The Influence Of The Number Of Screws On DCP Strain And Stiffness In The In Vitro Fracture Model With Bone Defect

Objective To investigate the effect of the number of screws on the bending stiffness and dynamic compression plate (DCP) strain in the in vitro fracture model with bone defect.Methods Twenty-four wooden sticks of the chestnut were separated into four groups at random,every group included six specimens.To model a fracture with bone defect,every stick was cut transversely and leaving a 5 millimeter gap in the median and a twelve-hole dynamic compression plate was attached by screws.Three rectangular strain gauges were installed on the each plate to evaluate the strains.The axis of each gauge element was mounted longitudinally so as to measure the surface strain of DCP in response to cantilever bending.Screw position of the four groups were: A 1-2-6, B 1-2-3-6, C 1-2-3-4-6, D 1-2-3-4-5-6. In cantilever a bending, the constructs were loaded from the tension side and the compression side., A probability level of P<0.05 was considered significant.Results Among all groups, this investigation revealed no significant difference about the bending stiffness and median plate strains in cantilever bending;The strains in the median region of plate were highest and decreased longitudinally along the plate.Conclusions In a model simulating a fracture with bone defect,this study showed that the symmetrical omission of screws ,with a given plate length and working length ,did not affect significantly the bending stiffness and median plate strain.