Background: The purpose of this study was to investigate residual acetabular retroversion after skeletal maturity in patients with Pemberton osteotomy.
Patients and methods: We compared 40 hips in 36 patients treated with a Pemberton osteotomy (Pemberton group) and 30 hips in 26 patients treated only with a Pavlik harness (Rb group) for developmental dysplasia of the hip. The average age at operation in the Pemberton group was 94.5 months and the follow-up duration was 151.8 months. Radiographic parameters included the acetabular index (α angle) and the center-edge angle of Wiberg, preoperatively and at skeletal maturity. We examined the crossover sign (COS) at the latest follow-up as a sign of acetabular retroversion (AR). We compared the parameters between the two groups and examined the risk factors for acetabular retroversion using a multivariate Cox model.
Result: A COS (+) was significantly more frequent in the Pemberton group compared to the Rb group [15 hips (37.5%) vs 3 hips (10%); p = 0.0077]. In the Pemberton group, the average age at operation in COS (+) hips was significantly older than that in COS (-) hips (126.9 vs 72.8 months; p = 0.0005). The preoperative α angle did not vary between hips with and without COS; however, the postoperative α angle was significantly smaller in COS (+) hips. A multiple logistic regression analysis for prediction of COS (+) showed that the age at operation and the amount change of α angle were significant predictors for COS (+) hips. The cut-off of the age at operation was 7 years and 9 months old.
Conclusions: AR was present in 37.5% of the hips in the Pemberton group after skeletal maturity. Remodeling of acetabular version was observed in younger patients; however, hips in older patients (>8 years) at the time of operation and greater degrees of correction tended to result in AR.