Although the many exogenous causes of osteomyelitis vary greatly, the resulting bone infections share some common characteristics. The bone becomes infected because the protective skin and periosteal barriers have been violated, allowing contamination of the bone. The infection usually persists because of the presence of necrotic soft tissue, necrotic bone, or a foreign body that serves as a nidus for continued bacterial proliferation.

Exogenous osteomyelitis can often be prevented immediately after an open fracture with early and thorough debridement of the contaminated and necrotic bone and administration of broad-spectrum antibiotics. Once established, exogenous osteomyelitis is very difficult to eradicate, and effective treatment requires surgical debridement of the infected necrotic bone, removal of infected foreign bodies (including implants), and long-term intravenous administration of bacteriaspecific antibiotics.

CHRONIC OSTEOMYELITIS

Bone infections are much more difficult to eradicate than soft tissue infections. Soft tissue cellulitis or abscess responds well to surgical drainage combined with the administration of appropriate antibiotics. However, simple surgical drainage combined with the administration of antibiotics may not eradicate chronic osteomyelitis. Bacteria become sequestered in the bone in areas where antibiotics cannot reach them in sufficient concentration owing to poor vascular penetration. A necrotic bone sequestrum or a fracture fixation device can act as a nidus for continued bacterial proliferation. Only removal of all of the necrotic bone and the foreign body can control the infection. This treatment often necessitates radical surgical debridement with removal of large segments of bone, creating significant mechanical instability and loss of function. In some patients, the infection can be fully eradicated only with amputation. Plates 8-7 and 8-8 depict two cases of chronic or recurrent osteomyelitis associated with unsuccessful plating of an open fracture and intramedullary rod fixation of a closed fracture.