Left thigh with buttock pain refers to the left hip pain, common causes are physiological reasons, trauma, necrosis of the femoral head, synovitis of the hip joint and so on. 1. Physiological reasons: because of long-distance running, playing soccer, basketball and other sports, the accumulation of lactic acid in the muscle or hip joint transient synovial edema, can appear pain, is a normal phenomenon, rest can be relieved. 2. Trauma: Most people have a history of trauma, due to violence caused by the skin around the left hip joint, subcutaneous tissue damage or hip bone, femur fracture, resulting in pain. 3. Femoral head necrosis: ischemic necrosis of the femoral head due to prolonged use of hormones, alcoholism, femoral neck fracture, etc., which increases the load on the femoral head when standing up and causes pain in the hip joint. 4. Hip synovitis: due to poor posture, chronic strain, trauma and other reasons, resulting in synovial inflammation of the hip joint, can also appear in the left hip pain. The causes of left hip pain are more, may also be related to sacroiliitis, ankylosing spondylitis, lumbar disc herniation, pyriformis syndrome, osteoporosis and other diseases, if the symptoms continue to be unrelieved, it is recommended to consult a doctor in time, to clarify the cause of the disease, and to carry out targeted treatment.