Design Of Upper Thoracic Anterior Titanium Plate Fixed System And Evaluate Biomechanical Stability Of It In Vitro Study

Objective: Upper thoracic anterior titanium plate fixed systen(upper thoracic anterior titanium plate fixed systen,UTAP) was designed according to the anatomic characteristics of upper thoracic spine of Chinese and evaluated biomechanical stability of it in vitro studyMethods: UTAP was designed according to the anatomy of upper thoracic spine of Chinese.The study composed of the two parts: Design of UTAP was the first parts.Anatomic parameters of the upper thoracics of Chinese were obtained on basis of literature and our previous researches UTAP on the basis of distraction and compression plate fixation,locking technique between screw and plate and unicortical screw fixation.Part two was for biomechanical study of UTAP.Stress distribution of plate was analyzed by setting up the model of three-dimension finite elements. Fifteen fresh intact C7-T6 structure of spine cadaveric speciments randomly were divided into three groups:Group B with UTAP,Group C with prespred cervical anterior locking plate fixation(cervical anterior locking plate fixation,CALP).Group D with imprespred CALP.After the range of motion(range of motion,ROM) of 15 intact speciments were tested ,ROM of models of different fixations were succedently performed.The results were analyzed by statistic at last.Resuths: UTAP answered for the anatomic feature of Chinese upper thoracis. ROM of natural intact speciments of three groups were no significant difference(p>0.05).The stability of flexion was B>D>C>intact speciments(A),Significant difference between B and A was found(p=0.012).there was not significant difference in others. The stability of extension arranged as follows: B>C>A>D,Under the extention between B and A,C,D was significant difference(P=0.001,P=0.021,P=0.01), and with no significant difference in the others.Under the rotion the order of stability was B>C>A>D.Between groups have no significant difference in the rotation.The order of stabilities under the lateral bending was A>B>C>D.There were not significant difference between B and A,with significant diffirence between A and C,D(P=0.005,P=0.002). Between other groups was no significant difference under the lateral bending.Conclusion:1.The analysis of three-dimension finite elements indicated that the stress concentrated on the surround of bone screw. 2.UTAP is simple and easily operated,can suppy immediate stability in anterior fusion and plate fixation in the upper thoracic spine.UTAP has better biomechanical stability than CALP. 3. If CALP was applied to upper thoracic spine,plate should be prespred according to physiological kyphosis of upper thoracic spine.