Study Of Lower Limb Kinematics And Kinetics In Normal Subjects With Osteoarthritis Of The Knee Based On Qualisys 3D Motion Capture System

Objective:The Qualysis 3D motion capture system was applied to study the changes of kinematic and kinetic in healthy people and patients with osteoarthritis of the knee at different ages,to observe the trend of biomechanical changes of knee motion in gait with age in healthy people,and to provide a theoretical basis for the diagnosis and treatment of osteoarthritis of the knee and its functional recovery.Method:Seventeen patients aged greater than or equal to 60 years with unilateral knee osteoarthritis who attended our osteoarthritis clinic from June 2020 to December2020 were selected as the knee osteoarthritis group.In addition,healthy people without knee pain and other lower limb diseases at different ages were recruited as the control group,and they were divided into three groups according to their age: group A(18～30 years old),group B(31～59 years old),and group C(60 ～75 years old).The dynamic biomechanics of the lower extremities were accurately measured by Qualysis3 D motion capture system.The gait data of the subjects were collected and the trajectory of the joint activity and the force on the joint during the activity were calculated to quantify the biomechanical parameters in gait and indirectly reflect the kinematic and kinetic status of the patients with knee osteoarthritis.The parameters of Cadence,Steride width,Step length,Walking velocity,Stride length,Gait cycle,Double stance phance,Stance phase percentage,Angular velocity peak,Angular velocity average,Angular acceleration peak,Angular acceleration average,Knee flexion angle at initial contact,Knee flexion angle peak,Range of motion,Knee adduction moment first peak,Knee extension moment peak were observed and analyzed in the four groups of subjects during walking.Results:There was a significant difference in Stride length between groups(0.6 ±0.01,0.61 ± 0.05,0.57 ± 0.04,0.53 ± 0.04 m,F = 10.967,P< 0.001).There was a significant difference in Walking velocity between groups(1.15 ± 0.03,1.14 ± 0.05,1.05 ± 0.06,0.72 ± 0.09 m/s,F = 146.945,P < 0.001).There was a significant difference between groups in the Gait cycle(1.05±0.04,1.06±0.03,1.14±0.04,1.37±0.09 s,F=102.489,P<0.001)and between groups in the Double stance phance(0.19±0.02,0.20±0.04,0.24±0.03,0.34± 0.05 s,F=44.056,P<0.001).There was a significant difference in the Knee adduction moment first peak between groups(0.40±0.05,0.41±0.03,0.56±0.06,0.66±0.07 N.m/Kg,F=72.487,P<0.001),a significant difference in the Knee extension moment peak between groups(0.46±0.10,0.46±0.10,0.37± 0.05,0.22±0.05 N.m/Kg,F=30.093,P<0.001),but there was no significant difference between Group A and Group B for both groups of indicators.Conclusion:The biomechanical environment in and around the knee joint changed with age in the healthy population,and the gait parameters were similar in the young and middle-aged healthy population;the cadence,walking velocity,knee adduction moment first peak and knee flexion angle at initial contact in the elderly healthy population changed to different degrees compared with the other two healthy groups.The parameters of step length,walking velocity,knee flexion angle peak,angular velocity peak,and knee adduction moment first peak in patients with osteoarthritis of the knee were changed to a great extent compared to the healthy population.This study observed the trends of knee kinematics and kinetics in gait with age in the healthy population,recorded and analyzed the differences in knee kinematics and kinetics between patients with osteoarthritis of the knee and the healthy population,and provided an important reference for the early diagnosis,treatment modalities and research of osteoarthritis of the knee in patients.