Objectives The degree of spinal canal compromise in lumbar disc herniation (LDH) influences treatment decisions and outcomes. Although magnetic resonance imaging (MRI) is the gold standard for assessing LDH severity, limited access in primary and secondary care settings maÿ delay diagnosis and referral. This study aimed to examine whether radiological parameters measured on standing spine radiographs are associated with MRI-defined LDH severity and could support timely referral for advanced imaging. Methods This retrospective cross-sectional study included patients diagnosed with LDH who underwent both standing whole-spine radiographs and lumbar MRI between June 2014 and January 2024. Radiographic parameters assessed were disc height index (DHI), pedicle width-to-sagittal vertebral body width ratio (PW:SBW), pelvic incidence (PI), lumbar lordosis (LL), and sagittal vertical axis (SVA). Canal compromise was quantified on MRI and classified as mild (50%) or severe (≥50%). Binary logistic regression and receiver operating characteristic (ROC) curve analyses were used to evaluate association between radiographic parameters and severe canal compromise. Results An SVA ≥50 mm was independently associated with severe canal compromise (odds ratio = 3.376; 95% confidence interval: 1.658–6.877). The optimal SVA cutoff was 52 mm, yielding a sensitivity of 41% and specificity of 83%. Other radiographic parameters, including DHI, PW:SBW, PI, and LL, were not significantly associated with LDH severity. Conclusions Sagittal vertical axis measured on standing radiograph is associated with the severity of spinal canal compromise in LDH but demonstrates limited discriminatory performance. SVA should not be used as a screening or exclusion tool; however, it may provide adjunctive information to support clinical assessment and MRI referral decisions in selected patients, particularly in resource-limited healthcare settings. Prospective studies are required to validate its role within clinical care pathways.
Surapuchong et al. (Mon,) studied this question.