Occult vertebral fractures in ankylosing spondylitis

Study Design: A retrospective review of patients with ankylosing spondylitis involved in blunt trauma. Setting: Patients referred to two Level I trauma centers. Objectives: To determine the incidence and clinical sequelae in this patient population where vertebral injury was diagnosed on a delayed basis. Summary of Background Data: The ankylosed spine is at increased risk for fracture and spinal cord injury. Radiological identification of injury is more difficult than in the normal spine. Results: Over a 5 year period, 21 patients were identified with seven having an occult vertebral fracture not recognized as the primary injury or occurring as a second noncontiguous injury level. In these cases, delay in diagnosis of the occult injury was from 3 to 22 days. Development of secondary neurological deficits occurred in three patients. Conclusions: A high index of suspicion and an appreciation of the extreme instability of a fracture in ankylosing spondylitis must be present.