PROSTHETIC COMPONENT FAILURES IN HIP-ARTHROPLASTY SURGERY

A survey was conducted of the entire membership of the American Associ ation of Hip and Knee Surgeons to determine their experience with tota l hip arthroplasty (THA) device-related failures. Forty-seven percent of the membership reviewed their preceding 5-year clinical experience and returned the survey instrument. The aggregate 5-year volume encomp assed experience with more than 60,000 hip arthroplasties. The median 5-year experience per respondent was 200 metal-backed sockets and 214 metal stems. The frequency distribution of the number of hip arthropla sties per respondent was skewed to the right, with fewer surgeons repo rting the higher volumes of arthroplasties. In aggregate, 60,115 of th e acetabular components used were metal backed. Nonmetal acetabular co mponent usage totaled 3,219. Complete polyethylene failure was defined as fracture or complete wear through of the polyethylene portion of t he component. Complete polyethylene failure was seen in 172 metal-back ed sockets (29/10,000). Seventy-seven all-polyethylene sockets had com plete polyethylene failure (239/10,000). A total of 87 THAs were revis ed for modular acetabular dissociations for a dissociation rate of 15/ 10,000. In aggregate, 64,483 metal-stemmed components were used. Femor al stem fractures occurred in 172 for a rate of 27/10,000. A total of 56,965 metallic femoral components were reported as being modular. Dis sociation between the femoral head and neck was uncommonly seen (3/10, 000). Use of ceramic femoral heads was low (5,023); however, a total o f 11 ceramic head fractures were revised in the 5-year period for a fa ilure rate of 22/10,000. The risks of catastrophic prosthetic THA fail ure are low but vary according to hip component and the manufacturer o f the part. On the basis of this survey, polyethylene is the weakest l ink in THA prosthetic design. Manufacturers' efforts should continue t o address factors leading to polyethylene failure, in addition to the other factors that result in premature prosthetic hip failures. Surgeo ns and patients may use this information to assist in the selection of quality manufacturers as preferred vendors. Because of the low freque ncy of device failures, the large simple survey methodology can provid e failure rate estimates that cannot be reliably determined by individ ual orthopaedists or institutions working in isolation.