CT-based morphological analysis of spinal fractures in patients with diffuse idiopathic skeletal hyperostosis

Purpose To clarify correlations between spinal fracture and delayed paralysis in patients with diffuse idiopathic skeletal hyperostosis (DISH) using computed tomography (CT) with multiplanar reformatting (CT-MPR). DISH increases susceptibility to unstable spinal fractures, leading to neurological deterioration. The pathomechanism of the neurological injury is unclear. Methods This multicenter retrospective study included 42 DISH patients (32 male; 10 female) treated for 45 spinal fractures during a 5-year period. The mean age at the time of injury was 77.1 ± 10.1 years. The cause of injury, delay in diagnosis, fracture location, and neurological status were recorded, and anterior- and posterior-column fractures, a fracture displacement over 3 mm, and posterior-column ankylosis were assessed using CT-MPR. Results Most fractures (73.8%) resulted from trivial trauma, such as falling from a standing or sitting position. Diagnosis was delayed in 47.6% of the patients, primarily due to delays in seeking medical attention (65.0%). Although 78.6% of the patients were neurologically intact at the time of injury, 54.8% developed paralysis, defined by a change in one or more Frankel-score levels during short-term follow-up. Of the fractures, 39.1% were in the vertebral body, and 60.9% were at the disc level. Fractures with posterior-column ankylosis were significantly associated with delayed paralysis. Conclusions CT-MPR was useful for evaluating spinal fractures and determining treatment in patients with DISH. Fractures associated with posterior-column ankylosis resulted in unstable three-column injuries that led to delayed neurological deterioration. Early surgical stabilization of such fractures is recommended to avoid delayed paralysis.