P139. High rate of mortality after spinal trauma in patients with ankylosing spondylitis

BACKGROUND CONTEXT Spinal trauma in patients with Ankylosing Spondylitis (AS) often result in devastating injuries, as minor insult can manifest in spinal instability and spinal cord injury. Initial diagnostics include CT and MRI of the injured spinal region, which may indicate need for surgery. The significance of radiological findings and subsequent need for surgery in this challenging injury is not well described. PURPOSE The purpose of this study was to describe radiological findings in patients with AS sustaining spinal injuries and to analyze rate of neurologic injury, radiologic canal compromise and in-hospital mortality. STUDY DESIGN/SETTING Multicenter retrospective analysis. PATIENT SAMPLE Eighty-one patients with ankylosing spondylitis sustaining spinal trauma. OUTCOME MEASURES Rates of neurologic injury, radiologic canal compromise, in-hospital mortality, cause of death. METHODS Patients with AS (identified in radiology report) sustaining spinal injuries identified by CT or MRI were retrospectively reviewed from two level 1 trauma hospitals. Patients with prior spine surgery were excluded. CT and MRI studies at the time of injury were reviewed for fracture pattern (AO classification), ligamentous disruption, and evidence of canal compromise >50% (fracture displacement, epidural hematoma, disc herniation). Patient records were reviewed for injury mechanism, neurological status (radiculopathy, weakness, or paresthesias), need for surgical fixation, and in-hospital mortality. RESULTS A total of 81 patients with AS sustaining spine trauma were identified (mean age: 69 years, SD: 14.9; 80.2% male). Twenty-nine patients (35.8%) presented with neurological symptoms (ASIA D: 11 patients, C: 4 patients, B: 4 patients, A:5 patients). Seventy patients (86.4%) reported low-energy mechanism of injury (ground level falls). 65 patients (91.5%) sustained no associated injuries. Ankylosis of the entire spine was observed on CT in 77 patients (95.1%). AO Spine Type C injury was most common (52.1%). Fracture involving all three columns were identified on CT in 64 patients (79.0%). Three-column injury was identified on four additional patients on MRI, increasing overall three-column injury diagnosis to 68 patients (84.0%). Fracture displacement on CT causing canal compromise was observed in 40 patients (49.4%). Among patients without fracture displacement on CT causing canal compromise, 10 additional patients were observed to have canal compromise on MRI from hematoma or disc herniation increasing overall canal compromise to 50 patients (61.7%). Among patients who underwent MRI, 89.7% of patients were observed to have anterior longitudinal ligamentous injury and 75.4% were observed to have posteroligamentous complex injury. Fifty-eight patients (71.6%) underwent surgical fixation (51 patients posterior approach, 7 patients combined anterior posterior approach). Overall, in-hospital mortality rate was 8.6% (7 patients), with cause of death attributable to aspiration pneumonia in four cases. CONCLUSIONS In this multi-institutional series of 81 patients with AS sustaining spinal trauma, 7 in 10 patients required surgical fixation and nearly 1 in 10 patients expired in the hospital. Despite the vast majority of injuries being attributed to be low-energy falls, 79.0% of patients sustained three-column injuries, 61.7% of patients were observed to have canal compromise or evidence of cord compression, and 35.8% of patients presented with neurological compromise. Spine surgeons should be aware that severity of injury on CT as well as mortality may be under-estimated in this patient population. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.