Consider pyriformis syndrome, sacroiliac arthritis, femoral head necrosis, gluteal strain, etc. Pyriformis syndrome can be caused by traumatic injury or strain injury. 1. Piriformis syndrome: because of trauma or strain injury caused by the swelling of the piriformis muscle compression of the sciatic nerve can cause pain in the buttock depression, which can be radiates to lower limb pain and numbness. 2. sacroiliac arthritis: sacroiliac joint hyperplasia and degeneration, narrowing of the joint space caused by lumbosacral pain, swelling, can be involved in the buttocks on both sides of the pain. 3. Femoral head necrosis: bilateral ischemic necrosis of the femoral head can cause pain around the hip joints, pain on both sides of the buttocks, walking limp, and limitation of hip joint activities. 4. Gluteal muscle strain: often a position too long or often running and jumping caused by chronic strain and spasm of the hip muscles, causing pain on both sides of the buttock depression. If the depression pain on both sides of the buttocks persists without relief, it is recommended to go to the orthopedic department of the hospital for examination and treatment for the cause after a clear diagnosis.