Ludloff's medial approach has been described as a simple procedure for open reduction of developmental dysplasia of the hip (DDH) requiring minimal dissection and tissue disruption. Many patients undergo subsequent reconstruction of the acetabulum after skeletal maturity for residual dysplasia. Femoral head deformity reportedly influences the long-term outcome of these osteotomies. The literature suggests this deformity may be related to the patient's age at the time of a medial approach. We therefore asked whether femoral head deformity (roundness index, femoral head enlargement) at skeletal maturity correlates with patient age at surgery. We assessed the radiographs of 40 patients (42 hips). Their mean age at surgery was 14.3 months (range, 6-31 months); the minimum followup was 10 years (mean, 15.8 years; range, 10-27 years). The mean roundness index at skeletal maturity correlated with increased age at the time of the operation (mean index, 58.3; range, 47-79) while enlargement did not. Using a medial approach for correction of DDH in older patients increases the risk of femoral head deformity at skeletal maturity.