and second axes).

[0057] In some embodiments, the centerline 194 of the implant body can extend along the entire length of the implant body, perpendicular to the mounting plate 110. For example, in any plane that intersects the implant body and is perpendicular to the first axis 302, a center point (which may optionally correspond to a center of mass) of the portion of the implant body in that plane is intersected by the centerline 194. In further embodiments, it is contemplated that the device can be symmetric about a plane that is perpendicular to the second dimension 304 and intersects the implant body (and thus includes the centerline 194). Optionally, in still further embodiments, it is contemplated that the implant body can be symmetric about both (a) a first plane that is perpendicular to the second dimension 304 and intersects the implant body, and (b) a second plane that is perpendicular to the third dimension 306 and intersects the implant body. It is contemplated that the above-described configurations can advantageously provide balance and force transmission characteristics while minimizing the amount of bone removed from the patient to accommodate the implant body by avoiding the need to provide an angled or asymmetrical implant body (e.g., where the implant body is required to anteriorly suture deeper into the native bone).

[0058] With reference to FIGS. 10-14, it is further envisioned that in some embodiments, neck portion 164 may have a constant diameter (rather than the constricted diameter shown in FIG. 1) to increase the strength of the prosthesis.

[0059] 17-22, the fixation screw 240 may have a head 241 defining a first thread (or threads) 242 and a body 243 defining a second thread (or threads) 244. Optionally, the head of the screw may be tapered. Thus, the hole 120 (FIG. 16) may be correspondingly tapered. The fixation screw may include one or more (e.g., optionally, three equally spaced circumferentially) self-tapping features 246 for tapping the bone during insertion of the screw. The fixation screw may include one or more (e.g., optionally, three equally spaced circumferentially) self-tapping features 247 for tapping the bone during removal of the screw. It should be understood that the dimensions (in mm) shown in the figures are optional aspects.

[0060] It is further envisioned that the prosthesis may be fixable to the femur in addition to or as an alternative to bone ingrowth and / or overgrowth and / or cement fixation.

[0061] The kit may include a femoral prosthesis 100 and a plurality of femoral head replacement devices 200. Each of the femoral head replacement devices 200 may differ from the other replacement devices in at least one of size or material.

[0062] With reference to FIG. 9, a medical practitioner (e.g., an orthopedic surgeon) can form a preparation site in the femur 400. For example, the medical practitioner can resect a portion of the patient's natural femoral head. The surgeon can optionally use a patient-specific cutting guide that identifies the optimal location and angle for resecting the femoral head. According to one embodiment, the cutting guide can include a frame that defines a slot for guiding a cutting saw. The cutting guide can be temporarily fixed to the femur using pins or screws and then detached from the femur after cutting. The surgeon can drill / reamer a pair of overlapping holes to receive the first and second cylindrical portions 132, 150. In a further aspect, the overlapping holes can be further drilled to provide an opening for receiving the implant body 130 (e.g., for the embodiment shown in FIGS. 10-14). The preparation site can be located further proximally along the neck of the femur (towards the natural femoral head) than a conventional femoral head preparation site for hip joint replacement. The preparation site can optionally extend no more than 30 mm distal to the lesser trochanter 402 of the femur 400 (i.e., past the lesser trochanter along the longitudinal axis of the femoral shaft towards the patient's foot). The medical practitioner can then implant the femoral prosthesis such that the implant body is received within the preparation site. The femoral prosthesis can be inserted such that the mounting plate abuts the upper end of the femur. The medical practitioner can drill into the patient's bone to receive the screws or other fasteners. The screws 240 or other fasteners can be used to secure the femoral prosthesis in place. The surgeon can optionally drill into the femur to receive the screws 240. A femoral head replacement instrument can then be attached to the femoral prosthesis.

[0063] In comparison to conventional implants, the embodiments disclosed herein allow for hip implants that require less bone resection, i.e., less bone can be resected, leaving a portion of the femoral neck available for extension of the femoral prosthesis. The disclosed embodiments can reduce bleeding during surgery and facilitate possible insertion into the procedure, especially in anterior approach procedures. The disclosed embodiments can be associated with fewer incisions than conventional implants, facilitating revision surgery, if necessary.

[0064] Exemplary embodiments In view of the described products, systems, and methods and variations thereof, certain more specifically described aspects of the invention are described herein below, however, these specifically recited aspects should not be construed as having any limiting effect on any different claims that include different or more general subject matter described herein, nor should the "particular" aspects be limited in any way other than in the inherent meaning of the term as literally used herein.

[0065] Aspect 1: A femoral head arthroplasty system comprising: a femoral prosthesis comprising a mounting plate having a first side and an opposing second side, an adapter extending from the second side of the mounting plate, and an implant body extending from the first side of the mounting plate, the implant body extending a distance not greater than 90 mm from the mounting plate; and a femoral head replacement device having a generally spherical surface and including a recess shaped to complementarily receive the adapter of the femoral prosthesis.

