Locking mechanism for acetabular cup

摘要

An implantable orthopedic prosthesis is provided that includes a shell having a substantially concave inner surface defining a cavity and a substantially annular groove formed therein. The prosthesis further includes a polymeric insert that is positionable within the cavity of the shell, and that has a substantially convex outer surface and a circumferential protrusion projecting therefrom. The protrusion has a substantially trapezoidal cross-section wherein at least one of the sides of the trapezoid is substantially parallel to the axis of symmetry of the insert. The cross-section of the protrusion is substantially congruent to the cross-section of the groove of the shell, and the inner surface of the shell is substantially congruent with a corresponding portion of the outer surface of the insert when the insert is properly positioned within the cavity of the shell.