A Research On Finite Element Hybrid Modeling Of Meniscus Injury Of Tennis Players

Objective: In tennis,knee meniscus injury is common and its pathogenesis is complex.According to the different position relationship between human body and tennis,forehand stroke technology has three kinds of standing technology: open,semi-open and closed.The purpose of this study is to explore the relationship between tennis semi-open position batting technique and knee meniscus injury,and to find out the mechanism and regularity of knee meniscus injury.Methods: The data of forehand swing and batting movements of injured and healthy athletes were collected synchronously by VICON three-dimensional infrared motion capture system and dynamometer.The hip and knee joint angles and joint torques were calculated by Visual-3D software.The action data processed by VICON software are imported into Open SIM software in.TRC format.The muscle strength of the related muscles is obtained through scaling model,inverse kinematics,residual calculation and inverse kinematics steps.The CT and MR images of injured athletes’ knee joints were taken,and the two-dimensional sectional images were restored to three-dimensional volume model by MIMICS software.STL was imported into Hypermesh,a finite element pre-processing software,for meshing and material assignment.Open SIM and finite element model were coupled to define the motion of knee joints in semi-open tennis forehand position.The Ls-dyna non-linear calculation was used to calculate the motion of knee joints in semi-open tennis forehand position.The stress distribution of the meniscus is calculated by the calculator,and the results are displayed by Hyperview.Result:(1)The action of Subject A on the horizontal plane is first internal rotation and then external rotation,then internal rotation and finally external rotation.Subject B shows an internal rotation attitude when stepping on the dynamometer,and then external rotation generates force,and only one external rotation is performed.Subject A and B had the same trend of change on the horizontal plane,but the rotation angle of Subject A was larger than that of Subject B,and the rotation time was longer than that of Subject B.In addition,compared with the horizontal moments of the hip and knee joints of Subject A,the direction of the moments was completely opposite,which resulted in relative torsion of the tibia and femur,and torsion and compression loads on the meniscus.The horizontal moments of subjects B hip joint and knee joint were in the same direction.(2)Comparing the muscle strength data of subjects A and B,it was found that there were two peaks in the muscle strength of two muscles of subjects A which produced knee external rotation,and only one peak appeared in the muscle of subjects B which controlled external rotation.(3)The occurrence time of stress concentration on meniscus surface coincides with the occurrence time of ground reaction force,hip joint external rotation moment,knee joint external rotation angle and knee joint internal rotation moment peak.CONCLUSION: Reverse moment of femur and tibia under flexion is the main cause of high stress(injury)of meniscus of knee joint.The knee joint is not fixed in the process of turning the hip.Repeated torsion occurs in the swing and batting process,resulting in relative torsion of tibia and femur,torsion and compression loads on the meniscus.This composite load leads to the increase of meniscus stress and the phenomenon of stress concentration,which increases the risk of meniscus injury.In training,the stability of knee joint can be strengthened,and the twist of knee joint can be controlled consciously to reduce the risk of injury.