Biomechanics Of Hip Joint In Tai Chi Gait

Objective:Tai Chi(TC)is a traditional exercise in China.Practicing TC has a positive effect on the health of the elderly and some patients with chronic disease.There is no research regarding the effects of TC on the biomechanics of the hip joint.This study is aimed to analyze the hip biomechanics of a typical TC movement,Brush-knee and Twist-step(BKTS).Methods:Twelve experienced elderly males performing BKTS and normal walking in gait laboratory.The scaled-generic musculoskeletal model of each participant was developed in the OpenSim system.A finite element model of the hip joint and pelvis was established and validated.Data from each trail were input to the model for simulation,and the biomechanics were compared between BKTS and walking.Results:Compared with walking,the BKTS movement showed significantly smaller peak vertical joint reaction force of hip,larger range of motion in coronal and horizontal plane,smaller peak muscle force of psoas and smaller peak contact stress.At the first and last peak force of the hip joint,the peak contact stress values of the articular cartilage were 4.95 ± 1.96 MPa and 4.68 ± 1.89 MPa respectively during BKTS,while they were 7.54 ± 2.21 MPa and 8.73 ± 2.32 MPa during walking;the peak von Mises stress of bone around hip were 4.33±0.91 MPa and 3.99±0.95 MPa respectively during BKTS,while they were 5.21±1.06 MPa and 5.68±1.37 MPa during walking.Their distributions two kinds of stress were also different.Conclusions:Compared with walking,TC may better improve the range of motion of hip joint and the coordination of neuromuscular system under safer condition.It is suitable for patients with hip osteoarthritis and elderly people with severe muscle loss,Future clinical studies are needed to confirm the findings of this study in improving the efficacy of symptoms of hip osteoarthritis.