Clinical Factors Associated with Implant Removal Following Surgical Site Infection after Spinal Instrumentation Surgery for Lumbar Degenerative Disease.

INTRODUCTION

Surgical site infection (SSI) is a serious complication of spinal instrumentation surgery that often necessitates implant removal due to biofilm formation. Implant removal adversely affects postoperative outcomes, making implant retention preferable. Although several risk factors for SSI have been reported, those specifically linked to implant removal in lumbar degenerative disease remain insufficiently examined. The purpose of this study was to examine factors associated with implant removal in patients who developed SSI after spinal instrumentation surgery for lumbar degenerative disease.

METHODS

Among 4,743 patients who underwent spinal instrumentation surgery for lumbar degenerative disease between 2013 and 2021 at our institution and affiliated centers, 73 developed SSI. After excluding cases with missing data, 50 patients were retrospectively analyzed. They were categorized into an implant removal group (R group, n=15) and an implant retention group (N group, n=35). Patient characteristics, laboratory findings, surgical factors, and postoperative factors were compared. Univariate and receiver operating characteristic (ROC) analyses were performed to examine factors of implant removal.

RESULTS

The implant removal rate was 30%. Univariate analysis showed associations with the number of previous surgeries at the same level (p=0.004), operative time (p=0.03), interval from surgery to SSI onset (p=0.03), and interval from SSI onset to the first surgical intervention (p=0.03). ROC analysis demonstrated cutoff values of 205 minutes for operative time (area under the curve [AUC]=0.692), 42 days from surgery to SSI onset (AUC=0.702), and 22 days from SSI onset to the first surgical intervention (AUC=0.697).

CONCLUSIONS

Implant removal after SSI in lumbar degenerative disease was associated with a history of surgery at the same level, prolonged operative time, and delayed SSI onset. Early surgical intervention after SSI onset was associated with implant retention.