Bending hip pain may be caused by lumbar disc herniation, pyriformis syndrome, hip synovitis and other factors. 1. Lumbar disc herniation: it is related to disc degeneration, heredity, injury, lumbar spine development abnormality and other factors. Symptoms such as lumbar pain, radiating pain in the lower limbs, and pain in the buttocks when bending over can occur in some patients. 2. Piriformis syndrome: Piriformis syndrome is mainly caused by the sciatic nerve compression in the region of the piriformis muscle. It is often manifested as buttock pain, pain can be radiated along the sciatic nerve, bending, sitting cross-legged, lifting weights may lead to pain aggravation. 3. Hip synovitis: Hip synovitis may be caused by infection, trauma, injury and other factors. The main manifestation of hip pain, swelling, can be in bending over to aggravate the symptoms of pain, manifested as bending buttock pain. There are more causes of bending hip pain, it is recommended to go to the hospital in time to identify the cause. At the same time, for the cause of the disease with the doctor to take relevant treatment measures.