[0066] Aspect 2: A femoral head arthroplasty system comprising: a femoral prosthesis comprising: a mounting plate having a first side and an opposing second side, an adapter extending from the second side of the mounting plate, and an implant body extending from the first side of the mounting plate, the implant body having a distal end, the distal end of the implant body defining a surface extending generally parallel to the mounting plate; and a femoral head replacement device comprising a recess shaped to complementarily receive the adapter of the femoral prosthesis.

[0067] Aspect 3: A femoral head arthroplasty system comprising: a femoral prosthesis comprising: a mounting plate having a first side and an opposing second side; and an implant body extending from the first side of the mounting plate, the implant body extending a distance not greater than 90 mm from the mounting plate, the mounting plate and the implant body cooperating to define a recess; and a femoral head replacement instrument having a generally spherical portion and an adapter extending distally from the generally spherical portion, the adapter configured to be complementarily received within the recess of the femoral prosthesis.

[0068] Aspect 4: A femoral head arthroplasty system as described in Aspects 1-3, wherein the implant body comprises at least one radially extending spline.

[0069] Aspect 5: A femoral head arthroplasty system as described in Aspect 4, wherein the implant body comprises a plurality of radially extending splines.

[0070] Aspect 6: A femoral head arthroplasty system according to any one of Aspects 1 to 3, wherein the implant body forms an approximately semi-cylindrical surface.

[0071] Aspect 7: A femoral head arthroplasty system as described in any of Aspects 1 to 3, further comprising a mounting bracket, the mounting plate defining at least one opening configured to receive the mounting bracket.

[0072] Aspect 8: A femoral head arthroplasty system as described in Aspect 7, wherein the mounting bracket comprises at least one screw.

[0073] Aspect 9: A femoral head arthroplasty system according to any one of Aspects 1 to 3, wherein the femoral prosthesis comprises a porous or textured metal.

[0074] Aspect 10: The femoral head arthroplasty system described in Aspect 9, wherein the porous or textured metal is at least one metal selected from the group consisting of cobalt chromium, titanium, and tantalum.

[0075] Aspect 11: A femoral head arthroplasty system according to any one of Aspects 1 to 3, wherein the femoral prosthesis includes a coating.

[0076] Aspect 12: The femoral head arthroplasty system described in Aspect 11, wherein the coating is selected from the group consisting of hydroxyapatite, titanium oxide, titanium nitride, zirconium oxide, and pyrolytic carbon.

[0077] Aspect 13: A femoral head arthroplasty system as described in Aspect 11, wherein the coating is configured to promote bone ingrowth or surface growth.

[0078] Aspect 14: A femoral head arthroplasty system according to any one of Aspects 1 to 3, wherein the diameter of at least a portion of the implant body is in the range of about 10 mm to about 18 mm.

[0079] Aspect 15: A femoral head arthroplasty system according to any one of Aspects 1 to 3, wherein the implant body has a variable outer diameter.

[0080] Aspect 16: A femoral head arthroplasty system as described in Aspect 1 or 2, wherein the adapter has a Morse taper.

[0081] Aspect 17: A femoral head arthroplasty system as described in Aspect 1 or 2, wherein the femoral head replacement device is angularly offset from the femoral prosthesis.

[0082] Aspect 18: A method that may include forming a preparation site within the femur and implanting a femoral head arthroplasty system described in any one of aspects 1 to 17 so that an implant body is received within the preparation site, the preparation site extending a distance not greater than 30 mm distal to the lesser trochanter of the femur.

[0083] Aspect 19: The method of aspect 18, wherein the mounting plate has a major dimension that is greater than or equal to a major radial dimension of the femur, and the mounting plate abuts the cortical bone at the cut proximal end of the femur.

[0084] Aspect 20: A kit comprising: a femoral prosthesis comprising a mounting plate having a first side and an opposing second side, an adapter extending from the second side of the mounting plate, and an implant body extending from the first side of the mounting plate, the implant body extending a distance not greater than 90 mm from the mounting plate; and a plurality of femoral head replacement devices, each femoral head replacement device having a generally spherical surface and including a recess shaped to complementarily receive the adapter of the femoral prosthesis, each femoral head replacement device of the plurality of femoral head replacement devices being a different size or material than all other femoral head replacement devices of the plurality of femoral head replacement devices.

[0085] Although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, certain changes and modifications can be practiced within the scope of the appended claims.

Claims

1. 1. A femoral head arthroplasty system comprising:

1. A femoral prosthesis comprising: a mounting plate having a first side and an opposing second side, the first side of the mounting plate configured to abut a cut surface of a femur; an implant body extending from the first side of the mounting plate, the implant body extending from the mounting plate along a first axis a distance not greater than 90 mm, the implant body, in a cross-section taken in a plane perpendicular to the first axis, having a major cross-sectional dimension along a second axis and a minor cross-sectional dimension along a third axis different from the second axis, the minor cross-sectional dimension being smaller than the major cross-sectional dimension, the implant body being rectangular in cross-section taken in the plane perpendicular to the first axis, the implant body having a distal end, the implant body extending from the mounting plate along the first axis a distance not greater than 90 mm, a prosthesis for a femur comprising: an implant body defining a circumferential surface extending to a distal end thereof, the circumferential surface having two semi-cylindrical surfaces each having a length, the two semi-cylindrical surfaces being spaced apart along the second axis, and two parallel planar surfaces being spaced apart along the third axis and extending between and to the two semi-cylindrical surfaces throughout their respective lengths, the implant body having a centerline extending parallel to or collinear with the first axis throughout the entire length of the implant body; and a femoral head replacement instrument having a substantially spherical surface; A femoral head arthroplasty system, wherein one of the femoral prosthesis and the femoral head replacement device includes an adapter, and the other of the femoral prosthesis and the femoral head replacement device defines a recess having a complementary shape to receive the adapter.

