A computer model of slipped capital femoral epiphysis. Causes of fixation error and chondrolysis.

Penetration of the joint by metal pins can occur when treating slipped capital femoral epiphysis. Predisposing factors are present in the usual surgical methods. These include x-ray detail loss secondary to the pelvic projection and failure to obtain specific x-ray orientation to the axis of the capital epiphysis. One operative strategy to reduce these predispositions is presented. A probable mechanism of how chondrolysis can occur without joint penetration following extra capsular osteotomy is described with a theoretical remedy. Computer disease modeling and treatment simulation are the basis of this study. The computer model, which closely simulates all degrees of the disease, suggests that SCFE deformation is caused by hip extension against anterior hip capsule contracture. The latter is also the proposed cause of chondrolysis following realignment procedures.