Bone Quality and Results of Third Generation Cementless Total Hip Arthroplasty in Patients With Osteonecrosis of the Femoral Head
YH Kim, JS Kim
The Joint Replacement Center, Ewha Womans University College of Medicine, Seoul, Korea

Background: A potential cause of premature loosening of the total hip prosthesis in patients with osteonecrosis is abnormal cancellous bone in acetabulum and proximal femur. The purpose of this prospective study was to investigate the hypothesis that osteonecrosis is not confined to the femoral head but may extend proximally into acetabulum and distally into proximal femoral bone. Also, the clinical and radiographic results of total hip arthroplasty with so-called third-generation cementless total hip prosthesis were evaluated in sixty-three consecutive patients with osteonecrosis of the femoral head.

Methods: Twenty-five patients who had had simultaneous bilateral total hip arthroplasty and thirty-eight patients who had a unilateral total hip arthroplasty were included in the study. A cementless acetabular and femoral component were used in all hips. There were fifty-five men and eight women. The mean age at the time of the arthroplasty was 47.1 years (range, twenty-five to sixty-four years). We performed histological examination of the femoral heads and cancellous bone biopsies from five regions of the hip in patients undergoing total hip arthroplasty. Clinical and radiographic evaluations were performed preoperatively; at six weeks; at three, six, and twelve months; and yearly thereafter. The average duration of follow-up was 4.9 years.

Results: The majority of patients with idiopathic or alcohol induced osteonecrosis had normal bone in the acetabulum and proximal femur. The average Harris hip scores in the group treated with unilateral arthroplasty (96 points) and the group treated with bilateral arthroplasty (94 points) were similar at the time of final follow-up. No component had aseptic loosening. In one hip (1%), an acetabular component and a femoral component were revised because of infection. No hip had a detectable wear or osteolysis in the acetabulum or in the proximal femur.

Conclusions: Normal or nearly normal cancellous bone in the acetabulum and proximal femur and advancements in surgical technique and better designs have greatly improved the intermediate-term survival of cementless total hip implants in young patients with osteonecrosis of the femoral head. An absence of osteolysis in these high-risk young patients is partly related to: use of ceramic-on-ceramic bearing; solid fixation of the component; and the follow-up was not long enough.