O1155 DIAGNOSIS OF SEPTIC LOOSENING OF TOTAL HIP ARTHROPLASTY WITH LABELED MONOCLONAL ANTIBODIES (LEUKOSCAN)

Abstract

Aims: To evaluate the value of 99mTc-labeled mono-clonal Fab antibodies (Leukoscan) in the diagnosis of septic loosening of total hip arthroplasty (THA). Methods: 16 patients (mean age 63.2 years) with hip arthroplasty (5 hemi,9 cementless,2 cemented THAs) were investigated for deep infection with the use of Leukoscan. Patient selection was based on a “high-risk protocol”. All patients were clinically evaluated using modified HHS and each patient’s workout included x-rays, WBC, ESR, CRP, dynamic bone scan 99mTc-MDP and Leukoscan. Two (2) patients were treated by wide debridement and continuous lavage,6 with revision surgery and 8 with Girdlestone. Histologic samples and cultures were received and their results were compared with Leukoscan’s findings. Results: Preoperative evaluation of the patients revealed as major risk factors:pathologic blood tests (16), previous surgical interventions (13), implant loosening (8), wound infection (7). Mean mHHS was 58 (28–80), mean ESR 51 (23–87 mm/h), mean CRP 4,1 (0,9–18 mg/dl). Bone scans were evaluated as 15 positive and 1 negative and they were matched with 15 positive and 1 negative Leukoscan respectively. Twelve (12) positive histopathologic results and 2 positive tissue cultures were matched with 14 positive Leukoscans, while 1 positive Leukoscan was not verified by positive histopathologic findings of chronic infection. Bacteriae identified were: S.epidermidis 5x, S.aureus 2x, Escherichia Coli 1x, S.saprophyticus 1x, Klebsiella pneumoniae 1x. Conclusions: Leukoscan seems to offer a reliable diagnostic tool for investigation of septic bone infection in presence of hip arthroplasty, presenting a senstitivity of 100% and spesitivity of 93,75%. Proper patient selection, based on diagnostic criteria and risk factors is essential.