Knee Biomechanics Finite Element Ana Lysis Female Badminton Player With Single-leg Landing In Overhead Stroke

Objective:Badminton is one of the most popular sports in the world.It is easy to cause a series of sports injuries due to the high intensity and intermittency of badminton,and female players were susceptible to injuries during Badminton sport.As one of the most common techniques in badminton,overhead stroke was often shown on the backhand side of athlete on the backcourt.Knee cartilage and meniscus injuries are more common in the overhead stroke movement.During the single-leg landing of the over-stroke movement,the knee is more likely to be damaged,which including the acute injury of knee cartilage and meniscus caused by impact of ground reaction force and the chronic injury to the cartilage and meniscus caused by load of long-term landing movement.The change in the biomechanical environment of the knee joint during the single-head landing of over-stroke is an important factor that leads to knee injury.The purpose of this study was to calculate the stress of knee cartilage and meniscus based on the examined limb kinematics and kinetics during badminton over-stroke single leg landing,which associated with the single-leg landing of female badminton athletes.It would explain the biomechanics of the knee cartilage and meniscus during the impact phase of landing of overhead stroke which is the key to understanding the mechanism of knee cartilage and meniscus injury.In addition,knee finite element knee model calculated the stress of cartilage and meniscus with different load and joint angles affect the stress which is significant for the prevention of cartilage damage of the knee joint,the treatment and rehabilitation of diseases.Methods:A total of 7 healthy state second-class and first-class female badminton athletes of Shanghai university of Sport were recruited.the kinematic data of single-leg landing were recorded with Vicon 3D motion capture system at a sampling rate of 200 Hz.The GRF data of single-leg landing were collected with two Kistler force plates at a sampling rate of 1000 Hz,and the Vicon and Kilster data were synchronized.After data reduction with visual 3D,the data of kinematic and kinetic which was close to mean value was used as the boundary conditions and load of the knee finite element model.Building a knee finite element model,including bone,cartilage,meniscus and ligaments,with a healthy adult female knee MRI data and verifying the validity of the model.Kinematics and kinetics data were selected as the boundary conditions and load input finite element model to calculate knee biomechanics.knee cartilage and meniscus.The different load and joint angles of model was set to calculate the stress of knee joint cartilage and meniscus to understand the different biomechanics of cartilage and meniscus.Results:1.Kinematics results of the knee of female athletes during the impact phase of the overhead stroke:the flexion angle was-46.8 ± 16.3 °the valgus angle was 5.0 ±6.3 ° and the external rotation angle was-6.7 ± 7.3°.The vertical ground reaction force(vGRF)was 1.7 ± 0.8 body weight;peak vGRF was 3.7±0.6 body weight,posterior GRF was-0.7±0.6 body weight,peak posterior GRF was 3.7±0.6 body weight,posterior GRF was 1.9±0.4 body weight.2.The peak stress and stress distribution of femoral cartilage,meniscus and tibial cartilage at the six characteristic moments of the impact phase of single-leg landing.are as follows:the first peak ground reaction force(F1):1.134MPa,medial;17.71 MPa,posterior-medial;2.159 MPa,lateral;second peak ground reaction force(F2):3.686 MPa,lateral;12.82 MPa,posterior-medial;8.488 MPa,lateral;maximum abduction angle(F3):2.818 MPa,lateral;9.271 MPa,posterior-lateral;5.113 MPa,lateral;maximum adduction angle(F4):1.417 MPa,medial;11.20 MPa,anterior-medial;4.408 MPa,medial;maximum external rotation angle(F5):2.906 MPa,lateral;27.20 MPa,posterior-medial;4.424 MPa;maximum internal rotation angle(F6):3.427 MPa,lateral;6.644 MPa,anterior-lateral;4.362 MPa,lateral,separately.3.Based on the kinematics and kinetics results,the knee finite element was used to calculate the peak cartilage and meniscus stress under different loads and different knee joint angles.Lower load and smaller joint angles had smaller Von Mises stress of cartilage and meniscus.Conclusion:1.During the single-leg landing of overhead stroke,the athletes'knee flexion angle increased continuously,with valgus and external rotation of knee,the angles of valgus and external were easy to approach the joint limit angles.In addition,the higher vertical and posterior ground reaction force impact may further increase the stress of knee.2.During the single-leg landing of overhead stroke,the stress value on the meniscus was significantly higher than that on the femur cartilage and tibia cartilage which means that the meniscus transmits more load.Moreover,peak stress was found on the posterior horn of the meniscus at multiple characteristic moments,which easily increases the risk of injury of the posterior angle of the meniscus and the ligaments and cartilage connected to the posterior angle.3.Knee finite element results showed that increase of knee flexion angle and decrease of knee valgus and rotation angle would reduce the cartilage and meniscus stress.It is recommended that athletes reduce the cartilage and meniscus stress by increasing the knee flexion angle or decreasing the valgus or rotation angle during single-leg landing.At the same time,relevant shoes equipment with better cushioning effects based on the athlete' landing kinetics should be designed,which could athletes to reduce the impact during the landing process.