Chronic staphylococcal osteomyelitis: an experimental model.

Chronic osteomyelitis continues to be a serious clinical problem. For example, despite antibiotic treatment, chronic osteomyelitis has been observed to develop in 15 to 29 percent of patients with acute hematogenous osteomyelitis (1, 2). Chronic osteomyelitis has been noted to develop with greater frequency in patients with osteomyelitis secondary to postoperative infection, i.e., particularly in patients undergoing open reduction including internal fixation of fractures (1, 3-6). Little is known about the pathogenesis of chronic osteomyelitis, particularly those predisposing factors which might be more likely to lead to the development of a chronic rather than an acute lesion. The lack of a good experimental model for human osteomyelitis is most certainly responsible, at least in part, for the slow progress of investigative efforts into this serious disease. It is well known that chronic osteomyelitis of a long bone is a difficult lesion to produce in laboratory animals (7). Most animals will die within a few weeks after inoculation of bacteria into bone or else they will rapidly clear the bone marrow of infection. A number of investigators (3, 7, 8, 9) were able to produce acute osteomyelitis in experimental animals but, other than Mitra (9), were either unable to keep their animals alive, or did now show that the acute process became chronic. Recently Norden (10), employing a model initially described by Scheman and colleagues (7), reported observations on infected rabbit tibias over 180 days. To our knowledge, no one has maintained an active infection for longer periods. The present report describes our observations on a model of chronic staphylococcal osteomyelitis maintained in the rabbit tibia for periods up to one and one-half years. The pathologic and radiologic appearance of the present model is similar