Long-term course of developmental dysplasia of the hip: follow-up of the non-operated hips of patients undergoing unilateral rotational acetabular osteotomy for twenty-four years.

Abstract

To follow-up the non-operated hips of patients who underwent unilateral rotational acetabular osteotomy (RAO) for bilateral developmental dysplasia of the hip (DDH) for a minimum of 20years to clarify (1) the timing of onset of hip osteoarthritis (OA) in DDH, and (2) factors associated with the development of OA. This study included 92 non-operated hips of patients who underwent unilateral RAO for bilateral DDH. We examined the timing of OA onset and total hip arthroplasty (THA) and the joint survival rate in the studied hips. Furthermore, the patients were divided into those with OA onset (progression group) and those without OA onset and compared in terms of lateral center-edge angle (LCEA), sharp angle, acetabular head index (AHI), acetabular roof obliquity (ARO), joint congruity, and the presence or absence of OA progression on the RAO side. The progression group experienced OA onset 12years after RAO and underwent THA 6years after OA onset. The 20-year joint survival rate was 73% with the endpoint of OA onset and 81% with the endpoint of THA. The progression group had significantly smaller LCEA and AHI and larger ARO. The risk of developing OA was 8.2 times greater in patients with LCEA ≤ 7° than in those with LCEA > 7°. The patients with OA progression group experienced OA onset at an average age of 55years. A small LCEA (≤ 7°) was identified as a risk factor for the development of OA.