Risk factors for Implant Failure in Thoracolumbar Fractures Treated with Posterior Long-Segment Instrumentation

Background: Posterior long-segment instrumentation (PLSI) enables the stable repair of thoracolumbar fractures (TLFx) and is thus widely used. However, patients with highly unstable fractures may experience implant failure and related complications (e.g., pain and kyphosis) despite PLSI. Few studies have considered the implant failure rate and risk factors associated with PLSI for TLFx. Methods: This study reviewed 162 consecutive patients with TLFx who underwent PLSI and completed > 1 year of follow-up between April 2011 and December 2019. Implant failure was defined as rod breakage, cap dislodgement, or screw breakage. Risk factors for implant failure were evaluated by multivariate regression analysis that included demographic, injury-related, and surgical factors. Results: There were 15 cases (9.3%) of implant failure at the final follow-up (mean, 28.0 +/- 18.0 months). Current smoker at the time of injury, fracture level, load sharing score, and anterior compression ratio (ACR) significantly differed between the implant failure and control groups (all p < 0.05). Multivariate logistic regression identified current smoker at the time of injury (adjusted odds ratio [aOR], 5.924; 95% CI, 1.405-24.988), mid to low lumbar fracture (aOR, 15.977; 95% CI, 4.064-62.810), and ACR (aOR, 1.061; 95% CI, 1.009-1.115) as predictors of implant failure. Conclusions: This study demonstrated a high implant failure rate in patients with TLFx treated with PLSI. Smoking at the time of injury, mid to low lumbar fracture, and higher ACR were identified as significant risk factors for implant failure. These findings can help guide treatment decisions and improve patient outcomes in TLFx surgery.