There are usually three causes of pain in the buttocks and thigh connection bones: first, sciatic nodule bursitis, if when sitting on a stool, especially when doing a hard stool, there will be pain in the hip and hard stool contact areas, most belong to the sciatic nodule bursitis, differential diagnosis, let the patient lie on his back, check with his hands on the buttocks to a hard bone, press to feel something cystic underneath, and pain when pressed hard is Sciatic nodule bursitis. Second, femoral head necrosis, femoral head necrosis can also occur in the buttocks and thigh root pain. The third, lumbar disc herniation compression sciatic nerve, can also appear buttocks and thigh bone pain, these three cases of specific how to identify the hospital by the doctor to check touch, pressure or check the CT, MRI clear diagnosis.