Anatomic Hip Center Decreases Aseptic Loosening Rates After Total Hip Arthroplasty with Cement in Patients with Crowe Type-II Dysplasia: A Concise Follow-up Report at a Mean of Thirty-six Years.

UNLABELLED: We previously reported the two to twenty-two-year results of 145 total hip arthroplasties (THAs) with cement performed from 1969 to 1980 in 117 patients with Crowe type-II dysplasia. The purpose of the present study was to update the long-term effects of a nonanatomic hip center on component loosening and aseptic revision in this cohort. Forty-nine patients (sixty hips) were alive at a mean of thirty-six years. The overall cumulative incidence of aseptic revision at thirty-five years was 32% for acetabular cups and 21% for femoral stems. Acetabular loosening was less likely with a hip center placed within the true acetabular region (TAR), <15 mm superior to the approximate femoral head center (AFHC), <35 mm superior to the interteardrop line (ITL), or within zone 1. Femoral loosening and revision were less likely with the hip center placed <35 mm superior to the ITL and within zone 1. An anatomic hip center was associated with significantly lower loosening and aseptic revision rates for both acetabular and femoral components. The current study supports the placement of acetabular components in an anatomic position to promote long-term durability after THA with cement. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.