Quality of reduction and prognosis of developmental dysplasia of the hip: a retrospective study.

INTRODUCTION: Using limited MRI we evaluated the quality of closed reduction and prognosis in a group of patients with developmental dysplasia of the hip (DDH).

METHODS: Limited MRI was performed on 28 DDH patients (41 hips) after closed reduction. All the hips were divided into deep and incomplete concentric reduction groups according to the femoral head-acetabular distance (FAD) and the shape of the labrum on limited MRI. The abduction angle of the hips, and the initial and final acetabular index (AI) were measured. Presence or absence of the ossification centre of the femoral head before treatment, the Tönnis classification and avascular necrosis of the femoral head and types (Bucholz and Ogden type) were recorded. The data of the 2 groups were analysed with SPSS software.

RESULTS: We found no significant differences in age, gender, side, preoperative ossification centre of the femoral head, preoperative AI, decreased postoperative AI and abduction angles of hips between the 2 groups. There were significant statistical differences in the preoperative Tönnis grade, FAD after reduction, AI at the final follow-up, severe residual deformity and severe avascular necrosis of the femoral head (p<0.05). The cure rate showed a significant trend (p = 0.052).

CONCLUSIONS: Limited MRI enables effective determination of the quality of reduction immediately after closed reduction. The prognosis of the deep concentric reduction group was better than the group with incomplete concentric reduction.