Correlation between Posterior Ligamentous Complex and Neurological Injury and Bony Imaging Pa-rameters of Thoracolumbar Injury

Abstract：Objective To analyze the correlation of posterior ligamentous complex(PLC)and neurological injury with bony imaging parameters( vertebral compression,translation,spinal canal invasion,and kyphosis,etc)in thoracolumbar injury. Methods Retrospective analysis of consecutive 48 patients with thoracolumbar injury(T11 ~ L2 )between January-December in 2012 was performed. The osteoporotic compression fractures and pathologic fracture patients were excluded. All patients should have the tests of X-ray,CT scan and sagittal reconstruction,MRI scan. Local kyphosis,injured vertebral wedge angle, anterior and posterior injured vertebral heights,interspinous distance,vertebral translation,anteroposterior diameters of spinal canal were measured on midsagittal CT scan. The injured vertebral compression ratio was calculated. The distance of posterior wall fracture block broke into spinal canal were measured on axial CT scan and ratio of spinal canal invasion was calculated by dividing the spinal canal anteroposterior diameter. The status of the PLC based on MRI signals were recorded as intact,incom-plete injury,or disrupted. Their ASIA motor scores and ASIA Impaired Scale were recorded. Spearman correlation coefficients were analyzed to assess the correlation between bony imaging parameters,PLC injury,and neurological injury. Results There were 3 patients with local kyphosis ﹥ 30°,4 patients with injured vertebral wedge angle ﹥ 30°,6 patients with local kyphosis ﹥20°,11 patients with with injured vertebral wedge angle ﹥ 20°,10 patients with vertebral compression rate ﹥ 50% ,29 patients vertebral translation ﹥ 3. 5 mm,6 patients with interspinous distance increases ﹥ 7 mm,12 patients with spinal canal invasion ratio ﹥ 50% . According to MRI evaluation,17 patients had PLC injury. There were significant positive correlation between lo-cal kyphosis ﹥ 30°,vertebral translation ﹥ 3. 5 mm,interspinous distance increases ﹥ 7 mm and PLC injury. Significant negative correlations were found between vertetral translation ﹥ 2. 5 mm,spinal canal invasion ratio ﹥ 50% ,and neurological injury (AISA impaired Scale and ASIA motor score). There were no significant correlations between PLC injury or neurological injury and other bony imaging parameters. Conclusion Some thresholds for bony imaging parameters were not predictive of PLC and neurological injury. When vertebral translation ﹥ 3. 5 mm,local kyphosis ﹥ 30°,interspinous distantce increases ﹥ 7 mm,thora-columbar injury usually combine with PLC injury . Patient with spinal canal invasion ratio ﹥ 5 0 % and vertebral translation ﹥2. 5 mm tend to merge neurological injury. PLC and neurological structure status should be evaluated by MRI.