Wound Complications

Prevalence

Contemporary antisepsis and antibiotics have dramatically reduced the prevalence and morbidity of SSIs across all disciplines. Spine surgery is no exception, with wound infection rates as low as 0.2% and 1.6% reported in the anterior cervical setting. In a reported series, 132 of 3174 (4.2%) patients undergoing any spinal procedure developed infection. At the authors’ center, acute SSIs complicated only 1.0% of 1001 consecutive posterior cervical cases. Despite these low figures, SSI is one of the most common adverse events in spine surgery. Furthermore, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) is rising, thus making risk factor modification invaluable.

Demographic and Medical Risk Factors

Alcohol consumption, cigarette smoking, and intravenous drug abuse represent behavioral risk factors for SSI. Smoking intervention even a month before the surgical procedure may prove beneficial. Indwelling venous catheters serve as reservoirs for nosocomial organisms. To diminish such colonization, patients hospitalized for extended periods may be allowed to return home before elective procedures. Trauma victims and those admitted to an intensive care unit are at high risk, but their medical status often obviates interim discharge. Fortunately, the comorbidities associated with trauma can be addressed. Most importantly, active infection should be treated as long as the spinal disorder permits.

Ironically, both malnutrition and obesity predispose patients to SSI. Because malnutrition hampers antibody production, hyperalimentation is an attractive preventive measure. A lymphocyte count lower than 1500 mm ⁻³ , albumin lower than 3.5 g/dL, or transferrin lower than 226 mg/dL should raise concern. The role of obesity is less clear. Whereas the dissection required for a corpulent neck entails a wide field for inoculation, adipose tissue is relatively immunoprivileged. Despite these mechanisms, the correlation of body mass to infection is perhaps more aptly described by comorbidity. The glucose level of uncontrolled diabetes (>200 mg/dL) retards leukocyte function and has been linked to a variety of complications including SSI. Optimizing glucose concentrations preoperatively is ideal.

Intuitively, immunosuppression augments the likelihood of infection. Causes include certain malignant diseases, cancer chemotherapeutics, drugs to combat graft-versus-host disease, and acquired immunodeficiency syndrome with a CD4 count lower than 200 mm ⁻³ or a viral load greater than 10,000 mL ⁻¹ . Rheumatoid arthritis is an especially relevant medical risk factor. The disease itself promotes cervical instability, and antirheumatic agents hinder wound healing. Tapering of iatrogenic causes of immunosuppression and dehiscence demands careful risk-to-benefit discussions, often with an internal medicine specialist. For instance, an approximately 2-month window (6 weeks before and 2 weeks after surgical procedures) exists around which radiation therapy may be scheduled to maximize healing.

Radiation therapy and prior spine operations also increase scar tissue and intraoperative hemorrhage, which predisposes to hematoma. This can cause airway compression and serve as a nidus for infection. Evidence for the use of antifibrinolytic agents in major spine surgery has accumulated, although these agents are seldom indicated in the cervical surgical setting. Moreover, hypervascular tumor embolization may be appraised before resection.