This occurs when there is a “collision” or contact between the femoral component and the acetabular one during movement. The problem may arise say if the artifical hip does not maintain the distance between the femur and the socket as there existed prior to the surgery. It may also arise if there are substantial remaining osteophytes around the socket. The osteophytes are “extra” bone that nature produces in joints that are athritic. These projections of bone may get in the way when the artifical hip is moving and cause the ball to lever out of the socket in certain positions.
The best treatment is prevention as far as possible and to remove the osteophytes at the time of the primary surgery. At times it is possible to correct the problem by realigning the components or by inserting a longer or larger ball component on the femur.