Risk factors for osteomyelitis.

An approach that is useful in classifying the risk factors for the development of acute osteomyelitis is the same as one commonly employed to discuss the mechanisms responsible for pathogenesis: hematogenous dissemination, direct inoculation, and contiguous spread from an adjacent area of soft tissue infection. Acute hematogenous osteomyelitis is predominantly a disease of children. Factors that favor the development of acute bone infection are those that predispose to bacteremia. These include indwelling intravascular catheters, distant foci of infection, and intravenous drug abuse. The distant sites of focal infection that are most commonly associated with acute osteomyelitis include the skin as well as urinary and respiratory tracts. Two patient groups with an usual susceptibility to acute skeletal infections are those with sickle cell anemia and chronic granulomatous disease. The second major mechanism for the development of acute osteomyelitis is by direct inoculation. Injuries due to penetrating bites and puncture wounds of the food may serve to infect bone directly. Diagnostic procedures (lumbar puncture, fetal monitoring electrodes, suprapubic aspiration, and heel sticks) may result inadvertently in the inoculation of a neighboring osseous structure. Surgical procedures such as internal fixation of long bone fractures and skeletal traction may cause an infection of the bone. Osteomyelitis may develop as a consequence of contiguous spread of infection from adjacent soft tissue, particularly if vascular insufficiency complicates the clinical picture. Infection of the mandible, maxilla, and frontal or mastoid bones may result from persistent or neglected infection of the teeth, paranasal sinuses, or middle ear cavity, respectively. The major risk factor for chronic infection of bone is inadequate or delayed management of acute osteomyelitis or completely unrecognized bone infection.