Late spinal infections are more common after pediatric than after adult spinal deformity surgery

Purpose To compare the incidence, timing, and microbiologic factors associated with late spinal infection (onset >= 6 months after index operation) in pediatric versus adult spinal deformity patients who underwent instrumented posterior spinal fusion (PSF). Methods We retrospectively queried our institutional database for pediatric (aged <= 21 years) and adult patients who underwent instrumented PSF from 2000 to 2015. Inclusion criteria were > 12-month follow-up, spinal arthrodesis spanning 4 or more levels, and idiopathic or degenerative spinal deformity. We included 1260 patients (755 pediatric, 505 adult). Incidence, timing, and microbiologic and operative parameters of late spinal infections were compared using chi-squared and Fisher exact tests. Alpha = 0.05. Results Late spinal infection occurred in 28 (3.7%) pediatric and 2 (0.39%) adult patients (p = 0.009). Mean onset of infection was 4.2 years (range 0.7-12) in pediatric patients and 4.0 years (range 0.7-7.3) in adults (p = 0.93). Pediatric patients underwent arthrodesis spanning more levels (mean +/- standard deviation, 10 +/- 2.0) compared with adults (8.4 +/- 3.3) (p < 0.001). Adults experienced greater intraoperative blood loss (2085 +/- 1491 mL) compared with pediatric patients (796 +/- 452 mL) (p < 0.001). Culture samples yielded positive growth in 11 pediatric and 2 adult cases. Propionibacterium and coagulase-negative staphylococci were the most commonly detected microorganisms in both cohorts. Conclusion Late spinal infections were significantly more common in pediatric patients than in adults after instrumented PSF for spinal deformity. Skin and indolent microorganisms were the primary identifiable causative bacteria in both cohorts.