Improved glenoid implants

Abstract

Disclosed are various embodiments of improved glenoid implants that offer enhanced durable primary fixation to the bone. Also disclosed are some related surgical procedures. According to one embodiment, the glenoid implant can comprise a fixation screw and an articular body.

Description

IMPROVED GLENOID IMPLANTSFIELD OF DISCLOSURE

[0001] The present disclosure generally relates to glenoid implants for shoulder prosthesis.BACKGROUND

[0002] A shoulder prosthesis includes a glenoid implant intended to replace the glenoid cavity of the scapula and / or a humeral implant intended to replace the humeral head. The glenoid implant generally includes an articular body intended to articulate with the humeral head, and a fixation means to stabilize the articular body with respect to the scapula.

[0003] Currently, clinical literature shows a high rate of radiolucency around glenoid cemented, non-cemented, and hybrid components in long-term use of those glenoid implants. One issue is the potential for rocking of the implant when shoulder joint is subjected to daily living activities. Currently, cemented implants provide short- and mid-term fixation, but often can loosen over time. The current hybrid cemented-press fit implants show similar performance. Press fit implants historically show high loosening at mid- to long-term time points.

[0004] One of the challenges with press-fit glenoid implants is that it is difficult to reliably secure the implant to the bone, which is why hybrid cemented-press fit implants have increased in popularity. Adding a modular metal tray with screws is a solution that is used in many other joints, however in the shoulder there is often insufficient space for a modular tray. In addition, a modular connection between the metal tray and the bearing component may present a risk of unintended modular component separation, compared to a single piece implant.

[0005] Thus, improved glenoid implant design that offers enhanced and durable primary fixation to the bone is desired.SUMMARY

[0006] Disclosed are various embodiments of improved glenoid implants that offer enhanced durable primary fixation to the bone. According to one embodiment, the glenoid implant can comprise a fixation screw and an articular body. The fixation screw comprises a body having a proximal end, a distal end, a proximal portion near the proximal end, and a distal portion near the distal end. The articular body is configured for articulation with a humerus or a humeral implant,and comprises a concave articulation surface on one side of the articular body and a distal surface on opposite side of the articular body.

[0007] The proximal portion of the fixation screw is threaded with a first thread having a first thread pitch and the distal surface of the articular body comprises a protrusion configured with a threaded recess for threadedly engaging the proximal portion of the fixation screw. The distal portion of the fixation screw is threaded with a second thread having a second thread pitch for threading into a glenoid. The first thread pitch is smaller than the second thread pitch; and the first thread and the second thread are same handed.

[0008] Also disclosed is an improved bone anchor for anchoring into a glenoid. The anchor comprising: a hub that comprises: a bore for coupling with an anatomic glenoid articular component or a glenosphere; and at least two screw receiving portions attached to the hub by one or more arms extending outwardly from the hub, wherein each of the screw receiving portions include a hole for receiving a bone screw for anchoring the anchor to the glenoid, portions, wherein each of the screw receiving portions include a hole for receiving a bone screw for anchoring the anchor to the glenoid.

[0009] Also disclosed is an implant assembly kit for a glenoid. The kit can comprise: the bone anchor that comprises a hub that comprises: a bore for coupling with an anatomic glenoid articular component or a glenosphere; and at least two screw receiving portions attached to the hub by one or more arms extending outwardly from the hub, wherein each of the screw receiving portions include a hole for receiving a bone screw for anchoring the anchor to the glenoid, portions, wherein each of the screw receiving portions include a hole for receiving a bone screw for anchoring the anchor to the glenoid; at least one articular component that can be an anatomic glenoid articular component or a glenosphere. The anatomic glenoid articular component comprises: a concave surface configured to articulate with a humeral component; a second surface opposite from the concave surface; and a peg extending from the second surface configured to couple with the bore in the hub; the glenosphere comprises: an outer articulating surface; and a second surface opposite from the outer articulating surface; and an adapter for attaching the glenosphere to the anchor, wherein the adapter comprises: a first side configured to engage the glenosphere; and a second side opposite from the first side comprising a peg extending from the second side configured to couple with the bore in the hub.

[0010] Also disclosed is an implant that comprises: three bone screws, each comprising a threaded shaft and a screw head configured with a bearing component having convex bearing surface; and a body having three holes, each for receiving one of the three bone screws for anchoring the anchor to an articulating surface of a bone, wherein when the bone screws are inserted into the three holes and fully seated, the convex bearing surfaces of the three bone screws protrude from the three holes and form three-point contact bearing surface that can engage a complementary articulating component.

[0011] Also disclosed is a bone implant that comprises a bone screw having an elongated threaded body and a screw head that is configured with a bearing component having convex bearing surface. Three such bone screws can be used as an implant forming a three-point contact articulating bone surface. Such bone implant can be utilized on a glenoid.

[0012] Also disclosed is a method comprising: preparing an articulating surface of a bone; identifying three locations on the articulating surface for forming a three-point contact surface that replaces the articulating surface; drilling a pilot hole at each of the three locations; and threading a bone screw into each of the three pilot holes, wherein the bone screw comprises an elongated threaded body and a screw head that is configured with a bearing component having convex bearing surface.

