| 摘要 |
A joint prosthesis device comprises a head configured to fit within a cup. The cup includes a concave cup surface defined by at least one radius of curvature R<SUB>C</SUB>. The head includes a convex head surface defined by at least one radius of curvature R<SUB>H</SUB>. The convex head surface is configured to engage the concave cup surface. The convex head surface provides an articulation zone where the head surface engages the cup surface. R<SUB>C </SUB>differs from R<SUB>H </SUB>in the articulation zone by a first amount. The convex head surface also provide a peripheral zone outside of the articulation zone. R<SUB>C </SUB>differs from R<SUB>H </SUB>in the peripheral zone by a second amount that is greater than the first amount. The peripheral zone generally extends over an area subtended by a minimum angle having a vertex at a center of the head.
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