Spica MRI predictors for epiphyseal osteonecrosis after closed reduction treatment of dysplasia of the hip.

Spica MRI with intravenous gadolinium contrast after closed reduction for developmental dysplasia of the hip (DDH) helps to determine successful reduction and attempts to identify patients at risk for epiphyseal osteonecrosis. The objective of our study was to evaluate spica MRI predictors for epiphyseal osteonecrosis after closed reduction. This was a retrospective study of all patients undergoing closed reduction for DDH followed by gadolinium-enhanced spica MRI between July 2011 and November 2014. Patient demographics and clinical follow-up through 2017, including the development of epiphyseal osteonecrosis and need for reintervention after the initial reduction, were recorded. MRI data included hip abduction angles and quantifying the percentage of femoral head enhancement. Twenty-five hips in 21 patients (16 girls, five boys, mean age: 0.99 years, range: 0.4-3.1 years) were included in our study. The mean follow-up period was 3 +/- 1.5 years (range: 0.65-6.1 years). Eight (32%) of 25 hips went on to develop osteonecrosis. Epiphyseal osteonecrosis was more likely with less than 80% enhancement (sensitivity 87.5%, specificity 88.25%, positive predictive value 78%, negative predictive value 94%). The mean contrast enhancement for patients developing osteonecrosis compared with those who did not was 37.5 and 86.5%, respectively; P = 0.001. Immediate postspica MRI with gadolinium is a useful prognostic tool for determining future risk for epiphyseal osteonecrosis in children treated for DDH. Our data complement existing literature and suggest that even in cases with partial epiphyseal enhancement, osteonecrosis may still develop. When the epiphyseal enhancement is less than 80%, it is recommended that spica cast revision is considered.