[0013] Also disclosed is a glenoid implant that comprises: a disc-shaped baseplate that comprises: a generally circular bone-engaging surface; a generally circular second surface opposite the bone-engaging surface; a sidewall extending between the bone-engaging surface and the second surface; a post protruding from the bone-engaging surface and centrally located on the bone-engaging surface; and an articular component that is configured to engage the baseplate via the centrally located recess on the second surface of the baseplate, wherein the articular component can be an anatomic glenoid articular component or a reverse anatomic glenosphere, wherein the second surface comprises a centrally located recess for receiving and coupling with the articular component, wherein the recess is longitudinally aligned with the post protruding from the bone-engaging surface.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The various embodiments of the inventive glenoid implants of the present disclosure will be described in more detail in conjunction with the following drawing figures. Thestructures in the drawing figures are illustrated schematically and are not necessarily intended to show actual dimensions or relative scale.

[0015] FIGs. 1 A-1E show an example of improved anatomic glenoid implant configured for inlay application according to the present disclosure.

[0016] FIGs. 2A-2J show an example of a glenoid implant assembly according to another embodiment of the present disclosure.

[0017] FIGs. 3A-3C show more examples of glenoid implant assemblies according to other embodiments of the present disclosure.

[0018] FIG. 3D shows three bone screws implanted on a glenoid with their convex bearing surfaces protruding above the glenoid surface and forming a three-point contact articulating surface according to an embodiment of the present disclosure.

[0019] FIG. 3E shows an artificial humeral head component in an engaging position against the three-point contact articulating surface formed by the three convex bearing surfaces shown in FIG. 3D.

[0020] FIGs. 4A-4M show various examples of another convertible glenoid implant assembly.

[0021] FIGs. 5A-5J are illustrations showing an example of a procedure for implanting an anatomic configuration of the glenoid implant of FIGs. 4A-4L.

[0022] FIGs. 6A-6D are illustrations showing the method of converting the glenoid implant system of FIGs. 4A-4M from an anatomic configuration to a reverse configuration.DETAILED DESCRIPTION

[0023] This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. The drawing figures are not necessarily to scale and certain features may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as "horizontal," "vertical," "up," "down," "top" and "bottom" as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including "inwardly" versus "outwardly,""longitudinal" versus "lateral" and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as "connected" and "interconnected," refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. When only a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. The term "operatively connected" is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. In the claims, means-plus-function clauses, if used, are intended to cover the structures described, suggested, or rendered obvious by the written description or drawings for performing the recited function, including not only structural equivalents but also equivalent structures.

[0024] [Concept 1]

[0025] According to some embodiments, provided is an improved anatomic glenoid implant that utilizes bottom load screw that threads into a glenoid baseplate that forms a bone-engaging side of the baseplate. The opposite side of the baseplate comprises an articulating surface (z.e., the bearing surface) that is generally made of a durable low friction material such as polyethylene. In some embodiments, the polyethylene can be compression molded onto the baseplate thus forming an anatomic glenoid implant. In some embodiments, the articulating surface can be made of a high-modulus polyethylene (HMPE), ultra-high-molecular-weight polyethylene (UHMWPE), or any of the known polyethylenes.

[0026] Referring to FIGs. 1A-1E, an example of such glenoid implant 100 is disclosed. The implant 100 comprises a fixation screw 110, and an articular body 130. The fixation screw 110 comprises a body having a proximal end 111 (see FIG. 1C), a distal end 112, a proximal portion 111A near the proximal end 111, and a distal portion 112A near the distal end 112. For the purposes of discussion here with respect to the glenoid implant 100, the term “proximal” denotes being closer to the end of the implant 100 having the articular body 130 and the “distal” denotes being further away from the articular body 130 along the length of the fixation screw 110.

[0027] The articular body 130 is configured for articulation with a humerus or a humeral implant (not shown). The articular body 130 comprises a concave articulation surface 132 (i.e., the bearing surface) on one side of the articular body and a distal surface 134 on the bone-engaging side of the articular body 130. The distal surface 134 is the side opposite from the articulation surface 132.

[0028] The proximal portion 111 A of the fixation screw is threaded with a first screw thread HIT having a first thread pitch. The distal portion 112A of the fixation screw 110 is threaded with a second screw thread 112T having a second thread pitch for threading into a glenoid. The distal surface 134 of the articular body 130 comprises a protrusion 135 configured with a threaded recess 135R for threadedly engaging the proximal portion 111A of the fixation screw 110

[0029] The first thread pitch of the first screw thread HIT is smaller than the second thread pitch of the second screw thread 112T. The first screw thread and the second screw thread are same handed which allows the fixation screw and the articular body to be assembled together as a unit first. Then, the assembled glenoid implant 100 can be threaded onto the prepared glenoid.

[0030] In use, the glenoid implant 100 can be first assembled by threading the first screw thread HIT of the fixation screw 110 into the threaded recess 135R of the articular body 130 on the bone-engaging side of the baseplate. Then, the glenoid implant 100 can be threaded into a glenoid that has been prepared with a hole for receiving the glenoid implant 100. This threaded engagement with the bone is accomplished using the second screw thread 112T of the fixation screw 110

[0031] The hole in the glenoid can be prepared with a countersink to accommodate the protrusion 135 of the articular body 130 so that at least the protrusion 135 portion of the glenoid implant 100 sits below the prepared glenoid surface.

[0032] In some applications, the hole in the glenoid can be prepared to be large enough to allow the whole articular body 130 of the glenoid implant 100 to sit below the prepared glenoid surface as an inlay glenoid implant.

