Implant and anchor assembly

1. An implant assembly comprising:

an implant having a load bearing surface with a contour corresponding to a patient's articular surface, and a bone facing surface including a first fixation element;

an anchor configured to be secured to bone beneath said patient's articular surface, said anchor including a second fixation element; and

wherein said first fixation element is configured to be secured to said second fixation element;

wherein said first fixation element and said second fixation element are configured to mechanically connect with each other to form a mechanical connection therebetween, said first fixation element and said second fixation element are further configured to frictionally engage with each other to form a frictional connection therebetween;

one of said first fixation element and said second fixation element comprises a protrusion comprising a protrusion sidewall having an exterior surface, an interior surface defining a cavity, and a thickness extending therebetween;

said protrusion sidewall includes at least one protrusion sidewall fixation feature, said at least one protrusion sidewall fixation feature comprises a plurality of ribs and at least one plurality of relief recesses extending through the exterior surface of the protrusion sidewall to a non-zero distance from the interior surface of the protrusion sidewall, and wherein the plurality of ribs are separated by the plurality of relief recesses.

2. The implant assembly of claim 1 , wherein:

said at least one relief recesses extends longitudinally along a longitudinal length of said protrusion.

3. The implant assembly of claim 1 , wherein:

said plurality of ribs are substantially equally spaced around a circumference of said protrusion.

4. The implant assembly of claim 1 , wherein:

said plurality of ribs are substantially parallel to each other.

5. The implant assembly of claim 1 , wherein:

said implant comprises plastic; and

said first fixation element and said second fixation element each comprise metal.

6. The implant assembly of claim 1 , wherein:

said implant comprises metal; and

said first fixation element and said second fixation element each comprise plastic.

7. The implant assembly of claim 1 , wherein:

said first fixation element and said second fixation element are further configured to mechanically interlock with each other to form a positive mechanical engagement therebetween.

8. The implant assembly of claim 7 , wherein:

said first fixation element comprises a tapered recess; and

said second fixation element comprises a tapered protrusion.

9. The implant assembly of claim 7 , wherein:

said first fixation element comprises a tapered protrusion; and

said second fixation element comprises a tapered recess.

10. The implant assembly of claim 7 , wherein:

one of said first fixation element or said second fixation element comprises a protrusion having a protrusion sidewall; and

said protrusion sidewall includes at least one protrusion sidewall fixation feature;

and said other of said first fixation element or said second fixation element comprises a recess having a recess sidewall; and

said recess sidewall includes at least one recess sidewall retention feature.

11. The implant assembly of claim 10 , wherein:

said at least one protrusion sidewall fixation feature is configured to mate with said at least one recess sidewall fixation feature to form said mechanical interlock.

12. The implant assembly of claim 10 , wherein:

said at least one protrusion sidewall fixation feature comprises at least one barb;

said at least one recess sidewall fixation feature comprises at least one ridge; and

said at least one barb is configured to cooperate with said at least one ridge to form said mechanical interlock.

13. The implant assembly of claim 10 , wherein:

said at least one protrusion sidewall fixation feature comprises at least one projection; and

said at least one recess sidewall fixation feature comprises at least one indentation;

and said at least one projection is configured to mate with said at least one indentation to form said mechanical interlock.

14. The implant assembly of claim 1 , wherein:

said first fixation element is formed by an implant body and an implant fixation member.

15. The implant assembly of claim 14 , wherein:

said implant body and said implant fixation member are secured to one another by at least one of a friction fit connection, a positive mechanical engagement connection and an adhesive connection.

16. The implant assembly of claim 1 , wherein:

at least a portion of said anchor includes a threaded portion configured to engage said bone.

17. The implant assembly of claim 1 , wherein:

said implant is a synovial joint implant, a ball and socket joint implant or a shoulder joint implant.

18. The implant assembly of claim 1 , wherein:

said at least one protrusion sidewall fixation feature comprises at least one barb.

19. The implant assembly of claim 18 , wherein:

said at least one barb forms a ring extending continuously around said circumference of said protrusion.

20. The implant assembly of claim 18 , wherein said at least one barb forms a ring comprising a plurality of barb ring segments which extend around said circumference of said protrusion.