The Three-dimensional Motion Analysis Of Human Natural And After TKA Knee Joint By Motion Capture Measurement Based On MATLAB

This paper,supported by the National Natural Science Foundation of China on the research on high-flexion stability mechanism of high-flexion artificial knee,compared and studied the kinematic characteristics of human knee tibiofemoral joint of healthy people and subjects after TKA during squat,gait and upstairs climbing.The motion capture system and other measurement equipment were adopted in the study.The knee joint movements of healthy people and subjects after TKA during squat,gait and stairs climbing were measured,and the coordinate data of all makers on subjects were obtained.The anatomical feature points in human lower limb and global and local coordinate systems of human body were defined.Referring to the research of other scholars,the human local coordinate systems of femur and tibia were established.A processing method for human joint kinematics data was designed by writing programs on MATLAB software.The coordinate data of Markers measured in this experiment were processed by the method.Then the relative rotation and translation motion of femur with respect to tibia were obtained by the established local coordinate systems of femur and tibia and coordinate transformation.The kinematic characteristics of human knee tibiofemoral joint of healthy people during squatting were compared and analyzed with other relative research results firstly,and the analyzing results prove the reliability and validity of this research.Then the six degrees of freedom data of tibiofemoral joint of healthy people and subjects after TKA during squat,gait and upstairs climbing were compared and analyzed.The results indicate that compared with the knee joint motion of healthy people,the degrees of external rotation of femur with respect to tibia of subjects after TKA increase 4.6 degrees during squat.During gait of subjects after TKA,the degrees of external rotation of femur with respect to tibia increase 9.7 degrees.What's more,the degrees of external rotation of femur with respect to tibia of subjects after TKA increase 14 degrees,and the degrees of posterior translation increase 1.2mm during upstairs climbing.Therefore compared with healthy people,the external rotation and posterior translation of knee tibiofemoral joint of subjects after TKA have the similar variation trend,the degrees of flexion of femur of subjects after TKA in actions are smaller,and the flexion of knee joint of subjects after TKA during squat is less than 80 degrees due to the limited joint.The results of this research enrich the database of knee joint motion,and could be used to provide a reference for the study of prevention of knee injuries,rehabilitation of patients after TKA and the design and optimization of artificial prosthesis.