[0033] Referring to FIG. 1 A, the articular body 130 can comprise a polymer portion 133 that forms the concave articulation surface 132. The articular body 130 can comprise a base plate 136 that forms the distal surface 134 and the protrusion 135. The baseplate 136 can be made of a metal or a metal alloy. The polymer portion 133 and the baseplate 136 can be secured to eachother by any known means but in some embodiments, the polymer portion 133 can be compression molded onto the baseplate 136.

[0034] In some embodiments, at least some portions or all of the distal surface 134 of the articular body 130 and / or the protrusion 135 can comprise porous coated surface for promoting bone tissue in-growth when the glenoid implant is implanted in a glenoid. In the example shown in FIG. 1A, both the distal surface 134 and the protrusion 135 are coated with porous metal coating. In the example shown in FIG. IB, the distal surface 134 has a porous surface and the protrusion 135 has a non-porous surface. Some examples of such porous metallic material are TritaniumRby Stryker Corporation and ADAPTIS™ by Wright Medical Technology. Such embodiments allow initial fixation of the glenoid implant 100 achieved with the fixation screw 110 and long-term fixation achieved with the porous coating structure through bone tissue ingrowth.

[0035] In some embodiments, the distal surface 134 of the articular body 130 can comprise at least a portion that is a roughened surface (formed by grit blasting or mechanically engraving, for example) and bone cement can be used to bond the baseplate 130 to the bone.

[0036] The fixation screw 110 has a longitudinal axis that defines a longitudinal axis L of the glenoid implant and the distal surface 134 of the articular body 130 can be flat and extends orthogonal to the longitudinal axis of the glenoid implant.

[0037] The articular body 130 comprises a sidewall 130S that extends between the articulation surface 132 and the distal surface 134 and the sidewall 130S comprises two or more grooves 137 that extend from the articulation surface 132 to the distal surface 134. In other words, the grooves 137 are oriented generally parallel to the longitudinal axis L of the implant. The grooves 137 can be straight. The grooves 137 are provided to assist in turning the implant 100 to thread the fixation screw 110 into a complementary hole prepared in the glenoid. The grooves 137 can accommodate a pronged instrument that mates with the grooves 137 to grip the articular body 130. The implant 100 can be used in an onlay or an inlay application.

[0038] FIG. ID shows the straight-on view of the articulation surface 132 of the implant 100. The grooves 137 can be particularly useful in an inlay application in gripping the articular body 130 as the articular body 130 advances into a prepared recess in the glenoid bone. As the implant 100 is threaded into a prepared glenoid and the articular body 130 advances further into the glenoid, the final turns of the implant 100 can be accomplished by a pronged instrument thatengages the grooves 137 to grip the articular body 130. The number of grooves 137 provided on the articular body 130 can be any number as long as there are at least two and they are located radially symmetric so that the pronged instrument can rotate the articular body 130. Therefore, the symmetry in the positions of the grooves is helpful for this function of the pronged instrument.

[0039] The articular body 130 comprising the baseplate 136 and the polymer portion 133 can be circular in shape. Because the articular body 130 is threaded onto the glenoid bone, a rotationally symetric circular shape is beneficial as such shape provides consistent shape for the articulation surface 132 regardless of when the articular body 130 is fully seated in the glenoid during the threading procedure.

[0040] FIG. IE shows a sectional view of the articular body 130. The protrusion 135 forms a recess 135R that is treaded to receive the the thread HIT of the screw 110

[0041] [Concept 2]

[0042] Referring to FIGs. 2A-2H, disclosed is an embodiment of a new glenoid implant assemblies 200A and 200B. According to one embodiment, the implant assembly 200A shown in FIGs. 2A-2B comprises an anchor 210, and an anatomic glenoid articular component 220 for configuring the glenoid implant assembly into an anatomic implant. In use, the anchor 210 is configured to be secured to a glenoid bone first. Then, the anatomic glenoid articular component 220 is secured to the anchor 210.

[0043] According to another embodiment, the implant assembly 200B shown in FIGs. 2E-2H comprises an anchor 210, an adapter 240, and a glenosphere 230 as a humeral component for configuring the glenoid implant assembly into a reverse anatomic implant. In use, the anchor 210 is secured to a glenoid bone first. Then, the adapter 240 is attached to the anchor 210. Then, the glenosphere 230 gets attached to the adapter 240.

[0044] Referring to FIG. 2C, the anchor 210 comprises a hub 211, and at least two arms 215 extending outwardly from the hub 211, where each of the at least two arms terminate with one or more screw receiving portions 217. The anchor 210 is configured to provide a minimal volume of anchor material that gets imbedded into the glenoid bone. The configuration of the anchor 210 achieves this by providing a means for securing the anchor to the bone that comprises two or more screw receiving portions 217 that have minimum volume of material that allows securing the anchor 210 to the bone by bone screws 218. In the illustrated example, each of the screwreceiving portions 217 is a short cylindrical sleeve-like structure that captures the head of the bone screw 218. The anchor 210 also includes the hub 211 that is provided for attaching one of the articular components, the anatomic glenoid articular component 220 or the glenosphere 230, to the anchor 210. The hub 211 is also configured to provide a minimum volume of material that allows securing one of the articular components to the anchor 210. In the illustrated example, the hub 211 is a short cylindrical sleeve-like structure that receives one of the articular components and form a secure connection. This minimizes the amount of glenoid bone material that needs to be removed in preparing the glenoid to receive the anchor 210. Because glenoid is a relatively small bone structure, salvaging as much of the bone material as possible is generally beneficial in shoulder arthroplasty procedure.

