Patients with diffuse idiopathic skeletal hyperostosis (DISH) are at high risk for unstable vertebral fracture, which can be frequently missed. An 80-year-old man with pre-existing muscle lower limb weakness due to frailty was referred from another hospital, presenting with progressive urinary retention and its related symptoms, which had been treated as a urinary tract infection at previous hospital. One week prior to our visit, he had fallen. On arrival, he appeared lethargic and unable to follow commands. He denied any back pain. Computed tomography identified a T10 fracture and dislocation associated with DISH. Although immediate surgical fixation was performed, the patient did not recover from the neurological deficits. Diagnostic delay of DISH-associated vertebral fracture can occur due to both patients' and clinicians' delayed action. We believe this case report can help clinicians recognize this potentially devastating condition.