Postoperative excessive anterior acetabular coverage is associated with decrease in range of motion after periacetabular osteotomy

PURPOSE: The aim of this study was to evaluate the relationship between acetabular 3-dimensional (3D) alignment reorientation and clinical range of motion (ROM) after periacetabular osteotomy (PAO). METHODS: 50 patients (58 hips) with hip dysplasia participated in the study and underwent curved PAO. The pre- and postoperative 3D centre-edge (CE) angles and femoral anteversion were measured and compared with clinical outcomes, including postoperative ROM. RESULTS: The correlation between pre- and postoperative acetabular coverage and postoperative ROM was evaluated. Postoperative abduction and internal rotation ROM were significantly associated with postoperative lateral CE angles (abduction; p < 0.001, internal rotation; p = 0.028); flexion and internal rotation ROM was significantly associated with postoperative anterior CE angles (flexion; p < 0.001, internal rotation; p = 0.028). Femoral anteversion was negatively correlated with postoperative abduction (p = 0.017) and external rotation (p = 0.047) ROM. CONCLUSION: Postoperative anterior acetabular coverage may affect internal rotation ROM more than the lateral coverage. Therefore, the direction of acetabular reorientation should be carefully determined according to 3D alignment during PAO.