Methods, systems, and apparatus for implanting prosthetic devices into cartilage

1. A method of implanting a prosthetic acetabular cup into a patient, comprising:

gaining access to an acetabulum of the patient, the acetabulum comprising an inner portion formed of bone and an outer portion formed of articular cartilage;

creating a first engagement feature within the articular cartilage of the outer portion of the acetabulum without removing any portion of bone from the inner portion of the acetabulum, the first engagement feature sized, shaped, and positioned to mate with a second engagement feature of the prosthetic acetabular cup; and

securely anchoring the prosthetic acetabular cup with the acetabulum by engaging the second engagement feature of the prosthetic acetabular cup with the first engagement feature in the articular cartilage of the outer portion of the acetabulum.

2. The method of claim 1 , wherein creating the first engagement feature comprises creating a recess in the articular cartilage.

3. The method of claim 2 , wherein creating the recess comprises forming an annular recess in the articular cartilage with a depth between about 0.5 mm and about 2.0 mm.

4. The method of claim 2 , wherein securely anchoring the prosthetic acetabular cup comprises engaging the second engagement feature of the prosthetic acetabular cup with the recess in the articular cartilage, where the second engagement feature comprises a projection extending from an outer surface of the prosthetic acetabular cup.

5. The method of claim 3 , wherein creating the first engagement feature comprises forming a projection in the articular cartilage.

6. The method of claim 1 , wherein securely anchoring the prosthetic acetabular cup further comprises creating a liquid adhesion bond between the prosthetic acetabular cup and the articular cartilage of the outer portion of the acetabulum.

7. The method of claim 6 , wherein creating the adhesion bond comprises wetting an outer surface of the prosthetic acetabular cup prior to snap-fitting the snap-fit structure of the prosthetic acetabular cup into the recess.

8. The method of claim 1 , wherein creating the first engagement feature comprises forming a plurality of recesses in the articular cartilage.

9. The method of claim 8 , wherein the plurality of recesses are substantially aligned to form an annular array of recesses in the articular cartilage.

10. The method of claim 8 , wherein each of the plurality of recesses comprises an annular recess in the articular cartilage, each of the plurality of recesses being spaced from one another.

11. A method of implanting a polycarbonate polyurethane prosthetic acetabulum into a hip joint of a patient, comprising:

gaining access to a natural acetabulum of the patient, the natural acetabulum comprising a first outer portion for articulating engagement with a femoral head of the patient, the first outer portion formed of articular cartilage, the natural acetabulum further comprising a second inner portion adjacent the first outer portion, the second inner portion formed of bone;

removing a portion of the articular cartilage of the first outer portion without damaging any bone of the second inner portion to create at least one first anchoring structure within the articular cartilage, the at least one first anchoring structure shaped to mate with at least one second anchoring structure of the prosthetic acetabulum; and

engaging the prosthetic acetabulum with the first outer portion of the acetabulum such that an outer engagement surface of the prosthetic acetabulum engages the first outer portion of the acetabulum via a liquid adhesion bond and the at least one second anchoring structure of the prosthetic acetabulum engages the at least one first anchoring structure in the articular cartilage, wherein the engagement of the at least second anchoring structure of the prosthetic acetabulum prevents unwanted rotation of the prosthetic acetabulum relative to the first outer portion of the natural acetabulum and the liquid adhesion between the prosthetic acetabulum and the first outer portion prevents unwanted separation of the prosthetic acetabulum from the first outer portion.

12. The method of claim 11 , wherein removing the portion of the articular cartilage comprises creating an annular recess in the articular cartilage.

13. The method of claim 11 , wherein removing the portion of the articular cartilage comprises removing between about 0.5 mm and about 2.0 mm of articular cartilage depth.

14. The method of claim 11 , wherein removing the portion of the articular cartilage comprises engaging an anchoring portion of a tool with a portion of the natural acetabulum and rotating a cutting portion of the tool about a longitudinal axis of the tool relative to the anchoring portion to form the at least one recess in the articular cartilage.

15. The method of claim 14 , wherein engaging the anchoring portion of the tool with the portion of the natural acetabulum comprises engaging the anchoring portion with a bony portion of the hip joint.

16. The method of claim 14 , wherein engaging the anchoring portion of the tool with the portion of the natural acetabulum comprises engaging the anchoring portion with the articular cartilage of the first outer portion without damaging the articular cartilage.

17. The method of claim 16 , further comprising wetting the outer engagement surface of the prosthetic acetabulum with a liquid configured for creating the liquid adhesion bond prior to engaging the prosthetic acetabulum with the first outer portion of the natural acetabulum.

18. The method of claim 17 , further comprising saturating the prosthetic acetabulum with the liquid configured for creating the liquid adhesion bond prior to engaging the prosthetic acetabulum with the first outer portion of the natural acetabulum.

19. A method of implanting a flexible prosthetic acetabular cup into a patient, comprising:

gaining access to the acetabulum of the patient, the acetabulum comprising an inner portion formed of bone and an outer portion formed of articular cartilage;

determining whether the articular cartilage of the outer portion is suitable for receiving the flexible prosthetic acetabular cup;

engaging an anchoring portion of a tool with the articular cartilage and rotating a cutting portion of the tool about a longitudinal axis of the tool relative to the anchoring portion to form a recess in the articular cartilage without removing any portion of the bone from the inner portion of the acetabulum, the recess shaped to mate with an engagement structure of the flexible prosthetic acetabular cup and having a depth between about 0.5 mm and about 2.0 mm; and

securing the flexible prosthetic acetabular cup to the articular cartilage, including positioning the engagement structure of the flexible prosthetic acetabular cup into the recess in the articular cartilage of the outer portion of the acetabulum.

20. The method of claim 19 , wherein determining whether the articular cartilage of the outer portion is suitable for receiving the flexible prosthetic acetabular cup comprises imaging the patient's hip joint to determine a thickness of the articular cartilage, wherein the thickness must be at least 2 mm for the articular cartilage to be considered suitable.