Hip injury. X-ray of a patient's injured right hip. The thigh bone (femur) runs from bottom left to centre left. It has a ball-shaped end that fits into the socket of the hip (acetabulum). The acetabulum has been damaged, maybe by a dislocation or sprain. The head of the femur is pushing against the top of the socket. This causes pain and stiffness. Treatment is with anti- inflammatory drugs and physiotherapy.