Chapter 5

Osteomyelitis of the spine comprises approximately 1% of all cases of pyogenic skeletal infections. Pathogenic organisms can infect the vertebra, the intervertebral disk, or the spinal canal through multiple mechanisms, including local spread from an adjacent infection or as a result of seeding from a noncontiguous source of infection either hematogenously or through the lymphatics. Bacteria can also be introduced directly to compromised tissues as a result of trauma, surgery, diskography, or intravenous or intradural catheterization. Although many organisms are implicated, the most frequently cultured organisms are Staphylococcus aureus and Pseudomonas aeruginosa. Salmonella should be strongly considered as a potential pathogen in patients with sickle cell disease. Infection with Mycobacterium tuberculosis is often seen in less developed countries and in prison populations. Spinal sepsis is most common in adolescents, the elderly (more than 60 years), intravenous drug abusers, patients with diabetes or renal failure, and patients who have undergone spinal surgery. Osteoporosis is also implicated as a predisposing factor secondary to increased blood flow. Eismont and Bohlman reported several risk factors for neurologic deterioration including patients with diabetes, rheumatoid arthritis, steroid use, age greater than 50 years, a cephalad level of infection, and infection with S. aureus. For additional information on osteomyelitis, see Chapter 8.

Clinical Findings

Symptoms and Signs

Patients with osteomyelitis of the spine may or may not present with symptoms relating to their spine. Pyogenic osteomyelitis is fundamentally different from tubercular osteomyelitis. In the latter, patients generally complain of indolent, chronic back pain. In pyogenic osteomyelitis, the symptoms of acute spontaneous back pain, fever, and weight loss are common but not always present. On physical examination, patients with diskitis or pyogenic osteomyelitis of the spine often exhibit significant percussion tenderness posteriorly over the affected vertebral segments. Paraspinal muscle spasm may be seen in more than 90% of patients. A history of fevers is found in less than 50% of affected patients. Neurologic involvement, fortunately, affects less than 10% of all patients with spinal infections. When the infection involves the cervical spine, patients may develop Horner syndrome, or dysphagia. Pyogenic osteomyelitis should be suspected in any patient who presents with back pain and a recent history of an acute systemic infection (eg, appendicitis, perinephritic abscess, pneumonia, genitourinary tract infection, or meningitis).

Laboratory Studies

The results of laboratory tests can be equivocal. The white cell count is elevated in only 42% of patients and often is normal. Both blood and spinal cultures may also be negative. Blood cultures are accurate in only 25% of cases, and closed biopsy techniques are diagnostic in only 70% of cases. The ESR rate is elevated in more than 90% of patients, and the C-reactive protein level (CRP) is also elevated at an earlier point in the infectious process. However, both of these tests are systemic indicators of inflammation and are relatively nonspecific. Thus, there is often a significant delay in diagnosis ...

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