Prevalence, Features, and Predictive Factors of Spontaneous Spinal Arthrodesis in Posttraumatic Thoracolumbar Kyphosis

Abstract

ObjectiveSpontaneous spinal arthrodesis (SSA) is a phenomenon of spontaneous fusion, and SSA is not rare in post-traumatic thoracolumbar kyphosis (PTK). However, few reports have focused on SSA in patients with PTK. The objective of this study was to investigate the prevalence, features and predictive factors of SSA in PTK patients. MethodsIn this retrospective study, 70 patients with PTK were included. Data on the clinical and radiological parameters were obtained and evaluated. According to whether there was SSA or not, patients were divided into SSA group (n=45) or non-SSA group (n=25). A binary logistic regression analysis was used to identify the predictive factors for SSA. ResultsThe incidence of SSA in PTK was 64%. Among 45 PTK cases with SSA, SSA could be present as a solid bridging anterior osteophyte along the vertebral bodies in 11 cases, posterior contiguous bony growth through the facet joints bilaterally in 13 cases, bony formation in both anterior and posterior elements in 18 cases, and direct contiguous bony formation from injured vertebral body to adjacent one in 3 cases. Patients with longer disease duration, larger local Cobb angle and anterior wall height loss ratio (AWHL) of injured vertebral body, and less kyphosis flexibility index were significantly more likely to develop SSA. The parameter of AWHL remained significant in binary logistic regression analysis. ConclusionsSSA in PTK was common, and SSA sign could be present as various patterns, which might have implications for surgical decisions. AWHL was the independent predictor for SSA.