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RESEARCH PRODUCT

Quantitative computed tomography-assisted osteodensitometry of the pelvis after press-fit cup fixation: a prospective ten-year follow-up.

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Background: As a follow-up of a previously reported three-year study, we analyzed the periprosthetic acetabular cortical and cancellous bone density changes at ten years after implantation of a press-fit cup. Methods: Prospective clinical, radiographic, and quantitative computed tomography examinations were performed within ten days and at mean periods of one, three, and ten years after total hip arthroplasty with a press-fit cup, a femoral stem with a tapered design, and alumina-alumina pairing. Periacetabular cortical and cancellous bone density (mg CaHA/mL) in the cranial, ventral, and dorsal regions about the cup were measured for twenty-four hips in vivo. Results: All acetabular cups showed radiographic signs of stable ingrowth, and no acetabular component had to be revised. The loss of periacetabular cancellous bone density about the cup was as much as –37% cranially, –60% ventrally, and –71% dorsally; the decrease was progressive between the one-year and three-year examinations only. In contrast, cortical bone density above the dome of the acetabular cup remained constant throughout the ten-year follow-up. A moderate change in cortical bone density of –5% to –18% was seen at the level of the cup ten years postoperatively. Conclusions: Both periacetabular cortical and cancellous bone density changes were nonprogressive between the three-year and ten-year examinations after press-fit cup fixation. Clinical Relevance: Ten years postoperatively, the measured periacetabular cortical and cancellous bone density changes had no influence on the good clinical and radiographic performance of the cup.