Background: The early experience with cementless total hip replacement led to design modifications to increase the initial press-fit and stability of the femoral component, to reduce the diameter of the femoral head, and to improve the acetabular component, including the locking mechanism of the shell and the quality of the polyethylene liner. We performed a prospective study to assess the results in young patients who had been followed for a minimum of eight years after treatment with a primary total hip arthroplasty with a second-generation cementless prosthesis.
Methods: Eighty patients (118 hips) were included in the study. There were fifty-eight men and twenty-two women; the mean age at the time of the operation was 46.8 years (range, twenty-one to forty-nine years). We used a cementless Duraloc series-100 or 1200 acetabular component with or without screw fixation, a polyethylene liner with a 22-mm inner diameter, and a cementless Profile femoral component in all hips. The average duration of follow-up was 9.8 years (range, eight to eleven years). Clinical follow-up (with use of the Harris hip score) and radiographic follow-up were performed at six weeks; at three, six, and twelve months; and yearly thereafter. Linear and volumetric wear were measured, and bone-remodeling and osteolysis were assessed.
Results: The average Harris hip score improved from 48.8 points preoperatively to 92 points at the final follow-up examination. The prevalence of transitory thigh pain was 10% (twelve of 118 hips). There was no aseptic loosening. One hip was revised because of recurrent dislocation. The average amount of linear wear was 1.18 mm, and the average wear rate was 0.12 mm/yr. Fourteen hips (12%) had osteolysis in the calcar femorale and eleven hips (9%) had acetabular osteolysis, but all of the osteolytic lesions were <1 cm
Conclusions: The mechanical fixation of the anatomic fit cementless Profile stem was excellent in this study of young patients who were particularly difficult to treat because of a high prevalence of osteonecrosis and developmental dysplasia. Although there was no aseptic loosening of the components and a relatively low prevalence of osteolysis, there was a high rate of linear wear of the polyethylene liner.
Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.