Proposal of a novel predictive radiological method to assess the possibility of closed reduction in late presenting developmental dysplasia of the hip: the femoro-acetabular zones.

Late presentation of developmental dysplasia of the hip (DDH) remains a major orthopedic problem. However, existing management is not standardized and is highly surgeon dependent. The theory behind femoro-acetabular zones (FAZ) system is to find a relationship between acetabular maturity and severity of dislocation in one hand, and the outcome of closed reduction, on the other hand in late presenting cases. A retrospective study was performed on children with untreated DDH that underwent closed treatment. Our series consisted of 65 hips; mean patient age was 24 months (range: 9-30 months) with a minimum follow-up of 3 years. FAZ classification was applied to the pre-reduction pelvic radiograph, while the results were evaluated according to Severin's scoring system. Overall, 37 of 65 hips (57%) achieved a satisfactory outcome (Severin I and II), while 22 hips (33%) were found to be unsatisfactory (Severin III). Six hips (10%) needed an open reduction. FAZ expressed a simple and reliable classification in predicting the success of closed reduction. This novel X-ray-based classification system can easily predict patients with DDH in whom a closed reduction is likely to succeed and defer patients with higher grades to surgical intervention. Yet, its validity has to be verified in larger cohort studies and directly compared to the established International Hip Dysplasia Institute classification.