Comparative Analysis of Hounsfield Units and Vertebral Bone Quality Scores for Predicting Proximal Junctional Failure in Female Adult Spinal Deformity Patients Undergoing Planned 2-Stage Corrective Surgery with Lateral Lumbar Interbody Fusion

Abstract

This study aimed to evaluate the utility of computed tomography (CT)-based Hounsfield units (HUs) and magnetic resonance imaging-based Vertebral Bone Quality (VBQ) scores as alternatives to dual-energy x-ray absorptiometry for predicting the risk of proximal junctional failure (PJF) in female patients with adult spinal deformity (ASD) undergoing 2-stage corrective surgery with lateral lumbar interbody fusion (LLIF). The study included 53 female patients with ASD who underwent 2-stage corrective surgery with LLIF from January 2016 to April 2022 with a minimum follow-up of 1year. CT and magnetic resonance imaging scans were evaluated for their correlation with PJF. Of the 53 patients (mean age 70.2years), 14 had PJF. Patients with PJF had significantly lower HU values at the upper instrumented vertebra (UIV) (113.0±29.4 vs. 141.1±41.5, P=0.036) and L4 (113.4±59.5 vs. 160.0±64.9, P=0.026) than those without PJF. However, there was no difference in VBQ scores between the 2 groups. PJF correlated with HU values at UIV and L4 but not with VBQ scores. Patients with PJF also had significantly different pre- and postoperative thoracic kyphosis, postoperative pelvic tilt, pelvic incidence minus lumbar lordosis, and proximal junctional angle compared to those without PJF. The findings suggest that measuring HU values at UIV or L4 by CT may be useful for predicting the risk of PJF in female ASD patients undergoing 2-stage corrective surgery with LLIF. Therefore, CT-based HUs should be considered in ASD surgery planning to reduce the risk of PJF.