Abstract
BACKGROUND: Ossification of the posterior longitudinal ligament (OPLL) is relatively common in East Asian populations, with a recently revealed link to obesity. However, evidence linking OPLL with visceral fat obesity, which is prevalent in the Asian population, is insufficient. We aimed to examine the association between visceral fat obesity and the development of OPLL. METHODS: In a single-center case-control study, data were collected from 120 Japanese patients diagnosed with OPLL and 91 controls without spinal ligament ossification identified during health screenings. From 2020 to 2023, all participants underwent computed tomography to assess visceral fat content and spinal ligament ossification. OPLL was classified as localized (cervical spine) or diffuse (thoracic/lumbar spine). Multivariable logistic regression was conducted to assess the effect size (odds ratio [OR]) of body mass index on the incidence of OPLL and to compare outcomes between groups with a high and low visceral/subcutaneous fat area (V/S) ratio. RESULTS: The proportion of patients with visceral fat obesity was significantly higher in both the localized and diffuse OPLL groups than in the controls (58.9% vs. 64.1% vs. 25.2%, p < 0.05). Patients with OPLL had a higher rate of comorbid visceral fat obesity than the propensity score-matched controls did (56.8% vs. 18.1%, p < 0.001). The effect of BMI on the development of diffuse OPLL was 2.6-fold greater in the high V/S ratio group (OR, 9.50; 95% confidence interval [CI], 2.11 to 42.71) than in the low V/S ratio group (OR, 3.56; 95% CI, 1.51-8.37). CONCLUSIONS: Visceral fat obesity was associated with the development of OPLL, particularly diffuse OPLL. The modifying effect of visceral fat accumulation with overweight status was more strongly associated with diffuse OPLL than was that of subcutaneous fat combined with an overweight status. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.