Conservative treatment for stable low-energy thoracolumbar vertebral fractures in nonfused segments among elderly patients with diffuse idiopathic skeletal hyperostosis: A matched case-control study

Diffuse idiopathic skeletal hyperostosis (DISH) is the spontaneous osseous fusion of the spine with anterior bridging osteophytes. It is well-known that conservative treatment for vertebral fractures of fused segment among DISH spines is associated with worse clinical outcomes. However, the prognosis of conservatively treated stable vertebral fractures in neighboring nonfused segments among DISH spines is still unknown. The purpose of this study was to analyze the results of conservative treatment of stable low-energy thoracolumbar (TL) vertebral fracture in nonfused segments among patients with DISH lesions. A total of 390 consecutive patients who visited an emergency department by ambulance with spinal trauma between 2013 and 2017 were retrospectively reviewed. The diagnosis of DISH was determined based on fused spinal segments with bridging osteophytes in at least 3 adjacent vertebrae. For each case of stable TL vertebral fractures in nonfused segments of the DISH spine, we identified 2 age-, sex-, and fracture lesion-matched non-DISH controls who underwent conservative treatment for low-energy TL vertebral fractures during the same period. Of the 33 identified cases of TL fractures with DISH, 14 met our inclusion criteria. The bony union rates of the DISH group and control group were 57% and 75% at the 3-month follow-up examination (P = .38) and 69% and 100% at the 6-month follow-up examination (P = .02), respectively. Among the 13 patients with fractures below the TL junction, fused segments were not diagnosable based on the initial standard radiographs of the lumbar spine for 61.5% of patients. Although this study design was exploratory and the sample size was small, our results suggest that with conservative treatment, stable fractures in nonfused segments in the DISH spine might have a worse prognosis than ordinary osteoporotic vertebral fractures. The diagnosis of coexisting DISH lesions can be missed when only radiographs of the lumbar spine are used to determine the diagnosis.