[0045] Each of the screw receiving portions 217 is attached to the hub 211 by an arm 215. One arm 215 can connect at least one screw receiving portions 217 to the hub 211. In the illustrated example shown in FIG. 2C, where there are three screw receiving portions 217, one arm 215 connects one of the screw receiving portions 217 to the hub 211, and a second arm 215 connects the remaining two screw receiving portions 217 to the hub 211. The secone arm 215 has a bifurcated structure for connecting two screw receiving portions. In other embodiments, there can be multiple arms 215 with each arm connecting just one screw receiving portion 217 to the hub 211. One such example is shown in FIG. 2F. In the example shown in FIG. 2F, the anchor210 comprises three screw receiving portions 217. Each screw receiving portion 217 is attached to the hub 211 by one arm 215. The positions of the screw receiving portions 217 about the hub211 can be in any desired pattern. For example, in the example shown in FIG. 2F, the screw receiving portions 217 are located at radially symmetric positions about the hub 211. In other embodiments, the screw receiving portions can be located in positions that are not radially symmetric about the hub 211, as shown in FIG. 2C.

[0046] Each of the screw receiving portions 217 can be configured as a sleeve with a bore 217H extending through it for receiving a bone screw 218 for anchoring the anchor 210 to the glenoid. The bore 217H has an opening at each end. The opening 217h (see FIGs. 2E, 2E’) at the exit side of the bore 217H has a smaller diameter than the diameter of the head of the bone screw 218 so that the bone screw can secure the anchor 210 against the glenoid bone.

[0047] The exit side of the bore 217H is the side where the threaded shaft of the screw 218 extends through the bore 217H of a screw receiving portion 217 and gets threaded into theglenoid bone. FIG. 2A shows the surface of the glenoid bone represented by the dashed line B into which the anchor 210 is secured. As shown in FIG. 2E, which is a longitudinal cross-section view through one of the screw receiving portion 217, in some embodiments, the smaller hole 217h on the exit side of the bore 217H can be formed by an annular rim or a lip 217HR that extends inward. The annular rim 217HR captures the head of the bone screw 218 within the bore 217H. As shown in FIG. 2E’, in some embodiments, the inner wall of the bore 217H can be tapered to form the smaller hole 217h on the exit side.

[0048] The hub 211 also has a bore 212 for coupling with the anatomic glenoid articular component 220 or the glenosphere 230. In some embodiments, the bore 212 in the hub 211 can be tapered and the peg 225 on the anatomic articular component 220 can be correspondingly tapered (z.e., Morse taper) to engage the tapered bore to form a friction fit.

[0049] FIG. 2A shows the glenoid implant assembly 200A in an anatomic configuration with the anatomic articular component 220 attached to the anchor 210. FIG. 2B is an isometric view of the assembly 200A from the anchor side. FIG. 2C shows the anchor 210 with the bone screws 218 in place. FIG. 2D shows a side view of the anatomic articular component 220. The anatomic glenoid articular component 220 comprises a concave surface 222 configured to articulate with a humeral component (not shown), a second surface 223 opposite from the concave surface 222, and a peg 225 extending from the second surface 223 configured to couple with the bore 212 in the hub 211.

[0050] In some embodiments, the peg 225 on the anatomic articular component 220 can have a length such that a distal portion of the peg 225 extends out a distance through the hub 211 when fully coupled with the hub. This arrangement can be seen in FIGs. 2A and 2B. This allows the peg 225 to be inserted into a pre-drilled hole in the glenoid when the implant assembly 200 is installed onto a glenoid. The distal portion of the peg 225 that extends out through the hub 211 can be provided with fins 225F on its exterior surface. The fins 225F can hold a quantity of bone cement when the implant assembly 200 is affixed to the glenoid.

[0051] Referring to FIGs. 2G-2J, the glenosphere 230 of the glenoid implant assembly 200B comprises an outer articulating surface 230S, and a second surface opposite from the outer articulating surface 230S.

[0052] The adapter 240 comprises a first side 241 configured to engage the glenosphere 230, and a second side 242 opposite from the first side 241 comprising a peg 245 extending from the seconds side 242 configured to couple with the bore 212 in the hub 211.

[0053] In some embodiments, the anatomic articular component 220 can have a plurality of protrusions 226. Each of the protrusions 226 is aligned to fit into the hole 217H provided in the screw receiving portions 217 of the arms of the hub 211 when the anatomic articular component 220 engages the anchor 210 and prevent unwanted rotation of the anatomic articular component 220 with respect to the anchor 210. In some embodiments, the protrusions 226 could also be designed such that they fit into a modified screw head that helps keep the anatomic articular component locked in place not only rotationally but also axially. For example, the screw head and the protrusions 226 can be configured with shapes that can friction fit into each other or snap fit into each other.

[0054] For the reverse anatomic configuration, the adapter 240 functions as the intermediary structure that connects the glenosphere 230 and the anchor 210. The glenosphere 230 can be configured with a recess 232 that mates with the first side 241 of the adapter 240. In turn, the first side 241 can be provided with a complementary protrusion 246 that mates with the recess 232. In some embodiments, the sidewall of the recess 232 (z.e., the interior of the recess 232) and the sidewall of the protrusion 246 can be correspondingly tapered to form a friction fit.

