Proximal Femoral Bone Cyst After Single Screw Fixation for Slipped Capital Femoral Epiphysis: A Case Report

An 11-year-old female patient underwent bilateral in situ fixation for slipped capital femoral epiphyses using single, cannulated, stainless steel screws. She presented 12 years later with a large osteolytic lesion of the proximal femur, which only involved 1 side. Histological evaluation showed a foreign-body reaction and synovial lining. Infection was ruled out and dynamic hip screw stabilization, and bone grafting were performed. The bone graft healed, and the hardware was removed to prevent a similar reaction. In retrospect, postoperative radiographs at 7 weeks showed subtle osteolysis along the screw.

Intra-articular drilling, vertical screw placement into the posterior epiphysis, and the prominent screw head may have led to this unexpected complication.