Experimental osteomyelitis: description of a canine model and the role of depot administration of antibiotics in the prevention and treatment of sepsis.

UNLABELLED

Osteomyelitis of the proximal portion of the tibia was consistently produced in the dog by the instillation of a suspension of Staphylococcus aureus about an intramedullary foreign body consisting of acrylic bone cement. The clinical, histological, and roentgenographic manifestations of the infectious process were consistent with those of subacute osteomyelitis, such as may be encountered in infections following total joint arthroplasty. The osteomyelitic process persisted in six of the seven tibiae even after removal of the acrylic bone cement. Using this model, gentamicin-impregnated acrylic bone cement (Palacos) prevented the development of osteomyelitis in nine of ten tibiae that were concomitantly exposed to Staphylococcus aureus in concentrations ranging from 1 x 10(3) to 1 x 10(9) organisms. However, Palacos in bulk form was ineffective in the treatment of three of five tibiae in which osteomyelitis caused by Staphylococcus aureus was already established.

CLINICAL RELEVANCE

A variety of new antimicrobial agents has been introduced, but evaluation of the value of these agents in infections of the musculoskeletal system has relied almost exclusively on clinical trials. Preclinical trials in an animal model could permit earlier detection of promising agents and proper dosage schedules. Newer surgical procedures utilized in the treatment of osteomyelitis, such as local muscle flaps and free vascularized flaps, could also be evaluated to determine how they influence the local blood supply and microbial persistence. In addition, the animal model might aid in the evaluation of newer and non-invasive diagnostic scanning techniques used in the study of infection.