Outcome and treatment of postoperative spine surgical site infections: predictors of treatment success and failure.

Background: Surgical site infection (SSI) is an important complication after spine surgery. The management of SSI is characterized by significant variability, and there is little guidance regarding an evidence-based approach. The objective of this study was to identify risk factors associated with treatment failure of SSI after spine surgery.

Patients And Methods: A total of 225 consecutive patients with SSI after spine surgery between July 2005 and July 2010 were studied retrospectively. Patients were treated with aggressive surgical debridement and prolonged antibiotic therapy. Outcome and risk factors were analyzed in 197 patients having 1 year of follow-up. Treatment success was defined as resolution within 90 days.

Results: A total of 126 (76 %) cases were treated with retention of implants. Forty-three (22 %) cases had treatment failure with five (2.5 %) cases resulting in death. Lower rates of treatment success were observed with late infection (38 %), fusion with fixation to the ilium (67 %), Propionibacterium acnes (43 %), poly microbial infection (68 %), >6 operated spinal levels (67 %), and instrumented cases (73 %). Higher rates of early resolution were observed with superficial infection (93 %), methicillin-sensitive Staphylococcus aureus (95 %), and <3 operated spinal levels (88 %). Multivariate logistic regression revealed late infection was the most significant independent risk factor associated with treatment failure. Superficial infection and methicillin-sensitive Staphylococcus aureus were predictors of early resolution.

Conclusion: Postoperative spine infections were treated with aggressive surgical debridement and antibiotic therapy. High rates of treatment failure occurred in cases with late infection, long instrumented fusions, polymicrobial infections, and Propionibacterium acnes. Removal of implants and direct or staged re-implantation may be a useful strategy in cases with high risk of treatment failure.