Clinical Outcomes After Lumbar Fusion Complicated by Deep Wound Infection

Abstract

A propensity score-matched case-control study. To evaluate the 2-year clinical outcomes of patients who have undergone instrumented spinal fusions complicated by deep wound infections and compare them with a propensity score-matched control group who did not have infections. Postoperative infection after instrumented spinal fusion is a major complication, often resulting in substantial short-term morbidity. However, there is little literature reviewing how these patients do in the longer term after their infection has been managed. Thirty patients were identified who underwent instrumented lumbar spinal fusion with complete preoperative and 2-year postoperative outcome measures and had acute (#3 mo) postoperative deep wound infections necessitating irrigation and debridement. Outcome measures included the Oswestry Disability Index, 36-Item Short Form Health Survey Physical and Mental composite summaries, and numeric rating scales (0-10) for back and leg pain. A noninfected control group was identified using propensity score-matching techniques based on demographics, baseline clinical outcome measures, and surgical characteristics. Two-year postoperative outcome measures of both groups were compared. The proportion of patients achieving the minimum clinically important difference for the outcome measures was also assessed. Independent t tests were used to compare continuous variables, and Fisher exact test was used to compare categorical variables between the 2 groups. Consistent with the propensity score-matching technique, there were no significant demographic or surgical differences between the 2 study groups at baseline. Oswestry Disability Index, 36-Item Short Form Health Survey Physical Composite Summary, and back and leg pain scores were statistically significantly better at 2 years postoperative than at baseline in both groups. However, at 2 years postoperative, the infection group had a statistically significantly worse back pain score compared with the control group (6.45 vs. 4.70, P = 0.020). Also, a greater proportion of patients in the control group (18, 60%) achieved minimum clinically important difference for Oswestry Disability Index than those in the infection group (8, 27%, P = 0.018). This study demonstrates that patients with acute postoperative deep wound infections after instrumented lumbar spinal fusion have improved outcome measures after surgery but have greater back pain and a decreased probability of achieving minimum clinically important difference.