[0055] Referring to FIG. 2H, within the recess 232 of the glenosphere 230, the glenosphere can be provided with a peg 235 that also mates with the first side 241 of the adapter 240 to provide additional fixation between the glenosphere 230 and the adapter.

[0056] At the adapter / anchor interface, the peg 245 on the adapter 240 mates with the bore 212 in the hub 211. The peg 245 and the bore 212 can be correspondingly tapered to engage each other and form a friction fit.

[0057] FIG. 21 shows the glenoid implant assembly 200B that is in a reverse anatomic configuration with the glenosphere 230 attached to the anchor 210 via the adapter 240. FIG. 2J shows a longitudinal cross-section view of the glenoid implant assembly 200B. The section is taken through the hub 211 of the anchor 210 and the peg 245 of the adapter 240.

[0058] In FIGs. 2A and 21, the dashed line B represents the surface of glenoid. Both glenoid implant assemblies 200A and 200B can be implanted so that the body of the anchor 210 sits below the surface of glenoid. The shape of the anchor 210 allows more bone preservationcompared to many conventional glenoid implant baseplates. Because the shape of the anchor 210 is not bulky, the preparation of the glenoid to receive the anchor 210 would require removal of minimal amount of bone material. Bone preparation could be done manually or by a robot to match the unique shape of the anchor 210.

[0059] According to the present disclosure, an implant assembly kit for a glenoid containing the anchor 210 is also disclosed. The kit comprises the anchor 210, at least one articular component that can be the anatomic glenoid articular component 220 or the glenosphere 230, and one adapter 240.

[0060] [Concept 3]

[0061] Referring to FIGs. 3 A and 3B, also disclosed is an implant that comprises an anchor that includes: three bone screws, each bone screw comprising a threaded shaft and a screw head configured with a bearing component having a convex bearing surface; and a body having three holes, each hole for receiving one of the three bone screws for anchoring the anchor to an articulating surface of a bone, wherein when the bone screws are inserted into the three holes and fully seated, the convex bearing surfaces of the three bone screws protrude from the three holes and form three-point contact bearing surface that can engage a complementary articulating component.

[0062] An example of such implant can be used as a glenoid implant in shoulder arthroplasty. Illustrated in FIGs. 3A-3B is and example of such glenoid implant assembly 200C that utilizes the anchor stmcture 210. In this embodiment of a glenoid implant assembly 200C, rather than the anchor structure 210 being attached to the anatomic articular component 220 or the glenosphere 230, a bone screw 218A that is configured with a bearing component 250 at the screw head is inserted into the bore 217H of each of the screw receiving portions 217 of the anchor 210. In this embodiment, the anchor 210 preferably has three screw receiving portions 217. Such a bone screw 218A is shown in FIG. 3B.

[0063] The bearing component 250 can be made of a medical grade durable high-modulus HMPE, UHMPE, or any of the known polyethylene and provides a convex bearing surface 251 at the screw head. In some embodiments, the bearing component 250 can be overmolded onto the head of the bone screw. In some embodiments, the head of the bone screw 218A can be configured with a cavity and the bearing component 250 can be pressfit into the cavity.

[0064] As shown in FIG. 3A, when the bone screws 218A are fully seated within the bores 217H, the convex bearing surface 251 protrudes from the screw receiving portions 217 and present the bearing surfaces 251. Thus, when the bone screws 218A are inserted into the three holes 217H and fully seated, the protruding convex bearing surfaces 251 of the three bone screws effectively form a three-point contact bearing surface for a complementary humeral articularing component.

[0065] When the glenoid implant assembly 200C is implanted in a glenoid and engages the corresponding humeral articulating component, which may be a natural humeral head or an artificial humeral head, the bearing surfaces 251 of the three bone screws 218A provide a three- point contact articulating surface that provides low friction. An example of this configuration can be seen in FIG. 3C where the three bone screws 218A are shown without the body of the anchor 210 and contacting an artificial humeral head HH.

[0066] In some embodiments, the bearing component 250 on the bone screws 281A can be offered in a variety of lengths. This will allow customizing the amount of protrusion of the connvex bearing surface 251 for each of the three bone screws 218A and adjust depending on the contour of the glenoid surface. Thus, in some situations, all three bearing components 250 in a given implant assembly 200C can have the same amount of protrusion and in other situations, they can be individually customized.

[0067] [Concept 4]

[0068] Referring to FIGs. 3B and 3C again, according to another aspect, the bone screws 218A that are configured with the bearing component 250 can be implanted directly into an articulating surface of a bone without the use of the anchor 210. An example is implanting the bone screws 218A into the glenoid surface. The glenoid surface may need to be reamed or otherwise prepared as necessary. Then, three locations for forming the three-point contact surface for the complementary humeral component are determined. Pilot holes are drilled at those three locations with appropriate countersink to accommodate the bearing component 250 portions of the bone screws 218A. Next, the three bone screws 218A are screwed into the pilot holes to form a new glenoid surface.

[0069] As noted above, in some embodiments, the amount of protrusion of the bearing component 250 for each of the three bone screws 218A can be customized to achieve the desired positions for the three points of contact.

[0070] This method of using three bone screws 218A configured with the bearing components 250 to form the three-point contact bearing surface at the glenoid would maximize preserving glenoid bone tissue. This configuration of using three bone screws 218A can also reduce the "rocking horse effect" seen in many glenoid implants since none of the contact points are connected to the others. This would reduce the chance of the implant loosening.

