Surgical-site infection following spinal fusion: a case-control study in a children's hospital.

OBJECTIVES: To determine the rates of surgical-site infections (SSIs) after spinal surgery and to identify the risk factors associated with infection. DESIGN: SSIs had been identified by active prospective surveillance. A case-control study to identify risk factors was performed retrospectively. SETTING: University-associated, tertiary-care pediatric hospital. PATIENTS: All patients who underwent spinal surgery between 1994 and 1998. Cases were all patients who developed an SSI after spinal surgery. Controls were patients who did not develop an SSI, matched with the cases for the presence or absence of myelodysplasia and for the surgery date closest to that of the case. RESULTS: There were 10 infections following 125 posterior spinal fusions, 4 infections after 50 combined anterior-posterior fusions, and none after 95 other operations. The infection rate was higher in patients with myelodysplasia (32 per 100 operations) than in other patients (3.4 per 100 operations; relative risk = 9.45; P <.001). Gram-negative organisms were more common in early infections and Staphylococcus aureus in later infections. Most infections occurred in fusion involving sacral vertebrae (odds ratio [OR] = 12.0; P =.019). Antibiotic prophylaxis was more frequently suboptimal in cases than in controls (OR = 5.5; P =.034). Five patients required removal of instrumentation and 4 others required surgical debridement. CONCLUSIONS: Patients with myelodysplasia are at a higher risk for SSIs after spinal fusion. Optimal antibiotic prophylaxis may reduce the risk of infection, especially in high-risk patients such as those with myelodysplasia or those undergoing fusion involving the sacral area.