Thoracolumbar Vertebra Fracture The Vertebral Pedicle Fixation Injury Biomechanics Of Comparison

Objective:according to Biomechanics test, compare the difference between Thoracolumbar fractures by injury vertebral fixed and not by the vertebral pedicle fixation injury technology in three different internal fixation method of resistance to pull down screws output and axial stiffness, uproot energy distinction and discuss the safety and effective of Thoracolumbar fractures by injury vertebral fixed. Supporting further more Biomechanics dating and theory basis for the clinical rational selection.Method:Acquisition6nationality relatively fresh moist with thoracic spine(without tumor,degeneration,trauma.And random sampling),then eliminated soft tissue and muscle, carefully keep ligament and joint prominent.Keeping the sample nature-bit,avoiding Hyperextension,flexion and rotation.The sample should be kept by two plastic bags after counting the size.Then dividing them into three groups.Group1:L1fracture, Both T12and L2are fixated on pedicle according2sides.(4nails Group A) Group2:L1fracture.L1T12are fixated on1side.L2is fixated on both.(5nails Group B) Group3:L1fracture.L1L2T12are all fixated on two sides.(6nails Group C)Result:The wound spine which was fixated already will deformation under the power of500N(Human Physiological load).The less the spine deformation,the batter the wound spine is fixated..Group A"s average deformation power is449±43με,Group B is397±38μεand Group C is340±33με.GA is about12%higher than GB,GB is14%higher than GC.GA is24%higher than GC.Statistics show that between the two groups showed significant differences (q=3.74, P＜0.05).GC"s deformation power is smaller than GA and GB,so the way that GC is fixated is mucher better than GA and GB.and GB is better than GA.The longitudinal displacement on wound spine will take place by the human Physiological load.The displacement is a danger to the vertebra.GA"s average displacement is3.43±0.31mm;GB is3.06±0.28mm and GC is2.62±0.24mm.GA is11%higher than GB,GB is14%higher than GC,and GA is24%than GC.Statistics show that between the two groups showed significant differences (q=3.86, P＜0.05),GC"s displacement is much smaller than the other two,it shows that using6snails is much firm.GB"s way is better than GA.The strength of spine is the date that the most power which the spine could endure.The larger the number is,the stronger a spine is.It is an important Mechanical index for pedicle screws.GC and GB"s average strength is6.53±0.62Mpa and5.64±0.52Mpa.The date of GA is4.63±0.42Mpa.GB is18%larger than GA,GC is14%larger than GB,29%than GA.Statistics show that between the two groups showed significant differences (q=3.77, P＜0.05).It shows GC is much better than A and B.Axial stiffness of spine could show under the power of axial pressure,the spine’s ability to avoiding transformation.A large axial stiffness means a steady spine.GA’s axial stiffness is148±12N/mm,GB is165±13N/mm,GC is193±17N/mm.The rate of difference among the three group is11%14%and24%.Statistics show that between the two groups showed significant differences (q=3.82, P＜0.05).The result shows that GC is better than GB,GB is better than GA.GC is the most steady group.The spine’s torsional force is count by Torsional stiffness and Torsional strength.GA’ Torsional strength is1.35±0.12N.M,meanwhile Torsional stiffness is0.53±0.38N.CM/Deg.GB’s max Torsional strength is1.50±0.14N.M,and torsional stiffness is22.80±1.64N.CM/Deg.GC’s torsional strength is1.68±0.16N.M,and torsional stiffness is26.62±1.86N.CM/Deg.Statistics show that between the two groups showed significant differences (q=3.82, P＜0.05).GC is the most powerful group to against the torsional force among the three.In output experiment pulled resistance (PULL-OUT),the three groups have nearly the same performance. group A’s resistance to PULL is480±46N.Group B is474±40N and Group C is487±54N.There is no significant difference.The force cost when pull-out:Group A is7.86±0.68J, Group B is7.64±0.44J, group C is7.88±0.52J.There is no significant difference in statistic too.It shows that:The same people,same nail’s resistance to PULL is almost the same,and the difference is just the individual difference.Result:After the fixation when Vertebral fractures,the spine’s strength,stiffness,stability are all rising.Fixation it or not will have significant difference in Biomechanics.(P＜0.05).Fixation of the wound spine’s twist strength and stiffness are better than No-Fixation.(P＜0.05).The result also show that6snails is better than5-snail and4snails.(P＜0.05)Biomechanics experiment shows:Fixation is better than no-fixation,six snails is better than five-snails and Four-snails.Not only stable and efficient but also make the operation much easier.