Purpose: In slipped capital femoral epiphysis (SCFE) with increasing slip angle and increasing impingement, pain, stiffness, limping and degenerative change may follow. Currently there are no accepted guidelines to guide management in patients with stable SCFE. The main purpose of this study was to evaluate the proximal femoral geometry in stable SCFE using a postero-anterior radiograph of the hip in the extended position and to determine its use in predicting subsequent surgical management.

Methods: Over a 7 year period, we evaluated the proximal femoral geometry in a consecutive series of 31 adolescents with stable SCFE using the prone extension hip radiograph and statistically analysed the relationship between lateral slip angle (LSA), the morphology of the metaphyseal-epiphyseal (ME) junction, pain and hip range of motion.

Results: The mean age was 13.5 years and statistical analysis shows that ME anatomy is strongly related to LSA and pain. Linear regression analysis shows a strong significant relationship between LSA and hip range of movements.

Conclusions: The prone extension hip x-ray, is capable of accurately predicting the response to a flexion valgus intertrochanteric osteotomy and will clearly demonstrate the degrees of flexion and valgus required to restore the proximal femoral anatomy to allow a more functional range of motion by reducing impingement. The prone extension hip x-ray will also indicate when an additional cheilectomy may be required or alternatively define degrees of proximal femoral deformity which are beyond the scope of intertrochanteric osteotomy and in which a more radical correction at the epiphyseal-metaphyseal junction is required.

Significance: We found the prone extension hip radiograph useful in selecting those hips amenable to management by flexion valgus intertrochanteric osteotomy and other surgical Methods: