Evaluation of graft-host bone interactions after failed vascularized fibular grafting of femoral head necrosis may elucidate the reasons for failure of the procedure. According to the authors' study, the vascularized fibula implanted into the femoral head before collapse has the potential for restructuring the major segment of the affected head and delaying joint degeneration for many years if circumferential graft-host union is established. Asymmetric bone healing and non-union between the graft and the necrotic subchondral bone in the weight-bearing area lead to failure, progression of symptoms, and subsequent early hip replacement.