Purpose: Ankylosing spondylitis and Forestier hyperosteosis produces a fused vertebral column. The fused vertebrae can be considered like a “spine-bone” which has particular features different from those of the mobile spine. The purpose of this retrospective analysis was to investigate the clinical and radiological particularities of the spine-bone in order to reduce the delay to diagnosis.
Material and results: Forty-eight spinebone fractures were observed over a 17-year period by one practitioner. Twenty of the patients (mean age 62 years) had ankylosing spondylitis and 28 (mean age 81 years) had hyperosteosis. All of the patients were men. Twenty-five were victims of falls, eleven victims of traffic accidents, and six victims of sports accidents (all with ankylosing spondylitis). No notion of trauma could be identified for six patients. Sixteen fractures were diagnosed within 1 to 28 days. Forty-four patients had cord injury including 16 cases which developed secondarily. Four types of fracture were identified:
- type I = anterior opening fracture: 30 patients,
- type II = “sawbone” fracture: 4 patients,
- type III = “rasp line” fracture: 8 patients,
- type IV = fractures comparable to other fractures of the vertebral column: 6 patients.
Fractures diagnosed late were four anterior opening fractures, eight “rasp line” fractures, and four “sawbone” fractures. A CT scan was obtained in all cases and an MRI in 30. Three compressive spinal extradural haematomas were diagnosed. Thirty-two patients died, 31 patients with spinal injuries due to decubitus-related complications and one by rupture of an aneurysm of the aorta.
Discussion: This series illustrates several points. Fracture without trauma is frequent. Diagnosis is made late. Fractures gone undiagnosed lead to neurological complications or nonunion. Diagnosis of “rasp line” fractures cannot be made on standard x-rays, leading us to order a scanner and/or an MRI in all patients with a painful ankylosed spine even if the standard x-ray does not show any fracture. Neurological and extradural haematoma are serious complications. Mortality is high in these debilitated patients. Knowledge of these exceptional fractures of the vertebral column is necessary to improve diagnosis and prognosis.
