Back to the future in traumatic fracture shapes of lumbar spine: An analysis of risk of kyphosis after conservative treatment

INTRODUCTION: Nonosteoporotic burst vertebral fracture could commonly be treated with conservative or surgical approach. Currently, decision-making process is based on thoracolumbar (TL) AO spine severity injury score. However, some factors could affect posttraumatic kyphosis (PTK) and could be taken into account. The aim of the present study is to identify if axial and sagittal fracture shape and initial kyphosis are the risk factors for PTK. MATERIALS AND METHODS: All consecutive patients treated between 2016 and 2017 for TL vertebral fracture with conservative treatment were retrospectively evaluated in the study. Only type A3 and A4 vertebral fractures were included in the study. Patients suffering from osteoporosis or other metabolic bone disease, aged above 60 years old were excluded from the study. Initial and 6 months X-ray from injury were analyze to evaluate local kyphosis and region of injury while initial assessment was performed with computed tomography to better identify fracture type and in some cases magnetic resonance imaging to exclude posterior ligament complex injury. Axial and sagittal view of the vertebral plate was analyzed and classified in three shapes according to fragment comminution and dislocation. Statistical analysis was performed trough STATA13 software. Student's t-test was used to evaluate the differences between initial and follow up kyphosis; odds ratio (OR) was used to evaluate the role of initial kyphosis, vertebral sagittal and axial fracture shape as a risk factor for PTK. Kruskal–Wallis test was used to assess the differences among vertebral shape fractures and final kyphosis. Fisher's exact test was used to assess the differences between fracture patterns and final kyphosis. RESULTS: An initial kyphosis >10° (OR 36.75 P = 0.015), shape c vertebral plate (OR 147 P = 0.0015), and sagittal shape 3 (OR 32.25 P = 0.0025) are strongly related with PTK. Kruskal–Wallis test revealed a statistically significant difference among axial fracture shape (P < 0.0001) and sagittal fracture shape (P = 0.004) and also for initial kyphosis >10° (P < 0.0001). Fisher's exact test showed a significant difference for final kyphosis among pattern c3 and other patterns of fracture (P = 0.0001). CONCLUSIONS: A burst type lumbar vertebral fracture affecting a patient with initial local kyphosis >10° and comminution and displacement of vertebral plate and vertebral body is at high risk to develop a local kyphosis >20° in the follow-up if treated conservatively.