The objective of this study was to evaluate the diagnostic accuracy of Tc-99m-labeled antigranulocyte antibody Fab′ fragments in infected total arthroplasty.
A total of 38 immunoscintigrams were evaluated retrospectively with 15 to 25 mCi Tc-99m-labeled antigranulocyte antibody-Fab′ fragments. The final diagnosis was assessed by articular puncture or intraoperative sampling.
In the total hip replacement group the authors found 10 true positives, 7 true negatives, 8 false positives, and 1 false negative; and in the total knee replacement group they found 4 true positives, 8 true negatives, and no false positives or false negatives. They also found a sensitivity of 93%, a specificity of 65%, and a positive predictive accuracy of 63%. There was a negative predictive accuracy of 94%.
The high negative predictive accuracy in the whole group suggests that the scan can be used to exclude infection in most cases. Negative results with a high clinical suspicion merits further investigation. A positive result will require further correlative imaging, especially for total knee replacement.
From the St. Josef Hospital, University Hospital, Department of Radiology and Nuclear Medicine, Bochum, Germany.
Received for publication March 10, 2004; accepted April 12, 2004.
Reprints: Thomas von Rothenburg, MD, St. Josef Hospital, University Hospital, Department of Radiology and Nuclear Medicine, Gudrunstraβe 56 - 44791 Bochum, Germany. E-mail: firstname.lastname@example.org