Hip socket bone grafting. Diagram showing the second stage in hip socket bone grafting as part of a total hip replacement operation. A metal mesh liner has been placed in the acetabulum (hip socket) in the patient's pelvis. Defects in the bone are filled with vigorously impacted morsellised cancellous bone (impaction with a hammer shown here). This is followed by cementing of the socket implant (acetabular cup) into which the 'ball' of the femoral implant (not shown) fits. For a sequence showing the process, see images C016/6783 to C016/6786.