[0071] FIG. 3D shows three bone screws 218A implanted on a glenoid with their convex bearing surfaces 251 protruding above the glenoid surface and forming the three-point contact articulating surface. As an example, FIG. 3E shows an artificial humeral head HH component in an engaging position against the three-point contact glenoid surface formed by the three convex bearing surfaces 251.

[0072] [Concept 5]

[0073] Referring to FIGs. 4A-4M, also provided is another example of improved convertible glenoid implant assembly 300 that has a configuration that includes an inlay baseplate that sits below the glenoid articulation surface. This configuration can enhance fixation of the implant while reducing overall construct thickness.

[0074] The convertible glenoid implant assembly 300 comprises a circular disc-shaped baseplate 310, and an articular component 320. The disc-shaped baseplate 310 comprises a generally circular bone-engaging surface 311, a generally circular second surface 312 (see FIG. 4B) opposite the bone-engaging surface 311, a sidewall 313 extending between the bone-engaging surface 311 and the second surface 312, and a post 315 protruding from the bone-engaging surface 311 and centrally located on the bone-engaging surface 311.

[0075] The articular component 320 is configured to engage the baseplate 310 via the centrally located recess 312R on the second surface 312 of the baseplate 310. The articular component 320 can be an anatomic glenoid articular component 320A (See FIGs. 4A-4B) or a reverse anatomic glenosphere 320R (See FIGs. 4F-4H). The anatomic glenoid articular component 320A could be as depicted, i.e., polymer material compression molded on to a metallic taper. In some embodiments, the anatomic glenoid articular component 320A could also be an all metal component that would then articulate with a polymer head as a way of reducing overall construct thickness.

[0076] The second surface 312 can comprise a centrally located recess 312R (See FIG. 4C) for receiving and coupling with the articular component 320. The centrally located recess 312R is longitudinally aligned with the post 315 protruding from the bone-engaging surface 311.

[0077] Referring to FIG. 4E a straight on view of the second surface of the base plate according to the present disclosure, in some embodiments, the baseplate 310 can further comprise one or more screw receiving holes 312H peripherally located with respect to the post 315. Each of the screw receiving holes 312H is configured to receive a bone screw 318 from the second surface 312 side and holds the bone screw’s head.

[0078] In some embodiments, each of the one or more screw receiving holes 312H are configured to receive a bone screw 318 within a range of angular orientation. The bone screws 318 used in one implant assembly can have all same lengths or different lengths depending on the condition of the particular patient’s bone.

[0079] In some embodiments, the post 315 can be coated with a porous material that promotes bone tissue ingrown when implanted in a glenoid. Some examples of such porous metallic material are Tritanium® by Stryker Corporation and ADAPTIS™ by Wright Medical Technology.

[0080] In some embodiments, the baseplate 310 and the post 315 can be constructed as a monolithic structure.

[0081] Referring to FIG. 4K, in some embodiments, the post 315 can be configured to receive a modular extension component at the distal end of the post 315. For example, the post 315 can be configured to have its distal portion be modular or removable and replaceable with a number of different configurations. In the illustrated example in FIG. 4K, the distal portion of the post 315 can be provided as removable threaded screw shaft 315S or a removable post tip 315P. In the context of the glenoid implant assembly 300, distal portion refers to the portion of the post 315 that is furthest from the bone-engaging surface 311. The threaded screw shaft 315S is threaded for threading into a bone.

[0082] In some embodiments, the modular extension component can be configured to be attached to the post by a threaded engagement. In the example modular extension components 315S and 315P shown in FIG. 4K, they are configured with threaded portions 315SS and 315PS for attaching to the post 315 by a threaded engagement.

[0083] In some embodiments, the articular component 320 is an anatomic glenoid articular component 320A that comprises a concave articular surface 322 for articulating against a glenosphere.

[0084] In some embodiments, the sidewall 313 of the disc-shaped baseplate 310 can be coated with a porous material that promotes bone tissue ingrown when implanted in a glenoid.

[0085] Referring to FIGs. 4F-4H, as the glenoid implant assembly is a convertible system, the baseplate 310 can be used in reverse anatomic configuration. As shown in FIG. 4F, in the reverse configuration, a reverse anatomic glenosphere 320R is attached to the baseplate 310 via an adapter 340.

[0086] As shown in FIG. 4G, in some embodiments, the central axis Axis-B of the glenosphere 320R can be offset from the central axis Axis-A of the baseplate 310 to achieve the desired shoulder joint kinematic in the reverse anatomic configuration. To achieve this, the two sides of the adapter 340 (the first side engaging the baseplate 310 and the second side engaging the glenosphere 320R) are configured with attachment structures that are appropriately offset.

[0087] Referring to FIG. 4H, on the first side of the adapter 340 that engages the baseplate 310, the adapter can be configured with a tapered post 341 that engages the recess 312R in the baseplate 310. Similar to the glenosphere 230 that has a recess 232 for engaging its adapter 240 in the glenoid implant embodiment 200, the glenosphere 320R also can have a recess 332 that engages its adapter 340. On the second side of the adapter 340 that engages the glenosphere 320R, the adapter can be configured with a recess 342 that receives and engages a stem 320R- Stem that may be provided inside the recess 332 of the glenosphere 320R.

