The Effect Of The Number Of The Screw In The Dynamic Compression Plates On The Stability Of Plate And Screw Structure Torsion

Objective: To investigate the effects of the number of the screw in the dynamic compression plates on the stability of plate and screw structure in vitro.Method: Thirty wooden sticks of the chestnut were divided into five groups randomly. Every stick was cut transversely in the median and a twelve-hole dynamic compression plate was attached by screws. Three sensor gauges were installed on each plate to evaluate strain. Screw position of the five groups were: A1—6;B1—2—6;C1—2—3—6;D1—2 —3—4—6;E1—2—3—4—5—6. Each group was tested by torsion.Result: In all groups, the group A of average plate strain in the fracture is (249.50 ± 63.91) , the group B of average plate strain in the fracture is (236.00 ± 40.05) , the group C of average plate strain in the fracture is (294.00 ± 93.07), the group D of average plate strain in the fracture is (361.67 ± 52.41), the group E of average plate strain in the fracture is (380.50 ± 50.63) . The B group has the least strain at 2.142° in torsion compare with other groups , has no effect of the rigidity of plate and screw structure in torsion.Conclusion: As the same plate length, screw number affects the stability of dynamic compression plate structure in torsion. In torsion , every groups have obvious effect of the stability of plate and screw structures. At 2.142° ,the rigidity of A group is least and the rigidity of E group is most.