Diffuse idiopathic skeletal hyperostosis is associated with lumbar spinal stenosis requiring surgery.

Factors related to the onset and progression of lumbar spinal stenosis (LSS) have not yet been identified. Diffuse idiopathic skeletal hyperostosis (DISH) increases mechanical loading on the non-fused lumbar levels and may therefore lead to LSS. This cross-sectional study aimed to identify associations between LSS and DISH. This study included 2363 consecutive patients undergoing surgery for LSS and 787 general inhabitants without symptoms of LSS as participants of the population-based cohort study, Research on Osteoarthritis/Osteoporosis Against Disability. Standing whole-spine radiographs were used to diagnose DISH based on the criteria proposed by Resnick and Niwayama. The prevalence of DISH showed a significant step-wise increase among asymptomatic inhabitants without radiographic LSS, asymptomatic inhabitants with radiographic LSS, and patients with LSS requiring surgery (14.4, 21.1, and 31.7%, respectively; p < 0.001). The distribution of DISH was similar between the groups, but the lower thoracic and upper-middle lumbar spine regions were more frequently involved in patients with LSS requiring surgery. Multivariate analysis indicated that DISH was an independent associated factor for LSS requiring surgery (adjusted odds ratio 1.65; 95% confidence interval 1.32-2.07) after adjustment for age, sex, body mass index, and diabetes mellitus. Among patients with LSS requiring surgery, a higher occurrence of stenosis at the upper lumbar levels and multi-level stenosis were observed in patients with DISH requiring surgery than in patients without DISH. In conclusion, DISH is independently associated with LSS requiring surgery. The decrease in the lower mobile segments by DISH may increase the onset or severity of LSS.