Factors associated with rod fracture following surgery for adult spinal deformity: a single-center retrospective study.

Purpose: Adult spinal deformity (ASD) has a significant impact on trunk balance and quality of life in the elderly. Postoperative rod fractures pose significant challenges, but the mechanisms of their occurrence are underexplored compared to other complications such as proximal junctional kyphosis. This study investigated factors associated with rod fracture in patients with ASD.

Methods: A retrospective single-center study analyzed 110 adult patients who underwent spinal deformity correction between 2012 and 2020. Comparative analysis and univariate and multivariate Cox regression analyses were employed to identify factors associated with rod fracture.

Results: In this study, rod fracture occurred in 14.5% of patients. The rod fracture group exhibited a larger change in lumbar lordosis (LL), a higher proportion of patients with pre-operatively existing (pre-existing) vertebral fractures, and a greater percentage of patients with a rod diameter of 6 mm or less compared to the non-rod fracture group. Univariate Cox regression analysis revealed that rod fracture was associated with pre-existing vertebral fracture, LL change, preoperative sagittal vertical axis, and preoperative pelvic tilt. Multivariate Cox regression analysis identified pre-existing vertebral fractures and the amount of LL change as independent factors associated with rod fractures.

Conclusion: Pre-existing vertebral fractures and the magnitude of lumbar lordosis correction are independent risk factors for rod fracture following ASD surgery. Surgeons should consider these factors during preoperative planning to reduce the risk of postoperative rod fracture.

Level of evidence: IV.