Nuclear imaging in loosening of hip-joint endoprostheses.

In 28 patients with surgically proved loosening of hip-joint endoprostheses and 42 patients without loosening between 2 and 12 years after implantation and without clinical or radiological signs of loosening we performed clinical evaluation, and radiographs, a three-phase bone scan, and a 111indium-labeled leukocyte scan (ILLS). The sensitivity of radiographs in the group with loosening of hip-joint endoprostheses in the femoral as well as in the acetabular component was only about 50%, while the specificity was almost 100%. With a combination of radiographs and ILLS we reached a sensitivity in the acetabular component of 100% and in the femoral component of 88%, but specificities of only 57% in the acetabular component and 40% in the femoral component were found. We found that the ILLS is a very helpful method of examination to detect loosening of hip-joint arthroplasties in doubtful cases.