Retrospective study of deep surgical site infections following spinal surgery and the effectiveness of continuous irrigation

Surgical site infection (SSI) is an unfortunate and unpreventable complication of any surgical intervention including spinal surgery. Early deep SSI (EDSSI) after instrumented spinal fusion are particularly difficult to manage due to the implanted, and possibly infected, instrumentation. The purpose of this study is to retrospectively review patients who underwent spinal surgery, investigate the rate of EDSSI, identify patient-related and surgery-related risk factors and to assess the effectiveness of continuous indwelling irrigation on the eradication of these infections. A total of 814 patients (319 women and 495 men) who underwent spinal surgery were enrolled. Mean age at the initial surgery was 57.4 years old. Infections that penetrated the deep fascia within 1 month after the initial operation were considered as EDSSI. The rate of EDSSI, causal organisms, infection management and resolution were studied. Furthermore, we examined the patient-related and the operation-related risk factors. An overall incidence of EDSSI of 1.1% was found. In 177 patients with diabetes mellitus (DM), two patients (1.1%) developed EDSSI. In 28 patients receiving chronic haemodialysis (HD), two patients with infections (7.1%) were identified, which was statistically significantly greater than the other patient populations. Both operative time and intraoperative blood loss were significantly greater in patients with EDSSI than in non-infected patients. Furthermore, the rate of EDSSI in patients undergoing instrumented spinal fusion (3.8%) was significantly higher than that in the other patients. In the nine patients who developed EDSSI, the causal organisms were identified and treated by surgical debridement, antibiotic therapy and continuous indwelling surgical site irrigation. All infections resolved, and no recurrence has been observed at final follow-up. Removal of the instrumentation was required in only one patient. Based on our results, we believe that continuous surgical site irrigation is an effective adjunct in the surgical treatment for early SSI following spinal surgery.