Vertebral fracture at the caudal end of a surgical fusion for thoracic vertebral fracture in a patient with diffuse idiopathic skeletal hyperostosis (DISH).

The patient was an 86-year-old woman with back pain after a fall. She had no neurological findings at the initial visit. Plain radiographs and magnetic resonance imaging (MRI) showed diffuse idiopathic skeletal hyperostosis (DISH) and a Th10 fracture. Two weeks later, she started gait exercise with immobilization by a rigid orthosis. Twenty-five days later, she presented with paralysis and numbness of her legs. Computed tomography (CT) showed anterior expansion in the vertebral body of Th10. MRI showed an intramedullary high-intensity area on T2-weighted images at the same level. She was diagnosed as having delayed paraplegia after a Th10 fracture and transferred to our hospital for surgery. Laminectomy of Th10, posterior fusion from Th7 to L1 with pedicle screws and hooks to Th6 and L1 laminae, anterior fusion from Th9 to Th11 with a plate, and autologous bone grafting were performed simultaneously. The patient's paralysis improved, and she started gait exercise with no limitation of bed rest and without an orthosis after surgery. At 8 days after surgery, she again presented with low back pain and paralysis in her legs. CT revealed an L1 fracture, which was the caudal end of the surgical fusion. The decreased kyphosis after surgery compared to that at pre-injury might have caused a subsequent horizontal shear force to L1 when the patient sat on the bed and when she walked. In conclusion, to avoid postoperative adjacent vertebral fracture after fusion, appropriate correction of spinal alignment to that at pre-injury is needed for vertebral fractures in patients with DISH.