Various embodiments of novel glenoid implant are disclosed. The glenoid implant includes: an articular body that includes an articulation surface and a bone-facing surface on opposite side of the articular body; a metal tray attached to the bone-facing surface; and one or more holes provided in the articular body extending from the articulation surface through the articular body and the metal tray to accommodate a screw therethrough. An implant system that includes the glenoid implant and a corresponding humeral head implant is also provided.

FIELD OF DISCLOSURE

The present disclosure generally relates to glenoid implants for shoulder prosthesis.

BACKGROUND

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.

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 in the superior-inferior direction. Currently, cemented implants provide good short- and mid-term fixation, but loosen over time. The current hybrid cemented-press fit implants show similar performance. Press fit implants show high loosening at mid- to long-term time points.

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, the modular metal tray is often more stiff than desired.

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

SUMMARY

Provided herein are various embodiments of a glenoid implant that is a monolithic polymer bearing incorporating a metallic insert that allows advancement of one or more bone screws through the bearing surface resulting in enhanced fixation with the glenoid. The glenoid implant is part of a shoulder joint implant system.

According to some embodiments, a glenoid implant is disclosed that comprises: an articular body including an articulation surface and a bone-facing surface on opposite side of the articular body; a metal tray attached to the bone-facing surface; and one or more holes provided in the articular body extending from the articulation surface through the articular body and the metal tray to accommodate a screw therethrough.

According to some embodiments, a glenoid implant is disclosed that comprises: an articular body comprising an articulation surface and a bone-facing surface on opposite side of the articular body; and one or more holes provided in the articular body extending from the articulation surface through the articular body to the bone-facing surface.

According to some embodiments, an implant system is disclosed that comprises: a first articular component that is a glenoid implant that comprises: an articular body comprising an articulation surface and a bone-facing surface on opposite side of the articular body; a metal tray attached to the bone-facing surface; and one or more holes provided in the articular body extending from the articulation surface through the articular body and the metal tray to accommodate a screw therethrough; and a second articular component that is a humeral head implant configured to engage the articulation surface of the glenoid implant.

According to some embodiments, an implant system is disclosed that comprises: a first articular component that is a glenoid implant that comprises: an articular body comprising an articulation surface and a bone-facing surface on opposite side of the articular body, wherein at least the articulation surface is formed of ultra-high-molecular-weight polyethylene (UHMWPE); and one or more holes provided in the articular body extending from the articulation surface through the articular body to accommodate a screw therethrough; and a second articular component that is a humeral head implant configured to engage the articulation surface of the glenoid implant, wherein the humeral head implant comprises an articulation surface made of virgin polyether ether ketone (PEEK).

DETAILED DESCRIPTION

Provided herein are various improved glenoid bearing implants that have articulation surface that is configured to engage with an anatomical humeral head or a humeral component of a shoulder replacement implant system. Therefore, references to “a humeral head” as used herein should be construed to include both an anatomical humeral head as well as implant humeral head.

The improved glenoid bearing implant is a monolithic polymer bearing that can, in some embodiments, include a metallic insert. The glenoid bearing implant has one or more holes extending through the implant body that allows advancement of one or more bone screws through the implant body to secure the glenoid bearing implant to a glenoid. This design retains the low stiffness of a polymer bearing with the high initial fixation power of screws.

In preferred embodiments, the opposing humeral head is also a polymer so that stresses in the polymer bearing are reduced. The screws used are preferably locking type to prevent back-out into the joint space.

Referring toFIGS.1A-ID, an improved glenoid implant100for implantation in a glenoid according to the present disclosure is provided. The implant100comprises an articular body110, a metal tray120; and one or more holes115provided in the articular body110. The articular body110comprises an articulation surface112and a bone-facing surface113on the opposite side of the articular body110. The metal tray120is attached to the bone-facing surface113. The one or more holes115extend from the articulation surface112through the articular body110and the metal tray120. A screw200can be placed through the hole115to secure the implant100to a glenoid. Although an embodiment with one hole115is illustrated, the articular body110can have more than one hole115to accommodate more than one screw.

In each of the one or more holes115, a portion125of the metal tray120that forms a part of the hole115(i.e., the portion of the hole115that is extending through the metal tray120) is threaded for engaging a threaded screw head210. The threaded screw head210can be a locking type and the threads on the screw head and the threads on the metal tray portion of the one or more holes115are preferably configured to allow polyaxial locking of the screw. Allowing the screw to be locked at various angles allows the screw to be driven in the best trajectory relative to the patient anatomy. An example of such thread design is Wright Medical Technology's Ortholoc™ design, which allows screw angulation of +/−15 degrees in any direction.

