Femoral neck fracture secondary to in situ pinning of slipped capital femoral epiphysis: a previously unreported complication.

Two patients developed femoral neck fractures as a complication of in situ pinning for slipped capital femoral epiphysis (SCFE) by surgeons who each used a cannulated screw system. Both patients exhibited recurrent hip pain, femoral neck fracture, and coxa vara after asymptomatic postoperative intervals of 2 and 6 months, respectively. The fracture in one patient healed with weight relief alone: the other persisted, requiring a vascularized pedicle bone graft. Bone biopsy at surgery disclosed avascular necrosis (AVN). Based on preliminary studies of heat production during reaming, we speculate that these fractures developed through areas of AVN secondary to thermal injury.