THE ASSOCIATION BETWEEN HOUNSFIELD UNIT AND PROXIMAL JUNCTIONAL KYPHOSIS IN ADULT SPINAL DEFORMITY SURGERY: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract

Objective: This study investigated Hounsfield unit (HU) differences in adult spinal deformity (ASD) surgery patients with and without proximal junctional kyphosis (PJK), a common complication. Summary Background Data: Previous studies have identified osteoporosis as a PJK risk factor, and CT scanning is a valuable tool for detecting osteoporosis through HU measurements. The study aimed to determine the level of HU difference between patients diagnosed with and without PJK. Methods: We conducted a meta-analysis using a random-effects model of randomized controlled trials and cohort studies that assessed HUs for ASD surgery patients who developed PJKs. We searched in PubMed, Embase, Ovid, The Cochrane Library, and Web of Science up to October 2022 and had two authors extract data and evaluate bias. Results: Four cohort studies with 250 patients were included in this study. Measurements of HUs at upper instrumented vertebra (UIV) and UIV+1 showed significant differences between PJKs and non-PJKs. (Mean difference (MD) at UIV: −25.36, 95% CI: −39.16, −11.56, p = 0.0003; MD at UIV+1: −21.06, 95% CI: −38.25, −3.88, p = 0.02). Conclusions: The study found measuring HUs of UIV and UIV+1 can predict the occurrence of PJK in ASD surgery. Further prospective studies are warranted to validate our findings.