[0088] FIGS. 4I-4K illustrate a baseplate 310A according to another embodiment. The baseplate 310A is configured with augmentations 311 A on the bone-engaging side 311. The augmentations 311A function to fill undesired voids in the glenoid or correct to desired version or inclination. The shape, size, and specific locations of the augmentations 311 A can be customized or patient- matched for particular conditions of the patient’s bone.

[0089] Referring to FIGs. 5A-5J, a method of implanting an anatomic configuration of the glenoid implant of FIGs. 4A-4L is disclosed. Referring to FIG. 5A, a sizing template 350 is used to determing the appropriate size (i.e. diameter) of the baseplate 310 to be implanted and a hole is drilled into the glenoid for receiving the post 315 of the baseplate 310. Referring to FIG. 5B, the glenoid surface is reamed using a reamer 360 to prepare a circular recess for receiving thebaseplate 310. Referring to FIG. 5C, the baseplate 310 is implanted into the circular recess formed in the glenoid. A tool 370 configured for holding the baseplate 310 may be used for this procedure to securely inplant the baseplate 310. Referring to FIG. 5D holes for the bone screws are sized using a sizer. Referring to FIG. 5E, holes are drilled into the bone using the holes 312H in the baseplate 310 as a drill guide. Referring to FIG. 5F, bone screws 318 are threaded into the glenoid securing the baseplate 310. In embodiments of the baseplate 310 having portions that are configured with porous coatings, the bone screws 318 provide the initial fixation of the baseplate 310 and the porous coatings provide long term fixation as the bony tissue grows into the porous coatings. Referring to FIG. 5G, the second surface 312 of the baseplate is planed to have a contour that is appropriate for receiving an anatomic articular component 320A. Referring to FIG. 5H, trials are used to determine the proper size for an articular component 320A. Referring to FIG. 51, an anatomic articular component 320A is seated into the baseplate 310 using an implant holder / inserter. FIG. 5J shows the articular component 320A in implanted configuration.

[0090] Referring to FIGs. 6A-6D, a method of converting the glenoid implant system of FIGs. 4A-4L from an anatomic configuration to a reverse configuration is disclosed. Referring to FIG. 6A, the anatomic articular component 320A is removed. Referring to FIG. 6B, an optional step of planing the second surface 312 of the baseplate 310 is carried out if necessary to receive the adapter 340. Referring to FIG. 6C, the adapter 340 is attached to the baseplate 310. Referring to FIG. 6D, a reverse anatomic glenosphere 320R is attached to the adapter 340.

[0091] Although the devices, kits, systems, and methods have been described in terms of exemplary embodiments, they are not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the devices, kits, systems, and methods, which may be made by those skilled in the art without departing from the scope and range of equivalents of the devices, kits, systems, and methods.

Claims

We claim:

1. An implant for a glenoid comprising: a fixation screw including a body having a proximal end, a distal end, a proximal portion near the proximal end, and a distal portion near the distal end; and an articular body configured for articulation with a humerus or a humeral implant, wherein the articular body comprises a concave articulation surface on one side of the articular body and a distal surface on opposite side of the articular body; wherein the proximal portion of the fixation screw is threaded with a first thread having a first thread pitch and the distal surface of the articular body comprises a protrusion configured with a threaded recess for threadedly engaging the proximal portion of the fixation screw; wherein the distal portion of the fixation screw is threaded with a second thread having a second thread pitch for threading into a glenoid; and wherein the first thread pitch is smaller than the second thread pitch; and the first thread and the second thread are same handed.

2. The implant of claim 1, wherein the concave articulation surface of the articular body has a generally circular shape.

3. The implant of claim 2, wherein the articular body comprises a polymer portion that forms the concave articulation surface and a baseplate that forms the distal surface and the protrusion.

4. The implant of claim 3, wherein the distal surface and / or the protrusion comprises porous surface for promoting bone tissue ingrowth when the glenoid implant is implanted in a glenoid.

5. The implant of claim 3, wherein the distal surface has a porous surface and the protrusion has a non-porous surface.

6. The implant of claim 2, wherein the fixation screw has a longitudinal axis that defines a longitudinal axis of the glenoid implant and the distal surface is flat and extends orthogonal to the longitudinal axis of the glenoid implant.

7. The implant of claim 6, wherein the articular body comprises a sidewall that extends between the articulation surface and the distal surface and the sidewall comprises two or more grooves that extend from the articulation surface to the distal surface.

8. The implant of claim 7, wherein the two or more grooves are straight and extend parallel to the longitudinal axis of the glenoid implant.

9. The implant of claim 1, wherein the articular body comprises a polymer portion that forms the concave articulation surface and a baseplate that forms the distal surface and the protrusion.

10. The implant of claim 9, wherein the distal surface and / or the protrusion comprises porous surface for promoting bone tissue ingrowth when the glenoid implant is implanted in a glenoid.

11. The implant of claim 9, wherein the distal surface has a porous surface and the protrusion has a non-porous surface.

12. The implant of claim 1, wherein the fixation screw has a longitudinal axis that defines a longitudinal axis of the glenoid implant and the distal surface is flat and extends orthogonal to the longitudinal axis of the glenoid implant.

13. The implant of claim 12, wherein the articular body comprises a sidewall that extends between the articulation surface and the distal surface and the sidewall comprises two or more grooves that extend from the articulation surface to the distal surface.

14. The implant of claim 13, wherein the two or more grooves are straight and extend parallel to the longitudinal axis of the glenoid implant.

