Prevalence of allograft contamination during intraoperative processing for spinal deformity correction surgery

Study Design: Prospective study. Objectives: To prospectively evaluate bone allografts during spinal fusion surgery for 1) the rate of contamination as a result of perioperative preparation, and 2) the types of bacterial organisms that may be transmitted through the contaminated bone allograft. Summary of Background Data: Bone allografts are routinely used to enhance spinal arthrodesis procedures. Ready availability and lack of donor site morbidity make them valuable alternatives to iliac crest bone grafts. Reports of disease transmission of such organisms as hepatitis C, the human immunodeficiency virus, and a variety of bacterial pathogens through allograft bone implants raise concerns for patient and practitioner safety. Methods: Our study population consisted of 50 consecutive (20 male and 30 female) patients (mean age at surgery, 15 years; range, 3-51 years) undergoing spinal deformity correction from May 2010 through October 2010, by 1 surgeon at 1 institution. The mean operative time was 297 minutes (range, 81-444 minutes), and the most commonly fused spinal levels were T5 to L4. During the procedure, the researchers prospectively obtained intraoperative microbial culture swabs from a container with freeze-dried allograft and from an empty identical control container. Aerobic and anaerobic bacterial culture growth was assessed for 7 days postoperatively. Each patient was observed for 6 weeks after surgery to ascertain any evidence of surgical-site infection. Results: Microbial cultures showed bacterial growth in 4 cases: 1 allograft specimen (day 4, very light Staphylococcus aureus) and 3 control specimens (day 3, very light Enterococcus; day 4, very light S aureus; and day 6, Propionibacterium acnes). No patient showed signs of infection in the perioperative or 6-week postoperative period. Conclusions: Intraoperative allograft preparation is not a major source of bone allograft contamination during spinal surgery.