The torsional basis for slipped capital femoral epiphysis.

Fifteen moderate to severe acute slipped capital femoral epiphyses were manipulated in 15 patients to correct significant deformities; in each case, torsion played a critical role in the reduction. Nine of 15 patients with acute slips underwent controlled, open reduction from the anterolateral approach, stabilizing the epiphysis while the metaphysis was internally rotated, flexed, and abducted; none had osteonecrosis or chondrolysis. The other 6 acute slips were treated with traction using internal rotation to achieve closed reduction; 2 of these 6 closed reductions progressed to osteonecrosis, and both were reduced in an uncontrolled situation. Of the 15 acute slips, 6 involved torsion as the primary force. Based on the importance of torsion in all the reductions and the prevalence of torsion as an etiologic factor in the initial slips, it is postulated that torsion is an important contributing component in the etiology of slipped capital femoral epiphysis. Despite 2 cases of osteonecrosis in unstable hips, these 15 manipulative reductions were 87% successful. If the 2 inadvertent closed reductions are eliminated, then the success rate is 100%.