Slipped capital femoral epiphysis: physeal histologic features before and after fixation.

Physeal histopathologic changes following slipped capital femoral epiphysis (SCFE) are usually considered permanent. This assumption may not be correct, since radiographic signs of proximal femoral neck growth and remodeling are commonly seen after fixation. This work analyzed the physeal histologic features of chondroepiphyseal biopsies before and after SCFE surgical fixation but before complete physiologic epiphysiodesis. Eighteen patients, nine with unstable and nine with stable SCFE of varying severity, had pretreatment biopsies. Three patients had postfixation biopsies prior to total physiologic proximal femoral epiphysiodesis. Pretreatment biopsies showed varied degrees of histoarchitectural changes ranging from almost normal arrangement to markedly deranged physeal morphology. Postfixation biopsies showed improved physeal organization in a case of moderate unstable SCFE. In one severe unstable case and one severe stable case, nearly normal physeal architecture was seen. Physeal histopathologic changes appear to improve after fixation. Progressive modulation of the recovering physis after fixation helps explain the remodeling and growth changes seen radiographically after chondroepiphyseal fixation.