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. Symptoms and Signs 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.
Chronic osteomyelitis is often polymicrobial.
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. Radioisotope bone scans are abnormal earlier than x-rays but do not distinguish among infection, fractures, and tumors.