Intact versus Fragmented 99mTc-Monoclonal Antibody Imaging of Infection in Patients with Septically Loosened Total Knee Arthroplasty

OBJECTIVE: This prospective study compared the diagnostic accuracy of imaging using an intact murine antigranulocyte antibody 99mTc-besilesomab, and a murine antibody Fab' fragment 99mTc-sulesomab, in patients with suspected septically loosened total knee arthroplasty. METHODS: Images from 20 patients who underwent three-phase bone scintigraphy followed by imaging using 99mTc-besilesomab (n= 10) or 99mTc-sulesomab (n= 10) were evaluated and compared. Final diagnosis was determined by microbiological evaluation of aspirated synovial fluid, intraoperative samples through the clinical course, or by long-term follow-up. RESULTS: Prosthesis infection was shown in 18 patients. At 4 and 24 h after intravenous injection, absolute uptake of 99mTc-besilesomab was significantly higher than 99mTc-sulesomab in infected knee joints. Infected-to-healthy knee activity ratios were similar at 4 and 24 h for 99mTc-besilesomab and 99mTc-sulesomab. CONCLUSIONS: Both 99mTc-besilesomab and 99mTc-sulesomab had similar diagnostic accuracy for the detection of septic arthroplasty. If repeated use of immunoscintigraphy is needed for follow-up, 99mTc-sulesomab should be preferred over 99mTc-besilesomab since it is known to be well tolerated and without side effects or incompatibility reactions.