An orthopedic prosthetic implant comprises a metal alloy stem element (13, 63, 113), which has one end portion (19, 69, 119) constructed to reside in the medullary cavity of a bone and an integral connector (23, 73, 123) at the opposite end to which crystalline brittle head (17, 67, 117), preferably made of pyrocarbon-coated graphite, is joined. The head interfaces with human bone, and its effective joinder to the stem element is achieved through a polymeric insert (15, 65, 115) of proportional shape and design which has selected elastic properties. The design and material of the polymeric insert allow it to be securely received within an interior cavity (35, 77, 131) of the pyrocarbon-coated graphite head and mated to the stem connector in an either rigidly or bi-polar arrangement. The method of joinder allows the construction of composite implants that utilize the most desirable properties of metallic and brittle crystalline materials.