Identification of clinical risk factors and optimal inflammatory marker cutoffs for the diagnosis of septic nonunion at time of presentation.

Abstract

The diagnosis of septic nonunion is difficult due to the risk of occult presentation. The purpose of this study is to identify risk factors for infection prior to nonunion surgery. This retrospective cohort study was completed at a single tertiary referral level one trauma center. Patients were included if they had surgery to repair a nonunion of the femur, tibia, or humerus after operative initial management. Predictors for septic nonunion were determined based on clinical, laboratory, and radiographic findings. 122 Patients met inclusion criteria. 28 Patients (23.0%) were diagnosed with septic nonunion. Clinical risk factors for septic nonunion diagnosis on multivariate regression included nonunion surgery performed at an outside hospital prior to referral (p = 0.003) and early infection requiring debridement within 60 days of initial injury (p = 0.01). Ideal inflammatory marker cutoffs based on ROC curves included WBC > 8.1 × 10⁹/L (p = 0.001) and CRP > 14.1 mg/L (p = 0.001). This study demonstrates additional clinical risk factors and re-defines cutoff values for laboratory biomarkers as predictors for diagnosis of septic nonunion. These data may help providers better identify cases of septic nonunion prior to nonunion surgery.