Femur remodelled during growth after osteomyelitis causing coxa vara and shaft necrosis

A case of osteomyelitis of the femur in a 6-year-old boy, which resulted in pathological fracture of the femoral neck, severe coxa vara deformity, and total sequestration of the diaphysis, is reported. Sequestrectomy was intentionally delayed until 10 months had elapsed from the onset of the disease in order to let an involucrum develop. At removal of the main sequestra, the involucrum was stable and had replaced the necrotic diaphysis. Pseudarthrosis was prevented by the delay of sequestrectomy. During 9 years of growth after the acute stage, the coxa vara deformity spontaneously corrected to a state close to normal anatomy and, at the age of 15 years, the shape of the entire bone was not far from normal. The almost complete restoration to the normal shape of the destroyed femur indicates that both the differentiation capacity of the cells from which it was restored and grew and the guiding forces directing their development had been preserved. Corresponding phenomena, still poorly understood, may play an important role in several pathological conditions of the growing skeleton.