Disease Information for Osteomyelitis: Definition

  • In children, osteomyelitis usually affects the metaphysis of the tibia or femur as well as growing bones with a rich blood supply; Infection of bone is produced by bloodborne organisms (hematogenous osteomyelitis); spread from infected tissue, including prosthetic joint infection; contaminated fractures; and bone surgery; Hematogenous

    osteomyelitis is most commonly caused by gram-positive organisms; Gram-negative organisms cause osteomyelitis in IV drug users, patients with sickle cell disease, and severely debilitated or traumatized patients; Fungi

    and mycobacteria tend to localize to bone, causing indolent chronic infections; Risk factors include debilitating comorbid disease, radiotherapy, cancer, diabetes, hemodialysis, and IV drug use; In children,

    any process causing bacteremia may predispose to osteomyelitis; Infection of bone is accompanied by occlusion of blood vessels, which causes bone necrosis and local spread of infection; Infection may expand through

    the bone cortex and spread under the periosteum, with formation of subcutaneous abscesses that may drain spontaneously through the skin; Patients with acute osteomyelitis of peripheral bones are usually febrile,

    have had weight loss and fatigue, and have localized warmth, swelling, erythema, and tenderness; Vertebral osteomyelitis produces localized back pain with paravertebral muscle spasm that is unresponsive to conservative treatment; Patients are usually afebrile;

    If treatment of acute osteomyelitis is only partially successful, low-grade chronic osteomyelitis develops with intermittent (months to many years) bone pain, tenderness, and sinus drainage; Chronic osteomyelitis is often

    polymicrobial; DX:In a patient with localized bone pain, fever and malaise suggest osteomyelitis; The WBC count may not be elevated, but the ESR and C-reactive protein usually are; X-rays become abnormal after 3 to 4 wk, showing bone

    destruction, soft tissue swelling, periosteal elevation, loss of vertebral body height or narrowing of the adjacent infected intervertebral disk space, and destruction of the end plates above and below the disk; If x-rays are

    equivocal, CT can define the abnormality and reveal paravertebral abscess formation; bone scan is helpful