Polyclonal, nonspecific In-111-IgG scintigraphy in the evaluation of complicated osteomyelitis and septic arthritis

Background. In this investigation we tested the hypothesis that In-111-IgG scintigraphy can differentiate infectious from sterile inflammatory process es in patients with complicated osteomyelitis or septic arthritis. Methods. A prospective university hospital based study was performed over 1 8 months. We studied 31 sites of suspected infection, in 25 adult patients, (age 18 to 74 years, 12 females and 13 males) referred with clinical prese ntations compatible with complicated osteomyelitis or septic arthritis and in whom proof of the infection was likely to be obtained. The clinical sett ing in these patients was previous trauma, recent surgery, peripheral vascu lar disease or adjacent soft tissue infection. Whole body scintigraphy was performed at 1-6, 18-24 and 42-48 hours after administration of 55 MBq of I n-111-IgG and results were compared to radiographs, Tc-99m-MDP skeletal sci ntigraphy, biopsy specimens (9 sites) or synovial fluid aspirates (4 sites) and clinical follow-up, Results. Of the 31 sites evaluated, 68% (21/31) were interpreted as negativ e for abnormal tracer accumulation and 32% (10/31) were considered positive . In patients who underwent biopsy and/or synovial fluid aspiration, 6 of 7 sites were correctly interpreted as positive; sensitivity 86%, Five of 6 s ites were correctly interpreted as negative; specificity 83%, When all pati ents were considered using clinical follow-up in addition to culture result s, 9 of 10 sites were correctly interpreted as positive (sensitivity 90%) a nd 20 of 21 patients were correctly interpreted as negative (specificity 95 %). Conclusions. In-111-IgG scintigraphy is useful for detection of musculoskel etal infection Ln patients in whom sterile inflammatory events simulate inf ectious processes.