15. A bone anchor comprising: a hub that comprises: a bore for coupling with an anatomic glenoid articular component or a glenosphere; and at least two screw receiving portions attached to the hub by one or more arms extending outwardly from the hub, wherein each of the screw receiving portions include a hole for receiving a bone screw for anchoring the anchor to the glenoid.

16. An implant assembly kit for a glenoid, the implant comprising: an anchor that comprises:a hub having a bore for coupling with an anatomic glenoid articular component or a glenosphere; at least two screw receiving portions attached to the hub by one or more arms extending outwardly from the hub, wherein each of the screw receiving portions include a hole for receiving a bone screw for anchoring the anchor to the glenoid; at least one articular component that can be an anatomic glenoid articular component or a glenosphere; wherein the anatomic glenoid articular component comprises: a concave surface configured to articulate with a humeral component; a second surface opposite from the concave surface; and a peg extending from the second surface configured to couple with the bore in the hub; the glenosphere comprises: an outer articulating surface; and a second surface opposite from the outer articulating surface; and an adapter for attaching the glenosphere to the anchor, wherein the adapter comprises: a first side configured to engage the glenosphere; and a second side opposite from the first side comprising a peg extending from the second side configured to couple with the bore in the hub.

17. The implant assembly kit of claim 16, wherein the peg on the articular component has a length such that a distal portion of the peg extends out a distance through the hub when fully coupled with the hub and the distal portion of the peg that extends out through the hub is provided with fins on its exterior surface for holding a quantity of bone cement when the implant assembly is affixed to the glenoid.

18. The implant assembly kit of claim 16, wherein the bore in the hub is tapered and the articular component’s peg is correspondingly tapered to engage the tapered bore.

19. The implant assembly kit of claim 18, wherein the glenosphere’ s peg is correspondingly tapered to engage the tapered bore.

20. The implant assembly kit of claim 16, wherein the articular component has a plurality of protrusions, each aligned to fit into the hole provided in the screw receiving portions of the arms of the hub and prevent unwanted rotation of the articular component with respect to the anchor.

21. An implant compri sing : an anchor that comprises: three bone screws, each bone screw comprising a threaded shaft and a screw head configured with a bearing component having a convex bearing surface; and a body having three holes, each hole for receiving one of the three bone screws for anchoring the anchor to an articulating surface of a bone, wherein when the bone screws are inserted into the three holes and fully seated, the convex bearing surfaces of the three bone screws protrude from the three holes and form three- point contact bearing surface that can engage a complementary articulating component.

22. The implant of claim 21, wherein the convex bearing surface on each of the bone screw is formed of a medical grade low friction material such as polethylene.

23. The implant of claim 21, wherein the bearing components on the three bone screws can independently have same or different lengths.

24. A glenoid implant comprising: a bone screw having an elongated threaded body and a screw head that is configured with a bearing component having convex bearing surface.

25. The glenoid implant of claim 24, wherein the bearing component is formed of a medical grade low friction material such as polethylene.

26. A method comprising: preparing an articulating surface of a bone; identifying three locations on the articulating surface for forming a three-point contact surface that replaces the articulating surface; drilling a pilot hole at each of the three locations; and threading a bone screw into each of the three pilot holes, wherein the bone screw comprises an elongated threaded body and a screw head that is configured with a bearing component having convex bearing surface.

27. A glenoid implant comprising: a disc-shaped baseplate that comprises: a generally circular bone-engaging surface; a generally circular second surface opposite the bone-engaging surface; a sidewall extending between the bone-engaging surface and the second surface; a post protruding from the bone-engaging surface and centrally located on the bone-engaging surface; and an articular component that is configured to engage the baseplate via the centrally located recess on the second surface of the baseplate, wherein the articular component can be an anatomic glenoid articular component or a reverse anatomic glenosphere, wherein the second surface comprises a centrally located recess for receiving and coupling with the articular component, wherein the recess is longitudinally aligned with the post protruding from the bone-engaging surface.

28. The glenoid implant of claim 27, wherein the baseplate further comprises one or more screw receiving holes peripherally located with respect to the post, wherein each of the screw receiving holes is configured to receive a bone screw from the second surface side and holds the bone screw’s head.

29. The glenoid implant of claim 28, wherein each of the one or more screw receiving holes are configured to receive a bone screw within a range of angular orientation.

30. The glenoid implant of claim 27, wherein the post is coated with a porous material that promotes bone tissue ingrown when implanted in a glenoid.

31. The glenoid implant of claim 27, wherein the baseplate and the post are constructed as a monolithic structure.

32. The glenoid implant of claim 27, wherein the post is configured to receive a modular extension component at the post’s distal end.

33. The glenoid implant of claim 32, wherein the modular extension component is configured to be attached to the post by a threaded engagement.

34. The glenoid implant of claim 33, wherein the modular extension component is a threaded screw shaft that is threaded for threading into a bone and has one end thereof that is threaded for the threaded engagement with the post.

35. The glenoid implant of claim 27, wherein the articular component is an anatomic glenoid articular component that comprises a convex articular surface for articulating against a glenosphere.

36. The glenoid implant of claim 27, wherein the articular component is a reverse anatomic glenosphere.

37. The glenoid implant of claim 27, wherein the sidewall of the disc-shaped baseplate is coated with a porous material that promotes bone tissue ingrown when implanted in a glenoid.

Images