Screwed bush for socket of hip joint prosthesis - has hand of screw thread chosen so that bush tends to tighten in use

摘要

The hip joint endoprosthesis has a socket (2,7) which is screwed into the pelvic bone (1). The hand of the screw thread is so chosen that the turning moment exerted on the bush, during use, tends to tighten the bush. That is when the patient is walking and the endoprosthesis bears the weight of the patient and the femur rotates relative to the pelvis. This effect is achieved by providing the right leg bush with a right-hand screw thread and providing the left leg bush with a left-hand thread. ADVANTAGE - The bush is prevented from becoming loose in its socket.