Reconstruction of the sacral defect caused by tumor resection with bilateral gluteus maximus (GLM) adipomuscular sliding flaps. A huge defect is left after sacral tumor resection (a). Separation of the GLM adipomuscular flap on one side (b). Separation of another side of the GLM adipomuscular flap (c). The defect is eliminated by advancement of the bilateral GLM adipomuscular flaps (d).