CEMENTLESS FEMORAL COMPONENTS SHOULD BE MADE FROM COBALT CHROME

Before 1982, the authors performed 177 primary total hip arthroplastie s using a single-sized, extensively porous-coated cobalt-chrome femora l prosthesis. The current status of 122 of these arthroplasties is kno wn. Two femoral prostheses have been revised for late symptomatic loos ening, 2 for stem fracture, and 1 for infection. From 1982 to 1984, 22 7 primary arthroplasties were performed using the same stem in multipl e sizes. Of these cases, 171 are available for followup. One stem (0.6 %) has been revised for symptomatic loosening. Large osteolytic femora l lesions (average size, 8.1 cm(2)) developed in 3 patients, associate d with an unusually large amount of polyethylene wear of their acetabu lar components. These patients have been treated by exchange of the po lyethylene liner within the porous-coated acetabular component and all ografting of the osteolytic lesions. The femoral components were not e xchanged because osteolysis had not eroded the integrity of the suppor ting bone-implant interface to a point where loosening occurred. Befor e 1987, 193 patients with loose femoral components were treated with r evision total hip arthroplasty, also using an extensively porous-coate d cobalt-chrome femoral stem of similar design. Ten (5.7%) patients ha ve required rerevision of the femoral prosthesis. Six of these 10 rere visions were performed because of symptomatic loosening. Ninety-three percent of the patients in the primary series had relief of their preo perative pain and have improved functional ability; 94.2% are satisfie d with their results. In the revision series, 89.1% of the patients ar e free of pain and function better than preoperatively, and 89.6% are fully satisfied with their results. No extensively porous-coated impla nts that became fixed by osseointegration have developed late loosenin g or required removal because of osteolysis or stress shielding. These results justify the continued use of cobalt-chrome porous-coated femo ral prostheses in primary and revision surgery.