Mobile bearing glenoid prosthesis

1. A prosthesis assembly configured for use with a scapula, comprising:

a spherical humeral component;

a stretched glenoid bearing including a first bearing surface with (i) a first spherical outer portion with a first radius of curvature, (ii) a second spherical outer portion with a second radius of curvature, (iii) a central portion located between the first spherical outer portion and the second spherical outer portion, said central portion including a substantially flat portion, and (iv) a first mating portion extending from a second bearing surface opposite the first bearing surface and including a first locking component; and

a base configured to rotatably support the stretched glenoid bearing, the base including a second mating portion configured to receive the first mating portion and including a second locking component, wherein

the first radius of curvature is substantially equal to the second radius of curvature and the central portion does not have a radius of curvature that is substantially equal to the second radius of curvature, and

the first locking component and the second locking component are configured such then when the first locking component and the second locking component are engaged, the first and second locking components limit (i) axial movement of the first mating portion with respect to the second mating portion, and (ii) rotation of the stretched glenoid bearing to less than 360 degrees.

2. The prosthesis assembly of claim 1 , wherein the base comprises:

a glenoid vault-occupying portion configured to occupy at least a portion of a cavity in a glenoid vault, the glenoid vault-occupying portion including an outer wall; and

a rim, wherein the rim and the outer wall define a pocket.

3. The prosthesis assembly of claim 2 , wherein:

the first mating portion includes a third locking component; and

the second mating portion includes a fourth locking component configured to rotatably couple with the third locking component.

4. The prosthesis assembly of claim 1 , wherein:

the first bearing surface includes a non-circular outer periphery.

5. The prosthesis assembly of claim 4 , wherein:

the base includes a non-circular outer periphery; and

the second mating portion includes a circular periphery.

6. The prosthesis assembly of claim 1 , wherein:

the first locking component extends about an outer periphery of the first mating portion;

the second locking component extends about an inner periphery of the second mating portion; and

the length of the first locking component about the outer periphery is less than the length of the second locking component about the inner periphery.

7. A prosthesis assembly configured for use with a scapula, comprising:

a spherical humeral component;

a stretched glenoid bearing including a first bearing surface with (i) a first spherical outer portion with a first radius of curvature, (ii) a second spherical outer portion with a second radius of curvature, (iii) a central portion located between the first spherical outer portion and the second spherical outer portion, said central portion including a substantially flat portion, and (iv) a first mating portion extending from a second bearing surface opposite the first bearing surface and including a first locking component; and

a base including (i) a third bearing surface, and (ii) a second mating portion extending from the third bearing surface and including a second locking component, the base configured to rotatably support the stretched glenoid bearing, wherein

the central portion includes a radius of curvature that is not substantially equal to the first radius of curvature or the second radius of curvature, and

the first locking component and the second locking component are configured such then when the first locking component and the second locking component are engaged, the first and second locking components limit (i) axial movement of the first mating portion with respect to the second mating portion, and (ii) rotation of the stretched glenoid bearing to less than 360 degrees.

8. The prosthesis assembly of claim 7 , wherein:

the first mating portion is substantially conical; and

the second mating portion is configured to receive the first mating portion.

9. The prosthesis assembly of claim 8 , wherein a periphery of the third bearing surface is generally oval.

10. The prosthesis assembly of claim 8 , wherein the base comprises:

a bone contacting surface on a side of the base opposite to the third bearing surface; and

a stem extending outwardly from the bone contacting surface.

11. The prosthesis assembly of claim 10 wherein the base is metallic, the base further comprising:

at least one fin extending outwardly from the stem.

12. The prosthesis assembly of claim 8 , wherein:

the first mating portion includes a third locking component; and

the second mating portion includes a fourth locking component configured to rotatably couple with the third locking component.

13. The prosthesis assembly of claim 12 , wherein:

the first locking component extends about an outer periphery of the first mating portion; and

the second locking component extends about an inner periphery of the second mating portion.

14. The prosthesis assembly of claim 13 , wherein:

the length of the first locking component about the outer periphery is less than the length of the second locking component about the inner periphery.

15. The prosthesis assembly of claim 7 , wherein the first radius of curvature is substantially equal to the second radius of curvature.