Open reduction, capsulorrhaphy & acetabuloplasty (ORCA): A one stop surgical treatment for infant DDH

Nic Uren, Alex Aarvold, Amanda Rhodes, S Penker, Edward Lindisfarne, Kirsten Elliot, Nicholas Clarke

University Hospital Southampton

This study reports the longer-term outcomes of the Open Reduction Capsulorrhaphy Acetabuloplasty (ORCA) procedure, utilising a minimal outer table acetabuloplasty, which aims to stimulates acetabular growth and avoid later pelvic osteotomies.

The outcomes for 100 infants treated with ORCA, with a minimum of four year follow up, were analysed. Pre-operative patient demographics and radiological measurements were recorded. Radiological outcomes including IHDI classification, Acetabular Index (AI) and Severin grade were recorded at pre-defined post-operative intervals. The % of hips requiring further pelvic surgery was calculated. Operated hips were then compared to normal contralateral hips

The median age at the time of surgery was 15 months. Pre-operative dislocation severity was IHDI grade IV (high dislocation) in sixty cases, grade III in 28 and grade II in twelve cases. Mean pre-operative AI was 40° deg. This showed statistically significant improvements year on year (Repeated measures ANOVA, post hoc Bonferroni correction, p<0.001).
Mean AI at final follow up (range 4-12 years) was 18°, compared to 15° in the normal contralateral hips. 94% of cases have Severin Grade 1 (excellent) or 2 (good) outcome. Only 2% of patients required later pelvic osteotomy for residual acetabular dysplasia, compared to 60% of cases who do so after surgical reduction without pelvic osteotomy.

This procedure, utilising a minimal acetabuloplasty, appears to be at least as effective as open reduction and any formal pelvic osteotomy. The acetabuloplasty is technically quicker to perform, is far less invasive, and is therefore a simple adjunct for the surgeons.