Hyperextension-distraction fractures in ankylosing and spondylotic spines: injury profile and treatment results

Study design: Case series study. Purpose: To describe demographic metrics, and clinical and radiographical outcomes of surgical treatment in patients with ankylosed spine (ASP) such as diffuse idiopathic skeletal hyperostosis (DISH) or ankylosing spondylitis (AS) and non-ankylosed spines (NAS) suffering from hyperextension-distraction spine fractures. Methods: Patients diagnosed with hyperextension-distraction fractures between 2012 and 2020 were identified. A retrospective analysis of clinical and surgical data was performed. Similarities between patients with ASP and NAS were evaluated by Fisher’s exact test. Results: Of the 22 patients, 13 had ASP (10 patients with DISH, 3 AS) and nine NAS. Most of these injuries involved the thoracolumbar spine (45.4%). All patients with NAS presented some sign of spondylosis: facet joint degeneration, intervertebral osteochondrosis, and anterolateral osteophytes. None of the patients with NAS and 30.7% with ASP suffered low-energy mechanisms (p =.11). All the patients with NAS and 61% of the patients with ASP had associated injuries (p =.04). On average, the instrumented levels were four (range, 2–6), achieving a fusion rate of 94.7% in all groups. Most of the ASP and NAS presented post-operative complications respectively (p =.65). Conclusion: Hyperextension-distraction spine fractures are not unique in ASP. In patients with spondylosis and high-energy accidents, we should suspect those fractures and rule out associated injuries, fractures in other vertebral segments, and acute spinal cord injury. The four-level instrumentation achieved an effective fusion rate in all patients.