Impact of Rod Material and Spinopelvic Parameters on Distal Junctional Failure Following Lumbar Fusion: A Comparative Study of Semirigid PEEK and Rigid Titanium Alloy Rods.

Abstract

Aim: To investigate the incidence of distal junctional failure (DJF) in patients undergoing posterior lumbar fusion with either semirigid polyether ether ketone (PEEK) or rigid titanium alloy rods, focusing on the impact of preoperative and postoperative spinopelvic parameters on DJF development.

Material and methods: A retrospective analysis was conducted on patients who underwent short-segment posterior transpedicular stabilization with semirigid PEEK or rigid titanium ally rods between 2015 and 2021. Preoperative and postoperative pelvic parameters, including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), PI-LL mismatch, and lower instrumented vertebra (LIV) were evaluated.

Results: The total cohort consisted of 61 patients with a mean age of 55.85 ± 11.97 years. DJF occurred in 18.03% of patients in the PEEK group (6.67%) compared to the rigid rod group (29.03%) (p < 0.05). Postoperative PI-LL mismatch was a critical factor in DJF development (p < 0.05). Among patients with a preoperative PI-LL mismatch greater than 10°, non-DJF patients achieved a correction of -55.50°. Postoperative reductions in LL were also associated with an increased risk of DJF (p < 0.05). In the PEEK group, DJF patients experienced -19.35° reduction in LL, whereas -11.02° in the rigid rod group.

Conclusion: PEEK rods were associated with a lower incidence of DJF compared to rigid titanium rods. Postoperative PI-LL mismatch and changes in lumbar lordosis and PI-LL mismatch are key predictors to prevent DJF.