IS SUFFICIENT FEMORAL HEAD COVERAGE OBTAINED AFTER PEMBERTON’S PERICAPSULER OSTEOTOMY? AN EVALUATION BY THREE-DIMENSIONAL COMPUTED TOMOGRAPHIC RECONSTRUCTION

Abstract

Purpose: To evaluate femoral head coverage with three-dimensional computed tomographic (3D CT) reconstruction after Pemberton’s pericapsular osteotomy with open reduction in cases with developmental dysplasia of the hip (DDH).

In a prospective study, routine anteroposterior (AP) radiographs and 3D CT reconstruction of the pelvis in 15 consecutive patients with DDH were obtained pre-operatively and six months after surgery. In all patients, a Pemberton’s pericapsular osteotomy with open reduction was performed. The mean age of the patients at the time of surgery was 26 months (range 18 to 34) and 32 months (range 24 to 40) months at the last follow-up. Twelve of the patients were girls and three were boys. The 3D images were studied by using the anterior, posterior, lateral, and inferior views to analyse changes in the acetabular position in the frontal, sagittal, and trns-verse planes. Acetabular indices on radiographs and anterolateral acetabular lip angle (ALAL) on anterior view, posterolateral acetabular lip angle (PLAL) on posterior view, lateral acetabular inclination (LAI) on lateral view, and transverse rotation of the acetabulum (TR) on inferior view were measured pre- and postoperatively. Furthermore, coverage of the femoral head was classified according to Azuma’s criteria on anterior and posterior views.

The mean acetabular index was 38 degrees (range 33 to 52) preoperatively and 19 degrees (range 16 to 23) postoperatively. Comparison between pre- and postoperative 3D CT reconstruction images revealed increased acetabular adduction and extension, and decreased ace-tabular anteversion in all cases. Sufficient coverage of the femoral head was documented in all patients. Pre- and postoperative mean measurements on 3D CT reconstruction images are as follows: ALAL, 33 (range 29-40) – 16 (range 14-20); PLAL, 49 (range 46-52) – 29 (range 26-31); LAI, 48 (range 40-64) – 27 (range 25-30); TR, 13 (range 9-15) – 6 (range 5-10). Coverage of the femoral head was grade I in all patients according to Azuma’s criteria.

Conclusions: Pemberton’s pericapsular osteotomy provides successful results in appropriate cases, with sufficient coverage of the femoral head. However, if there is any doubt, utilisation of 3D CT reconstruction images may contribute to a more precise evaluation of the outcome.