The Price of Neglect: Delayed Dislocation of a Spinal Fracture in Ankylosing Spondylitis

A 56-year-old male (who had previously been diagnosed to have ankylosing spondylitis [AS]) fell off his chair and presented with severe back pain. X rays showed a characteristic “bamboo spine” but no obvious vertebral collapse or fracture. However, there appeared to be separation of the lower end plate of L2 from the L2 to L3 disc and also discontinuity in the calcified annulus and anterior longitudinal ligament at L2–L3 level [Figure 1a and b]. He was advised to get a computed tomography (CT) scan due to change in the nature of pain and advised that he may need surgery if the diagnosis of a fracture was confirmed. He however opted for conservative treatment with pain killers. He presented 1 month later with paraplegia of 2 days’ duration with complete loss of sphincter control. X-rays showed gross dislocation of L2 on L3 body both in coronal and sagittal planes [Figure 1c and d]. Magnetic resonance imaging showed apparent transection of the thecal sac at this level with fluid in the disc space and retropulsion of L2 on L3 with posterior musculoligamentous disruption as well [Figure 2a-c]. He underwent spinal fixation and decompression, but there was no improvement in his neurological condition.Figure 1: Plain X rays anteroposterior (AP) (a) and lateral (b) views of the lumbar spine 1 day after injury showing on AP view a fused “bamboo spine” with discontinuity in the right lateral aspect (red arrow) and separation of the disc from the lower end plate of L2. The lateral view shows discontinuity of the calcified and fused anterior longitudinal ligament (red arrow) at the same level with no obvious AP translation of the vertebra. X rays of the same region AP (c) and lateral (d) views 1 month after injury showing lateral translation of L2 on L3 (yellow arrows) with break in the fused spinous process line as well. The lateral view shows opening up of the disc space and gross retrolisthesis of L2 on L3 (yellow arrow)Figure 2: Magnetic resonance imaging T2 sagittal (a) and T1 sagittal (b) showing apparent transection of the thecal sac at this level with fluid in the disc space and retropulsion of L2 on L3 with posterior musculo-ligamentous disruption as well. T2 coronal view (c) shows the vertebrae are intact and translocation has occurred through the disc space with fluid in the sameAS is a seronegative arthropathy where the spinal vertebrae fuse with each other due to inflammatory synovitis of the facet joints, calcification of the spinal ligaments and annulus fibrosus of the discs and development of bridging entheses (areas where the soft tissues like ligaments, muscles, and capsules attach to the vertebrae).[1] Over time, the spine becomes rigid and inflexible and vertebrae too become osteoporotic due to stress shielding.[2,3] The fracture line in these patients often extends through all the columns of the spine[1,2] and a CT scan is mandatory to look for the same. The fused spine above and below the site of trauma act as long lever arms at the level of injury and worsen the displacement over time leading to fresh neurological deficits.[1–3] It is important to remember that 15% of patients with AS suffer neurological worsening between the time of injury and presentation to the surgeon[1] often due to some manipulation or unsupervised transfer[3] or even application of a collar. In the setting of trauma to the spine in a patient with AS, even if there is no apparent fracture dislocation on plain skiagrams, further imaging should not be neglected and there is no rationale of offering nonoperative treatment if a fracture of the ankylosed spine is diagnosed[4] in the absence of medical contraindications. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.