Comparison Of Lumbosacral Sagittal Parameters Between Adolescent And Mid-age Patients With Lumbar Disc Herniation

Objective: To evaluate the lumbar lordosis and sacral slope in adolescent lumbar disc herniation patients,then compare them with those of mid-age patients with lumbar disc herniation,and to explore its clinical significance.Methods: Among patients which had been treated in our department from June 2013 to June 2016,47 adolescent lumbar disc herniation(ALDH)patients,with the age ranging from 14 to 25 years(averaged 20.4±3.0 years),were reviewed retrospectively.There are 10 cases with bilateral hamstring muscle tightness among them.While 47 patients with lumbar disc herniation,with the age ranging from 40 to 60 years(averaged 54.1±5.1 years),were selected as the control group.On lumbar lateral X-ray,lumbar lordosis is defined as the angle between the upper end-plate of L1 and the upper end-plate of S1,and sacral slope is defined as the angle between the upper end-plate of S1 and the horizontal line.The angle is accurate to 0.1°.A further statistical analysis as independent t-test was made upon the measured data of two groups.Result: The adolescent group’s average lumbar lordosis was 31.4°±11.3°,and the average sacral slope was 29.6°±7.6°.The average lumbar lordosis of 10 adolescent patients with bilateral hamstring tightness was 30.8°±5.4°,and the average sacral slope was 27.6°±2.0°.The average lumbar lordosis of the other 37 cases of the adolescent group was 31.6°±12.5°,and the average sacral slope was 30.1°±8.4°.The mid-age group’s average lumbar lordosis was 37.9°±7.2°,the average sacral slope was 31.6°±7.5°.The lumbar lordosis of ALDH group was significant lower than that of mid-age group(P < 0.05).The sacral slope of ALDH group was smaller than that of mid-age group(P > 0.05).However,there was no statistical significance between them.Besides,the average sacral slope of 10 adolescent patients with bilateral hamstring tightness was smaller than that of the other 37 cases of adolescent group.A significant coefficient relationship between lumbar lordosis and sacral slope was showed by Pearson correlation coefficient test.Conclusion:1.The lumbar lordosis of ALDH is significant lower than that of mid-age patients,which means lumbar curve is tending to a more linear arrangement,and both the vertical stress load of lumbar intervertebral disc and the shear force load of annulus fibrosus will be increased seriously.2.The average lumbar lordosis and sacral slope of ALDH patients with bilateral hamstring tightness is lower than that of the other cases of ALDH group.The reason is considered as a posterior rotation of the pelvis around the coxofemoral joints by contraction of the hip extensor muscles,especially by the hamstring muscle,and a secondary decreasing of lumbar curvature,which remains to further research.3.Though the sacral slope of ALDH is smaller than mid-age group’s angle,there’s no statistical significance between them.4.Since the tending to a more linear arrangement of lumbar vertebral can induce a quick degeneration progress of intervertebral disc and it may be caused by an abnormal condition of hamstring muscle,the following research should be focused on the lumbosacral sagittal parameters’ changes and the pathological degeneration in lumbar intervertebral disc of ALDH patients with bilateral hamstring tightness.And to investigate the significance of hamstring muscles tightness in the pathogenesis of lumbar disc herniation,which is helpful for the developing of preventive measures for ALDH.