BACKGROUND

Field

The present disclosure relates to stemmed and stemless humeral components of a shoulder joint prosthesis.

Description of the Related Art

In a shoulder joint, the head of the humerus interacts with the glenoid cavity of the scapula in a manner similar to a “ball and socket” joint. Over time, it may become necessary to replace the shoulder joint with a prosthetic shoulder joint including a humeral component.

Traditionally, the humeral component is a single body implant having a humeral head and a stem. The stem is configured to be inserted into an intramedullary canal of the humerus. In certain cases, insertion of the stem disadvantageously requires bone to be removed to fit the stem to the canal due to patient-to-patient anatomical variation. Another disadvantage of this approach is that integration of the stem into the bone through a natural process of bone ingrowth can make it difficult to remove the humeral component if it becomes necessary to replace the humeral component with another device. Even when no removal was expected, this approach had the disadvantage of only achieving implant security after sufficient time had passed to allow for sufficient bone ingrowth.

A stemless humeral component may be used to address some of the disadvantages of conventional humeral components. Stemless humeral components can decrease the amount of bone loss in preparing the humerus to receive the component and decrease the complexity of the joint replacement procedure.

Stemless humeral component designs can be more challenging to secure to the humerus. Conventional stemless designs rely on bone ingrowth for strength. While such designs perform well over time, there is a risk in the early days and weeks after surgery where such ingrowth has not yet occurred that the stem and stemless humeral component will be dislodged from the humerus. Dislodgement may also occur due to excessive wear, forces applied thereto during a revision surgery or other high load conditions.

SUMMARY

Accordingly, there is a need for a stemless humeral component or prosthesis designed to preserve bone in initial implantation while enhancing initial pull-out resistance. Preferably enhanced initial dislodgement resistance will also provide excellent long term fixation.

The present disclosure relates to various embodiments of a stemless humeral shoulder assembly that can minimize bone loss and provide excellent initial pull-out resistance and long term fixation. Advantageously, the humeral shoulder assemblies described herein provide adequate compression, increase rotational and longitudinal stability, and encourage bone ingrowth.

Certain aspects of the disclosure are directed toward a prosthesis mounting system having a base member adapted to be driven into bone. The base member can include a central portion having a lumen extending along a longitudinal axis and a peripheral portion connected to the central portion. Further, the prosthetic mounting system can include an anchor having an inner passage sized to be advanced along the longitudinal axis of the base member. The anchor can have at least one thread surrounding the inner passage. When the anchor is coupled with the base member, the thread extends outward of the central portion of the base member.

In one embodiment, a stemless humeral shoulder assembly is provided. The assembly includes a base member and an anchor member. The base member has a distal end that can be embedded in bone and a proximal end that can be disposed at a bone surface. The base member has a plurality of spaced apart arms projecting from the proximal end to the distal end. The anchor member is advanceable into the base member to a position disposed within the arms. The anchor member is configured to project circumferentially into the arms and into a space between the arms. The anchor member is exposed between the arms when advanced into the base member. The assembly includes a recess projecting distally from a proximal end of the anchor member to within the base member. The recess is configured to receive a mounting member of an anatomical or reverse joint interface.

In another embodiment, a humeral shoulder assembly is provided that includes a stem and an anchor. The stem has a proximal region to be disposed in the metaphysis of a humerus, a distal end configured to be disposed in a canal of a humerus and a proximal end. The proximal end is to be disposed at a bone surface. The proximal region of the stem has a plurality of spaced apart projections disposed adjacent to the proximal end. The anchor is advanceable into the stem to a position disposed within the projections. The anchor is configured to project circumferentially into the projections and into a space between the projections. The anchor is exposed between the projections when advanced into the stem. The humeral shoulder assembly includes a recess that projects distally from a proximal end of the anchor to within the stem. The recess is configured to couple with an articular component.

In another embodiment, a prosthesis mounting system is provided that includes a stem and an anchor. The stem is adapted to be driven into bone. The stem has a central portion that includes a lumen. The lumen extends along a longitudinal axis. A peripheral portion of the stem is connected to the central portion. The stem extends distally of the central portion. The anchor has an inner passage sized to be advanced along the longitudinal axis. The anchor having at least one thread surrounding the inner passage. When the anchor is coupled with a proximal portion of the stem, the thread extends outward of the central portion of the base member.

Certain aspects of the disclosure are directed toward methods for treating a shoulder joint. The methods can include accessing a humeral head, resecting the humeral head, driving a base member into the humeral head, and advancing an anchor member into the base member. When the anchor member is advanced into the base member, a lateral projection of the anchor member can be disposed through the base member and can be embedded in bone adjacent to the base member. In certain aspects, the methods can also include securing a joint interface to the base member and/or the anchor member.

In another method for treating a shoulder joint, an end portion of a humerus is accessed. A stem is driven into the end portion of the humerus such that a portion of the stem extends into a canal of the humerus. An anchor member is advanced into the stem such that a lateral projection thereof is disposed through the stem and is embedded in bone adjacent to the stem. A joint interface is secured to the stem and/or the anchor member.

As described above, in certain aspects the stemless humeral component can be modular to provide more options for the surgeon during a revision surgery. For example, the modular humeral component can include a stemless fixation component adapted to be secured in the head of the humerus and a spherical head removably attached to the fixation component. During the revision surgery, the modular approach can make it easier to convert an anatomic shoulder prosthesis to a reverse shoulder prosthesis.

In any of the above-mentioned aspects, the anchor member can include a helical structure advanceable to engage corresponding surfaces of the arms. In certain aspects, the anchor can include a cylindrical sleeve and the helical structure can include at least one thread (e.g., one thread, two threads, three threads, or four threads) projecting laterally therefrom.

Any feature, structure, or step disclosed herein can be replaced with or combined with any other feature, structure, or step disclosed herein, or omitted. Further, for purposes of summarizing the disclosure, certain aspects, advantages, and features of the inventions have been described herein. It is to be understood that not necessarily any or all such advantages are achieved in accordance with any particular embodiment of the inventions disclosed herein. No aspects of this disclosure are essential or indispensable.

