Osteomyelitis of the Spine

Description:

• Constitutes 1% of pyogenic skeletal infections
• Pathogenic organisms can infect vertebral bodies, intervertebral discs, or the spinal canal
• Spine infected through local extension from adjacent infection or else from seeding of distant organ hematogenously or via lymphatic system
• Bacteria can be directly introduced by surgery, trauma, intravenous or intradural injection or catheterization
• Most frequently cultured organisms are:
• Staphylococcus aureus
• Pseudomonas aeruginosa
• Salmonella should be considered in patients with sickle cell disease
• Mycobacterium tuberculosis is seen in less developed populations and in prison populations (Pott’s disease)
• Spinal sepsis is common in:
• Adolescents
• Elderly
• IV drug users
• Patients with diabetes or renal failure
• Patients who have undergone spinal surgery
• Recent acute systemic infection, especially S.aureus
• Osteoporosis has been implicated as predisposing factor due to increased blood flow

Signs/Symptoms:

Pyogenic osteomyelitis

• Acute spontaneous back pain, +/- fever & weight loss
• Significant percussion tenderness posteriorly over affected vertebral segments
• Paraspinal muscle spasm in 90% of patients
• Fevers present in <50% patients
• Lab test results often equivocal
• Elevated WBC’s in only 42% patients
• ESR elevated in >90% cases but non-specific
• Diagnosis relies upon high index of suspicion

Imaging:

• Radiographic findings lag behind symptomatic progression of disease
• MRI with gadolinium contrast is gold standard for early detection
• Bone scan may be useful in diagnosis
• Plain radiographs often negative, late findings (10 days to 2 weeks) include disc space narrowing and endplate erosion
• Tubercular osteomyelitis: plain films demonstrate anterior vertebral body destruction with sparing of intervertebral disc

Treatment:

• Identification of responsible organism is key to treatment
• After confirmation of organism by blood culture or biopsy specimen, appropriate IV antibiotics administered for 6 weeks
• Short-term bed rest for pain management
• Successful nonoperative treatment most likely in patients < 60 years old, immunocompetent, infection by S. aureus, decreasing ESR as response to IV antibiotics
• Surgical treatment required to moderate advanced destruction of spine with instability, neurologic compromise, or failure to respond to IV antibiotics
• Surgical treatment consists of anterior debridement and stabilization with autologous structural bone grafting with possible posterior pedicle screw fixation and fusion
• Antibiotic impregnated polymethylmethacrylate cement may be used as a temporary spacer
• New minimally invasive techniques may prove to be excellent tools for management of spinal infections