Intrapelvic migration of the prosthetic acetabular component.

The authors propose a preoperative evaluation protocol for cases of dislocation of the prosthetic cup complicated by intrapelvic migration, obtained by studying 20 cases of prosthetic loosening with protrusion of the acetabular component in the pelvis, treated by reimplantation or explantation. In all of the patients, accurate preoperative planning was carried out, because of the considerable frequency of dislocation, compression or damage to the vascular and nervous structures deriving from migration inside the pelvis of the acetabular component. The authors suggest that in all cases of acetabular loosening evaluation involve standard X-rays, bone scan with technethium99 and with marked granulocytes, CT scan. When the cup protrudes in the pelvis, prior to surgery, CT scan with contrast medium will be required, and if the risk of vascular involvement exists, angiography should also be carried out.