Bearing fixation

1. A system for an acetabular prosthesis to fix a bearing liner within a shell, comprising:

a shell member having an exterior configured to engage an anatomy and a concave interior;

a bearing liner having an exterior wall surface configured to be received within the concave interior of the shell member, the exterior wall surface extending from a rim of the bearing liner towards an apex of the bearing liner along a substantially continuous curve, and an axial fixation projection extending from the substantially continuous curve of the exterior surface;

wherein the axial fixation projection has a first projection surface extending from the exterior surface a first distance and at least one second surface extending towards the exterior surface at an acute angle relative to the first projection surface;

wherein at least 51 percent of the material that forms the axial fixation projection is between a midline of the axial fixation projection and the apex of the bearing;

wherein the axial fixation projections engages the shell to engage the bearing liner within the concave interior of the shell.

2. The system of claim 1 , wherein the first projection surface is substantially perpendicular to a bearing liner axis extending from the apex past the rim.

3. The system of claim 2 , wherein the rim defines a bearing plane and the bearing liner axis is substantially perpendicular to the bearing plane and intersects the apex.

4. The system of claim 1 , wherein the concave interior is substantially hemispherical.

5. The system of claim 1 , wherein the shell defines a groove formed into a wall surface of the concave interior, wherein the axial fixation projection is received within the groove when the bearing liner is seated within the shell.

6. The system of claim 1 , further comprising:

proximal femoral member configured to be implanted into a femur to articulate within the positioned bearing liner.

7. The system of claim 1 , wherein the at least one second surface includes a plurality of second surfaces that together extend from an exterior end of the first projection surface to the substantially continuous curve of the exterior surface of the bearing liner.

8. A system for an acetabular prosthesis to fix a bearing liner within a shell, comprising:

a shell member having an exterior configured to engage an anatomy and a concave interior surface extending from a shell rim to a shell apex, an engagement groove is defined through the concave interior surface;

a bearing liner having an exterior wall surface configured to be received within the concave interior of the shell member, the exterior wall surface extending from a rim of the bearing liner towards an apex of the bearing liner along a substantially continuous curve, an asymmetrical axial fixation projection extending from the substantially continuous curve of the exterior wall surface;

wherein the asymmetrical axial fixation projection has a first configuration where a volume of material of the asymmetrical axial fixation projection is biased towards the apex of the bearing liner;

wherein the asymmetrical axial fixation projection engages the engagement groove of the shell to engage the bearing liner within the concave interior of the shell in a locking configuration that is deformed from the first configuration due to insertion into the shell and engaging the engagement groove in a second configuration.

9. The system of claim 8 , wherein the groove is substantially continuous around the concave interior surface.

10. The system of claim 8 , wherein the axial fixation projection is discontinuous around the exterior of the bearing liner.

11. The system of claim 8 , wherein the asymmetrical axial fixation projection includes a first projection surface extending from the exterior surface substantially perpendicular to a central axis of the liner and having a surface end a first distance from the exterior surface and positioned a first distance from the rim of the liner;

wherein the asymmetrical axial fixation projection further includes at least one second surface extending towards the central axis at an acute angle relative to the first projection surface and positioned a second distance from the rim, wherein the second distance is less than the first distance.