Historical review of porous-coated implants.

The implementation of cementless joint replacement prostheses is proving to be a significant advance in orthopedic surgery. The porous-coated implant, stabilized by the biologic fixation resulting from bone ingrowth, is one of several types of cementless devices. A historical review of porous materials reveals that the concepts underlying biologic fixation date back decades. It was the initial concerns about the long-term performance of bone cement that, in the early 1970s, stimulated several groups more actively to pursue the development of porous systems. As a result of their efforts, there are currently many different porous coatings and prosthetic designs undergoing clinical investigation, with generally encouraging results. However, it is becoming clear that the importance of porous-coated prosthetic devices is not that they will serve to replace cemented prostheses entirely, but rather that they offer viable alternatives for the treatment of certain populations of patients. An understanding of the evolution of porous-coated implants can help to identify gaps in our knowledge and areas that require additional study, to direct future design modifications of implants, and to foster effective implementation of the prostheses.