Mid-term results of total hip arthroplasty for relapsed osteoarthritis after joint-preserving operations for coxarthritis compared to primary total hip arthroplasty.

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Several studies have reported no differences in outcomes between total hip arthroplasty (THA) of osteotomized hips and primary hip THA. However, our results were worse after THA for converted osteotomized hips. Therefore, this study's aim was to clarify the differences between THA after osteotomy and primary THA for osteoarthritis in developmental dysplasia of the hip (DDH). The data were collected retrospectively (December 1998-June 2013). The cohort contained patients with a previous osteotomy (40 femur osteotomies) for osteoarthritis with DDH who then underwent cementless THA (average 192months after osteotomy). The clinical and radiographic outcomes of 40 hips (osteotomy group) were compared with a matched group of 40 hips after primary THA (primary group). THA was performed and investigated only in patients with DDH. The mean follow-up period of the osteotomy group was 133months. One patient was lost to follow-up. They had significantly higher subluxation and a narrower canal than the primary group (p < 0.0001, 0.017, respectively). Preoperative and final Harris Hip Score values were worse in the osteotomy group than in the primary group (preoperative 35 vs. 44, p = 0.0009; final 88 vs. 96, p = 0.0001, respectively). Manual muscle strengths of the hip flexor at final follow-up were worse in the osteotomy group. Radiographic outcomes of the osteotomy group showed a larger postoperative leg length discrepancy and severe periprosthetic bone atrophy as judged by bone mineral density and stress shielding. Proximal femoral osteotomies showed worse outcomes after conversion THA at mid-term follow-up.