Residual Acetabular Dysplasia in the Reduced Hip

Background Residual acetabular dysplasia occurs in up to a third of patients treated successfully for developmental dysplasia of the hip (DDH) and has been found to be a significant risk factor for early hip osteoarthritis (OA). Discussion Age at the time of initial reduction and the initial severity of DDH have been linked to residual acetabular dysplasia. An anteroposterior pelvic radiograph is the main diagnostic modality, but MRI also provides valuable information, particularly in equivocal cases. The literature supports intervening when significant residual acetabular dysplasia persists at 4-5 years of age, and common surgical indications include acetabular index (AI) > 25 degrees-30 degrees, lateral center-edge angle (LCEA) < 8 degrees-10 degrees, and a broken Shenton's line on radiographs; and a cartilaginous acetabular angle (CAI) > 18 degrees, cartilaginous center-edge angle (CCE) < 13 degrees, and/or the presence of high-signal intensity areas on MRI. Surgical options include redirectional pelvic osteotomies and reshaping acetabuloplasties, which provide comparable radiographic and clinical results. Conclusion RAD is common after treatment of DDH and requires regular follow-up for diagnosis and appropriate management to decrease the long-term risk of OA. Long-term outcomes of patients treated with pelvic osteotomies are generally favorable, and the risk of OA can be decreased, although the risk of total hip replacement in the long-term remains.