Purpose: The effect of diffuse idiopathic skeletal hyperostosis (DISH) on spinopelvic alignment in patients with lumbar spinal stenosis (LSS) remains unclear. The aim of this study was to investigate the association between DISH and sagittal spinopelvic alignment in patients undergoing surgery for LSS.
Methods: A total of 132 patients aged >40 years who required surgical procedures for LSS were investigated. DISH was defined by Resnick's and Mata's criteria on preoperative standing whole-spine radiographs. We investigated the prevalence and localization of DISH and its relation to preoperative clinical symptoms. Spinopelvic alignment was measured by the sagittal C7 plumb line, lumbar lordosis, thoracic kyphosis, and pelvic parameters. The association between DISH and spinopelvic alignment was analyzed using covariance adjustment for age, sex, spondylolisthesis, and degenerative lumbar scoliosis.
Results: The prevalence of DISH was 39.4 % and increased with age. Preoperative symptoms showed no differences, regardless of the presence of DISH. Lumbar and thoracic alignment showed kyphotic change in patients with DISH. Patients with DISH with lower fused vertebral ends at the lumbar level (46 % of DISH) still showed significantly decreased lumbar lordosis (p = 0.014) and decreased sacral slope (p = 0.001) after adjusting for age, sex, spondylolisthesis, and degenerative lumbar scoliosis.
Conclusions: The prevalence of DISH in patients with LSS was relatively high. Spinopelvic alignment is affected by the presence of DISH, especially in patients with lower fused vertebral ends at the lumbar lesion. These results may offer an explanation for the frequent kyphotic changes in the spine of elderly patients.