| Objective: To test the pressure in nucleus pulposus, pressure in facet joints and discheight, through the simulation to two kinds of spinal manipulation that exposed differenttorsion on isolated pig lumbar, to show the mechanism of treating the lumbar vertebraldegeneration based on the biomechanics, to provide the base theory of spinalmanipulation and to improve the clinical effects.Methods: Six fresh lumbar spine specimens from adult pigs were selected. After excesssoft tissues were removed, the specimens were embedded and fixed on the biomechanicalmaterial testing system. Six loading programs were formulated by the usage of materialtesting system to stimulate oblique-pulling manipulation (no longitudinal traction andtorques were0,1,2N.m respectively) and traction-rotation manipulation (longitudinaltraction=250N, torques were0,1,2N.m respectively). With the roles of the programsplayed on each specimen randomly, the biomechanical changes of porcine lumbar spinespecimens caused by passive vertebral rotation were evaluated. It was achieved bymeasurement of changes of pressure in specimens’ nucleus pulposus (L3/4) and in facetjoints and disc height before and after the six programs. Additionally, multi-wayclassification (ANOVA) was adopted to compare the changes of pressure in nucleuspulposus and in facet joints and disc height before and after different programs (LSDmethod was adopted to pairwise comparisons). ρ<0.05represents that the difference wasof significance.Results:1．Pressure in nucleus pulposus (1) Changes of instantaneous value of pressure in nucleus pulposus before and afterloading: pressure elevated after oblique-pulling manipulation showed no statisticalsignificance; pressure reduced after traction-rotation manipulation showed statisticalsignificance (ρ=0.005); the difference existed between traction-rotation group0N.m(torque:0N.m, longitudinal traction:250N) and oblique-pulling group showed statisticalsignificance. However, in traction-rotation group, the differences between group0N.mand group1N.m was statistically significant; on the contrary, there was no statisticaldifference between group0N.m and group2N.m, group1N.m and group2N.m(torquesshowed no statistical significance to the instantaneous values of change of pressure innucleus pulposus).(2) Changes of pressure in nucleus pulposus with time: after oblique-pullingmanipulation, pressure would reduce to a relatively steady state, then elevated to theother one until oblique-pulling was completed. However, traction-rotation manipulationwould give rise to the reduction of pressure to zero state (or even negative), thengradually rose after the stable state. The difference was pressure would overtop the onebefore traction-rotation, and decreased to a relatively steady state, in which pressure waslower than before. Regardless of oblique-pulling or traction-rotation manipulation, eachspecimen reached steady state at different time, and under different loading conditions, itwas different, too.2. Changes of disc height before and after loading: compared with before, thechanges of disc height in oblique-pulling group showed no statistical differences;however, disc height of traction-rotation group was higher than that of before, whichindicated statistical significance(ρ=0.001). The differences between oblique-pulling andtraction-rotation group showed statistical significance (ρ=0.001); no significantdifference existed in oblique-pulling group (torques:0,1,2N.m), by contrast, intraction-rotation group, group0N.m had statistical differences with group1N.m andgroup2N.m, but no statistical difference existed between group1N.m and group2N.m. 3. Results of pressure sensitive film: infrared scanning showed that pressure in facetjoints could be elevated in both traction-rotation and oblique-pulling group, ρ<0.05indicated statistical significance. The larger torque, the higher pressure in facet joints. Nostatistical difference existed between traction-rotation and oblique-pulling group.Conclusions:1. Pressure in nucleus pulposus could be elevated by oblique-pulling manipulationand reduced by traction-rotation manipulation. Under traction-rotation manipulationwithout torques, the reduction of pressure in nucleus pulposus was swiftest and mostsignificant; pressure could be postponed with the existence of torques.2. Under oblique-pulling manipulation, the impact on disc height was not significant,however, disc height could be increased by traction-rotation manipulation. Undertraction-rotation manipulation, the increase of torques had an effect on disc height.However, the increase was the most obvious without torques.3. Regardless of traction-rotation or oblique-pulling manipulation, the increase oftorques could elevate pressure in facet joints. And the larger torques, the more significantincrease of pressure. |
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