Visceral fat obesity predicts ossification of the posterior longitudinal ligament: annual health examination data-based evidence.

Abstract

Background context: Recent studies have demonstrated a close association between the development of ossification of the posterior longitudinal ligament (OPLL) and obesity. However, the association between OPLL and visceral fat obesity, which is prevalent in the Asian population, remains unexplored.

Purpose: To examine the impact of visceral fat obesity on the development of asymptomatic OPLL.

Study design: Single-institution cross-sectional study.

Patient sample: Between 2020 and 2021, data were collected from 249 Japanese individuals (147 men and 102 women) who underwent computed tomography (CT) to assess both the visceral fat content and OPLL.

Outcome measures: We assessed patient background information, serum data, and CT images, including the abdominal circumference (cm), total fat area (cm²), visceral fat area (cm²), and subcutaneous fat area (cm²) at the umbilicus level. OPLL localization was assessed using whole-spine CT images.

Methods: The individuals were categorized into 4 groups based on obesity and visceral fat: nonobesity without visceral fat (n=85), obesity without visceral fat (n=18), nonobesity with visceral fat (n=44), and obesity with visceral fat (n=102). OPLL was classified as localized or diffuse when present in the cervical spine alone or in the cervical and thoracic spine, respectively. The prevalence of each type of OPLL was compared between the groups. Multivariable analysis was conducted to calculate the effect size of body mass index (BMI) on the prevalence of OPLL, comparing the high and low visceral fat groups.

Results: The obesity with visceral fat group exhibited a significantly higher proportion of diffuse OPLL than did the nonobesity without visceral fat group (27.5% vs. 7.1%, p<.001). The effect size of BMI for the occurrence of diffuse OPLL was 2.1 times greater in the high visceral fat group (odds ratio [OR], 3.12; 95% confidence interval [CI], 1.66-5.87) than in the low visceral fat group (OR, 1.44; 95% CI, 0.64-3.22).

Conclusions: Our data show that visceral fat, in conjunction with BMI, influences the occurrence of OPLL in the Japanese population. This supports the hypothesis that systemic metabolic disorders share a disease mechanism with OPLL and indicates that the high prevalence of OPLL in Japan may be attributed to physical characteristics that promote visceral fat accumulation.