2. The femoral head arthroplasty system of claim 1 , wherein the femoral prosthesis includes the adapter extending from a second side of the mounting plate.

3. 2. The femoral head arthroplasty system of claim 1, wherein the mounting plate and the implant body cooperate to define the recess, and the femoral head replacement instrument has an adapter and a generally spherical portion defining a generally spherical surface, the adapter extending distally from the generally spherical portion of the femoral head replacement instrument.

4. The femoral head arthroplasty system of claim 1 , wherein the implant body includes at least one radially extending spline.

5. The femoral head arthroplasty system of claim 4 , wherein the implant body includes a plurality of radially extending splines.

6. The femoral head arthroplasty system of claim 1 , further comprising a mounting bracket, said mounting plate defining at least one opening configured to receive said mounting bracket.

7. The femoral head arthroplasty system of claim 6 , wherein the mounting bracket comprises at least one screw.

8. 8. The femoral head arthroplasty system of claim 7, wherein the at least one screw has a head and a body, the head of the at least one screw defining a first thread, the body of the at least one screw defining a second thread, and the mounting plate defining a threaded hole configured to complementarily receive the first thread of the head of the at least one screw.

9. The femoral head arthroplasty system of claim 1 , wherein the femoral prosthesis comprises a porous or textured metal.

10. The femoral head arthroplasty system of claim 9 , wherein the porous or textured metal is at least one metal selected from the group consisting of cobalt chromium, titanium, and tantalum.

11. The femoral head arthroplasty system of claim 1 , wherein the femoral prosthesis includes a coating.

12. 12. The femoral head arthroplasty system of claim 11, wherein the coating is a coating selected from the group consisting of hydroxyapatite, titanium oxide, titanium nitride, zirconium oxide, and pyrolytic carbon.

13. The femoral head arthroplasty system of claim 11 , wherein the coating is configured to promote bone ingrowth or surface growth.

14. The femoral head arthroplasty system of claim 1 , wherein a diameter of at least a portion of the implant body ranges from about 10 mm to about 18 mm.

15. The femoral head arthroplasty system of claim 1 , wherein the adaptor has a Morse taper.

16. The femoral head arthroplasty system of claim 1 , wherein the femoral head replacement instrument is angularly offset from the femoral prosthesis.

17. The femoral head arthroplasty system of claim 1 , wherein the implant body has a distal end, the distal end of the implant body defining a surface that extends generally parallel to the mounting plate.

18. A femoral head arthroplasty system as described in claim 1, wherein the circumferential surface defined by the implant body continues continuously and uninterrupted from the mounting plate to the distal end.

19. A femoral head arthroplasty system as described in claim 1, wherein the first side of the mounting plate has a flat or approximately flat side, and the second side of the mounting plate has a flat or approximately flat side parallel to the first side.

20. A femoral head arthroplasty system as described in claim 1, wherein the distal end of the implant body defines a surface extending parallel to the first side of the mounting plate.

21. A femoral head arthroplasty system as described in claim 1, wherein the distal end of the implant body defines a circular surface.

22. A kit comprising:

1. A femoral prosthesis comprising: a mounting plate having a first side and an opposing second side, the first side of the mounting plate configured to abut a cut surface of a femur; an adapter extending from the second side of the mounting plate; an implant body extending from the first side of the mounting plate, the implant body extending from the mounting plate along a first axis a distance not greater than 90 mm, the implant body, in a cross-section taken in a plane perpendicular to the first axis, having a major cross-sectional dimension along a second axis and a minor cross-sectional dimension along a third axis different from the second axis, the minor cross-sectional dimension being smaller than the major cross-sectional dimension, the implant body being rectangular in cross-section taken in the plane perpendicular to the first axis, the implant body having a distal end, the implant body extending from the mounting plate along the first axis a distance not greater than 90 mm, a prosthesis for a femur comprising: an implant body defining a circumferential surface extending to a distal end thereof, the circumferential surface having two semi-cylindrical surfaces each having a length, the two semi-cylindrical surfaces being spaced apart along the second axis, and two parallel planar surfaces being spaced apart along the third axis and extending between and to the two semi-cylindrical surfaces throughout their respective lengths, the implant body having a centerline extending parallel to or collinear with the first axis throughout the entire length of the implant body; a plurality of femoral head replacement devices, each having a generally spherical surface and including a recess shaped to complementarily receive the adapter of the femoral prosthesis, each of the plurality of femoral head replacement devices being a different size or material than all other femoral head replacement devices of the plurality of femoral head replacement devices.

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