Abstract:

BACKGROUND: Currently in the process of fracture fixation, studies on different plate lengths under a certain number and distribution of screws are few. When plate is too short, fixed plate is not strong, so which usually cause the failure of internal fixation.
OBJECTIVE: To detect the stress changes of different plant lengths under the same number and distribution of screws by three point bending test.
METHODS: Thirty tibial specimens in adult corpses were divided into six groups (five in each group) at random, each of which was cut transversely in the median for constructing non-defect fracture model. Every group was fixed symmetrically with four-hole, six-hole, eight-hole, ten-hole, twelve-hole, fourteen-hole limited contact dynamic compression plates (LC-DCP) separately and each plate was attached by four screws (two screws were the nearest to fracture and the others were the farthest from fracture). Groups were labeled as A, B, C, D, E, F groups orderly.
RESULTS AND CONCLUSION: In three-point bending test, the average strain of fracture site in the group A was maximal and in the group D was minimal. There was significant difference in the average strain of fracture site between the group A and the other five groups (P < 0.05). There was significant difference in the average strain of fracture site between the group B and the C, D, E, F groups (P < 0.05). There was significant difference in the average strain of fracture site between the group C and the D, E groups (P < 0.05). There was also significant difference in the average strain of fracture site between the D and F groups (P < 0.05). It is indicated that during three point bending test, the screw length has significant effect on the stiffness of the plate and screw structure under the same screw number and position. The 8-hole plates and those longer than 8 holes have better elastic deformation ability and stability.