Importance

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Abstract

An implantable bone prosthesis includes portions of two different materials which interfit with each other to form a unitary article having hard wear surface portions and strong, stiff portions for structural support. These portions are preferably formed of ceramic and of metal, respectively. The prosthesis is formed by making a multiply connected ceramic wear surface element having openings or passages therethrough, and casting the remainder of the prosthesis extending in the openings to form a mating or dendritic support or a frame interdigitated and interlocked with the ceramic wear surface. The frame may be shaped so that it contracts along a direction of shrinkage, as the casting cools, without binding against the ceramic body. In a spherical shell, such as used for the weight-bearing acetabular shell or ball joint of a hip, this is achieved with short, radially-directed interlock elements. Other connections of the two materials may include tapered bores, dovetail channels, fern-like dendritic structures, or the like. Ball and socket, trunion and other articulations are fabricated with high strength and durable wear properties.

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First Claim