1.363 hospital;2.People'3.'4.s Hospital of Luzhou;5.First People'6.s Hospital of Yibin;7.Affiliated Hospital of Southwest Medical University
Objective:Comparative biomechanical analysis of the self-developed sternoclavicular joint anatomical locking plate,the radial distal oblique T-shaped locking plate and the plate of sternoclavicular hook were carried out,to observe the characteristics and advantages of biomechanics. Methods:Selection of 9 anticorrosive and moist adult cadavers,of these,6 were male and 3 were female.The thoracoclavicular joint specimens were removed completely and the irrelevant soft tissues were removed.The anterior and posterior sternoclavicular ligaments and joint capsules were cut off on both sides,resulting in the complete dislocation model of the sternoclavicular joint.The bilateral sternoclavicular joints of 9 specimen models were randomly numbered and matched and grouped:Group A(Experimental group,sternoclavicular joint anatomical locking plate)、Group B(Control group 1,oblique T-shaped locking plate of distal radius) and Group C(Control group 2,sternoclavicular hook plate),6 sternoclavicular joints in each group.All specimens were placed with steel plates on both sides and fixed on the Universal Ability Test Machine,and three biomechanical experiments were carried out,including loading of distal clavicle,torsion of distal clavicle and anti-pull-out of sternum handle screw.The terminal computer is connected with the universal mechanical tester to derive the data and draw the corresponding stress-deformation curve.The difference was statistically significant (P<0.05). Results:(1)Distal clavicle loading test: The load-displacement of the three groups of specimens showed a linear relationship.When the vertical backward displacement is 20 mm,the average load of the distal clavicle load point of group A,B,and C was（30.31±0.86）N,（27.51±0.72）N,（25.10±1.10）N;there was significant difference among the three groups (P<0.05).The compressive deformation resistance in the experimental group was stronger than that in the two control groups.(2)Distal clavicle torsion test:The relationship between torque and torsion angle is linear.In clockwise torsion experiment,torsional rigidity of A,B,C three groups respectively is 0.288 N.m/°,0.217 N.m/°and 0.180N.m/°,in addition to torsional rigidity of group B and group C was no significant difference (F=2.95,P=0.185),that of group A and group B,that of group A and group C between comparison was statistically significant (P<0.05).In anticlockwise torsion experiment,torsional rigidity of A,B,C three groups respectively is 0.205 N.m/°,0.159 N.m/°and 0.080N.m/°,both two comparison in three sets of the torsional rigidity has statistical significance (P<0.05).The torsional deformation resistance in the experimental group was stronger than that in the two control groups.(3)Anti-pullout test of sternum handle screw:The maximum anti-pullout force of sternum handle screw in group A,B and C was (210.62±17.66)N,（154.89±15.71）N,（184.05±17.50）N;there was a significant difference among the three groups (P<0.05).The anti-pullout performance of the sternum handle screw in the experimental group was better than that in the two control groups.Conclusion:The self-developed sternoclavicular joint anatomical locking plate is superior to the oblique T-shaped locking plate of distal radius and the plate of sternoclavicular hook in terms of anti-compression,anti-torsion and anti-pullout of sternoclavicular screw.It may provide an ideal internal fixation device for the treatment of fracture and dislocation of sternoclavicular joint.