Isoelastic femoral component in primary cementless total hip arthroplasty

We followed 100 patients (111 hips) who underwent primary total hip arthroplasty between July 1988 and June 1995 using the isoelastic femoral component. The average age was 61 (30-70) years. Mean follow-up time was 8.4 (5-12) years. Three femoral components were revised for aseptic loosening and one for disabling thigh pain. Six additional femoral components were considered probably loose by the radiographic criteria. Osteolysis around the femoral component was noted in only two patients who were clinically asymptomatic. A high incidence (41%) of lateral migration of the tip of the femoral components was noted, but there was no significant distal migration. Nine patients complained of thigh pain, which interfered with their daily activities. The average Harris hip score improved from 49 to 80 at the latest follow-up. We believe that the principle of isoelasticity in hip replacement is important; however, improvements in the material and the design of the femoral component are required.