The evolving slope of the proximal femoral growth plate relationship to slipped capital femoral epiphysis.

We measured the physeal angle (slope) of the proximal femoral physis on the standard anteroposterior (AP) radiographs. Controls consisted of 307 hips in children aged 1-18 years. Similar measurements were made on the affected (slip) and unaffected (nonslip) sides of 107 children with manifest unilateral slipped capital femoral epiphysis. An age-related increase of 14 degrees occurs in the slope of the proximal femoral physis between ages 1 and 18 years, with maximal increase between ages 9 and 12 years. Increasing obliquity of the proximal femoral physis may be yet another factor contributing to slipped capital femoral epiphysis.