In other embodiments, the locking of the screw can be monoaxial.

There are also other ways of locking a screw head into the articular body115that can be implemented in some embodiments. An example is a snap ring that can be positioned inside the hole115that the screw snaps into. The snap ring option can be useful in the all-poly articular body in the glenoid implant100A discussed below.

In some embodiments, the internal walls of the one or more holes115are not threaded at all. In such embodiments, the diameter of the holes can be sized so that the threaded head of the screws can self-tap into the holes115.

In some embodiments, the articular body110is formed of a high-modulus polymer. Some examples of such polymer are polyether ether ketone (PEEK), high-modulus polyethylene (HMPE), and ultra-high-molecular-weight polyethylene (UHMWPE), etc. that are selected to provide the desired performance for the articulation surface112. All references to UHMWPE herein includes all variants of UHMWPE in orthopedic application such as vitamin E diffused UHMWPE.

Referring toFIG.1D, which is an enlarged sectional illustration of the hole115and a bone screw200positioned therein, in some embodiments, each of the one or more holes115in the articular body has an opening at the articulation surface, the opening defining a rim116, wherein the rim is preferably chamfered to minimize the friction between the articulation surface112and the opposing humeral head. In some embodiments, the chamfer angle θ) can be about 45 degrees. The width of the chamfer is no greater than 1 mm to maximize the articulation surface area. In some embodiments, the chamfer is preferably between about 0.3-0.2 mm.

The diameter of the hole115should not be too large as that would diminish the bearing function of the articulation surface112. The diameter of the hole115also cannot be too small as it needs to accommodate a screw of sufficient diameter to establish a desired primary fixation of the implant100. The diameter of the hole115can be optimized based on these parameters. For example, in many patients, screws of 3.5-4.0 mm minimum diameter would be desired and a hole with a minimum diameter of 5 mm would accommodate such screws.

In some embodiments, the metal tray120can be made from titanium, stainless steel, an alloy of titanium, and/or an alloy of cobalt-chromium. In some embodiments, the metal tray120comprises exposed surfaces, such as the bone-facing surface113, that are coated with a coating that promotes bone in-growth. Some examples of such porous metallic material are Tritanium® by Stryker Corporation and ADAPTIS™ by Wright Medical Technology.

Referring toFIGS.1B and1C, in some embodiments, the metal tray120further comprises one or more peripheral fixation features230extending therefrom in a direction that is away from the articular body110. The one or more peripheral fixation features help provide further enhanced fixation of the implant100by preventing or minimizing rocking or micro-motion at the interface between the glenoid implant100and the glenoid.

In some embodiments of the glenoid implant100, the one or more peripheral fixation features230are posts or pegs. In some embodiments, the one or more peripheral fixation features can include a plurality of cement pockets. The illustrated peripheral fixation features230do not show such cement pockets but they can look something like the cement pockets233on the peripheral fixation features230′ of the glenoid implant100A discussed below. (SeeFIGS.2A-2C).

In some embodiments, the one or more peripheral fixation features230are integrally formed with the metal tray120so that the peripheral fixation features230are also formed of metal. In some embodiments, the one or more peripheral fixation features can be protruding extensions of the polymer articular body110and the metal tray120are configured with through holes that allow the peripheral fixation features to extend through the metal tray120.

In some embodiments where the one or more peripheral fixation features are integrally formed with the metal tray120, the one or more peripheral fixation features can be an annular ring-like structure that extends from the bone-facing surface113of the metal tray120. The annular ring-like structure can be configured as a continuous ring structure or can be configured into two or more segments. In some embodiments, the annular ring-like structure can be provided in combination with posts230. An example of such structure is seen in the glenoid implant100B embodiment discussed below.

In some embodiments where the one or more peripheral fixation features230,235are integrally formed with the metal tray120, some portion of or all of the exposed metal surfaces can be coated with a porous metal coating, such as those mentioned above, that can promote bone in-growth.

Referring toFIGS.2A-2C, an improved glenoid implant100A for implantation in a glenoid according to another embodiment is provided. The implant100A comprises an articular body110with one or more holes115provided in the articular body110. The articular body110is formed of a high-modulus polymer. A screw200can be placed through the hole115to secure the implant100A to a glenoid. The articular body110comprises an articulation surface112and a bone-facing surface113on the opposite side of the articular body110. The one or more holes115extend from the articulation surface112through the articular body110to the bone-facing surface113. Unlike the glenoid implant100, the glenoid implant100A does not include a metal tray. The hole115can be threaded for receiving a threaded head of a locking screw as discussed above in reference to the glenoid implant100. As the glenoid implant100A does not have a metal tray and is an all-polymer implant, the one or more holes115can be configured without any screw threads and sized so that the threaded head of the locking screw can self-tap into the hole115.

