| 摘要 |
PCT No. PCT/GB91/01078 Sec. 371 Date Mar. 15, 1993 Sec. 102(e) Date Mar. 15, 1993 PCT Filed Jul. 3, 1991 PCT Pub. No. WO92/00709 PCT Pub. Date Jan. 23, 1992.A joint prosthesis for a human or animal body, which comprises first (20) and second (40) components each made of bio-compatible material and adapted for secural to respective bones (13,14) of the body in the vicinity of a natural joint (16) after surgical excision of the natural joint (16). The components (20,40) of the prothesis (12) are unattached to each other and, in use, are held together to form the joint by the natural ligaments, tendons and muscles of the body in the vicinity of the natural joint (16). The first component (20) comprises a stem (21) for reception by a bone cavity and a bulbous head (22) presenting a three-dimensionally curved convex articulation surface (23) which in the sagittal plane has a radius of curvature which changes within the arc length of the surface in that plane and which has a length of at least 90 DEG . The second component (40) comprises a stem (41) for reception by a bone cavity and a head (42) presenting a three-dimensionally curved concave articulation surface (43) which is dimensioned to slide over the convex surface (23) substantially along the 90 DEG arc length. This provides flexing movement of the prosthetic joint with the instantaneous center of rotation of the joint changing during the flexing movement due to the changes of radius of curvature so as to change the distance between the respective bones (13,14) and thereby allow natural collateral ligament function around the prosthetic joint to aid flexor muscle effect when the joint is extended and extensor muscle effect when the joint is flexed.
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