Student University of South Florida Morsani College of Medicine Tampa, FL, US
Disclosure(s):
Molly Monsour, BS: No financial relationships to disclose
Introduction: Adult spinal deformity (ASD) surgery poses significant risks influenced by demographic factors, spinopelvic parameters, bone quality, and increasingly, muscle integrity. Recent studies have highlighted central sarcopenia, measured by the psoas muscle cross-sectional area (CSA), as a potential predictor of proximal junctional kyphosis (PJK). However, the role of muscle quality in hardware failure (HF) remains underexplored.
Methods: We conducted a retrospective review of ASD surgeries at our tertiary care center from 2016 to 2023. Using axial MRI images and ImageJ software, we calculated the psoas:L4 vertebral index (PL4VI) to assess central sarcopenia. Additionally, measurements were taken at the psoas:upper instrumented vertebral index (PUIVI) at levels L1-L3. HF events, including pseudoarthrosis, rod fracture, rod pullout, and screw complications, were recorded. Statistical analyses were performed using SPSS
Results: Data was collected for 265 patients (mean age 64.2 years, 56% male), with 99 patients (37%) developing HF. 11 patients (4%) had screw pullout, 9 (3%) had screw fracture, 35 (21%) had rod fracture, 3 (1%) had rod pullout, and 74 (28%) had pseudoarthrosis. Screw pullout incidence increased as the CSA of UIV (L1-L3) increased (Pearson rho 0.23, sig. 0.037). Incidence of rod pullout was significantly correlated with L4 CSA (Pearson rho 0.152, sig. 0.035). Furthermore, there was a proportional relationship between L4 right psoas CSA and time until pseudoarthrosis development.
Conclusion : While sarcopenia scores at L4 and the upper instrumented vertebra did not significantly impact overall HF rates, specific aspects of these scores, notably CSA measurements, correlated with components of HF such as rod and screw pullout. These findings suggest that while muscle quality may influence certain aspects of HF, bone quality likely plays a more pivotal role in predicting HF outcomes.