In some embodiments, the glenoid implant100A can include one or more peripheral fixation features230′ that are posts or pegs. In some embodiments, the one or more peripheral fixation features230′ can include a plurality of cement pockets233.

In some embodiments of the glenoid implants100A, the one or more peripheral fixation features230′ can be provided in an annular ring-like structure that extends from the bone-facing surface113of the glenoid implant100A. The annular ring-like structure can be configured as a continuous ring structure230″ as shown in the example inFIG.2D. In some embodiments, the annular ring-like structure can be configured into two or more segments. In an exemplary illustration shown inFIG.2E, the annular ring-like structure230′″ is configured into two segments in combination with posts230. An example of such structure is seen in the glenoid implant100B embodiment discussed below.

Referring toFIGS.3A-3E, an improved glenoid implant100B for implantation in a glenoid according to another embodiment is provided. The implant100B comprises an articular body110, a metal tray120B; and one or more holes115provided in the articular body110. The articular body110comprises an articulation surface112and a bone-facing surface113on the opposite side of the articular body110. The metal tray120B is attached to the bone-facing surface113. The one or more holes115extend from the articulation surface112through the articular body110and the metal tray120B. A screw200can be placed through the hole115to secure the implant100B to a glenoid. Although an embodiment with one hole115is illustrated, the articular body110can have more than one hole115to accommodate more than one screw.

In each of the one or more holes115, a portion125of the metal tray120B that forms a part of the hole115(i.e., the portion of the hole115that is extending through the metal tray120) is threaded for engaging a threaded screw head210.

Referring toFIGS.3C and3D, the metal tray120B in this embodiment includes a combination of an annular ring-like structure235B and posts230B as the peripheral fixation features for the implant100B. This configuration allows the implant100B to be a semi-inlay hybrid glenoid implant.

The polymer articular body110mates with the glenoid in an onlay arrangement while the metal tray120B which protrudes from the articular body110toward the glenoid mates with the glenoid in an inlay arrangement. The surface of the metal tray120B including the annular ring-like structure235B and the posts230B are coated with a porous metallic coating such as Tritanium® by Stryker Corporation and ADAPTIS™ by Wright Medical Technology that promotes bone in-growth. In the sectional view shown inFIG.3D, the porous coating portion C and the core metal portion M of the metal tray120B are illustrated.

As in the other embodiments described above, the screw200can be a locking type with a threaded screw head210that can lock at various angles.

The various embodiments of a glenoid implant disclosed herein can be part of an implant system for shoulder joint repair. Such implant system can comprise a first articular component that is a glenoid implant disclosed herein and a second articular component that is a humeral head implant.FIG.4is a sectional view of a such humeral head implant300, configured to engage the articular surface112of the glenoid bearing implants100,100A of the present disclosure. In some embodiments, at least the articulating surface310of the humeral head implant300is virgin PEEK to be paired with the glenoid bearing implant100,100A, where at least the articulating surface112of the glenoid bearing implant100,100A is formed by UHMWPE. In some embodiments, highly cross-linked UHMWPE-X3 manufactured by Stryker Corporation is preferred for the articulating surface112. This material combination should yield a durable implant system with prolonged life. In 3 million cycles (Mc) of wear testing in the shoulder, this material combination (PEEK/UHMWPE-X3) resulted in 85% less wear than the standard CoCr/UHMWPE-X3 combination. The articulating surface310can be either a monolithic PEEK or an overmold of a titanium taper component320. Either configuration would eliminate the current concern of dissimilar materials on either side of taper connection.

The concept of a hole in the polymer bearing is counter-intuitive in orthopedics since usually the combination of a metal head and polymer bearing creates sufficiently high contact stresses that a hole in the bearing would lead to increased wear. The use of a polymer head may make this design feasible. It is also likely only to be feasible in the shoulder or other joints which do not experience loads that are multiples of body weight.

The preferred embodiment of the PEEK head is a titanium alloy taper that is overmolded with PEEK. The titanium taper component has ridges which allow interdigitation of the PEEK into the titanium.

Reverse Shoulder Arthroplasty (RSA) Applications

In RSA applications, the bearing implant with one or more screw hole in the articulation surface can be secured to the humeral stem implant. The screw fixation for the bearing implant would provide enhanced stable fixation of the bearing implant in RSA application also.

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.