Correlations between repositioning of bone fragment in thoracolumbar burst fractures and size of bone fragment, and AO classification

Background: The reposition of bone fragment is important in the treatment for thoracolumbar burst fractures, but it is not clear whether there are correlations between the reposition of bone fragment and the size of bone fragment, and AO classification in the thoracolumbar fractures. Materials and methods: Forty-two patients were divided into two groups according to whether reposition of bone fragments (Reposition group) or not (Non-reposition group). There were 17 patients in the reposition group and 25 patients in the non-reposition group. All the fractures were classified according to the AO classification system. Neurological status was classified according to American Spinal Injury Association (ASIA) grading. The height and width of bone fragments (HBF and WBF) were measured. Then ratio of height of bone fragment occupying height of posterior wall of vertebrae body (RHBF) and ratio of width of bone fragment occupying transverse canal diameter (RWBF) were calculated. Spearman correlation coefficients were used to evaluate relationships between reposition of bone fragments and those parameters, AO classification. Results: There was a significant difference on the HBF (t=-3.518, P=0.001<0.05), WBF (t=-3.312, P=0.002<0.05), RHBF (t=-2.828, P=0.007<0.05) and RWBF (t=-4.164, P=0.000<0.05) between the two groups. There were significant positive correlations between reposition of bone fragments and AO classification (r=0.569, P<0.01), and RWBF (r=0.429, P<0.01), and RHBF (r=0.361, P <0.01), and HBF (r=0.326, P<0.05), and WBF (r=0.305, P<0.05). Conclusion: AO classification, HBF, WBF, RHBF and RWBF are predictive of reposition of bone fragments in thoracolumbar burst fractures and correlated to reposition of bone fragments.