Assessing Avascular Necrosis Risk and Outcomes After Open Reduction for Developmental Dysplasia of the Hip in Children.

Background Avascular necrosis (AVN) of the femoral head is a serious complication after surgical treatment of developmental dysplasia of the hip (DDH). The main objective of this study is to identify the incidence of AVN and to define AVN risk factors. The study also aims to identify the effects of AVN and other factors on final clinical and radiological outcomes. Methods All patients in the study were managed according to King Saud University protocol for surgical treatment of DDH. Occurrence of AVN was reported. All affected hips were evaluated clinically and radiologically after six and 12 months and at final follow-up. Significant variables from the univariate analysis were entered into multivariate regression models. Results A total of 131 patients were included in the study involving 189 hips with DDH. AVN was diagnosed postoperatively in 23 (12%) hips. In the multivariate regression analysis, the presence of AVN (p=0.002), prolonged casting (p=0.016) and the need for a second surgery (p=0.029) were strong determinants of unsatisfactory clinical outcomes. Worse radiological outcomes were significantly associated with the presence of AVN (p=0.002), previous trials of closed reduction (p=0.032) and the need for a second surgery (p=0.013). In the last multivariate regression model, a previous trial of closed reduction (p=0.001), absence of an ossified femoral head (OFH) (p=< 0.001), prolonged casting (p=0.038), and the need for second surgery (p=0) were strong risk factors for AVN. Conclusions The current study highlighted the factors responsible for AVN occurrence after open DDH reduction. The factors which are strong determinants of unsatisfactory clinical and radiological outcomes were identified. Overcoming these factors is mandatory to improve the results.