Clinical performance of endoprosthetic and total hip replacement systems.

A retrospective study of endoprosthetic replacements and total hip prostheses was undertaken to determine factors that have the greatest effect on the success or failure of femoral hip components. A total of 227 endoprostheses were inserted within the years 1970-1985. Of these, 67 components (29.5 percent) required removal for various reasons. For an endoprosthesis, the most significant factor in determining the chances of success appeared to be the initial insertion diagnosis. Patients who received an endoprosthesis for an ailment which affected only the femoral side of the joint (such as traumatic fracture) had a much lower rate of failure than those patients with disease etiologies that could affect the acetabulum (such as osteoarthritis). The opposite was found for total hip prostheses. Of the 641 total hip devices inserted, 148 (23.0 percent) required removal. The highest rate of failure among these total hip components was for those devices inserted for trauma and the lowest rate of failure was for those inserted for osteoarthritis. Age at the time of insertion also proved to be of importance when estimating a hip component's chance of survival. For both endoprosthetic replacements and total hip arthroplasties, patients younger than 50 years of age at insertion experienced a failure rate almost twice that of those patients more than 50 years of age at insertion.