Objective To observe the differences in dynamic stability and kinematic/kinetic characteristics of the lower limbs between patients with knee osteoarthritis(KOA)and healthy individuals at the begining stage of practicing Tai Chi Yunshou movement.Methods Thirty Tai Chi beginners,including 15 patients with KOA and 15 healthy controls,were recruited to practice Tai Chi Yunshou movement for two hours under the guidance of a Tai Chi expert.A motion capture system and a three-dimensional force platform were used to collect and calculate dynamic stability parameter as well as kinematic and kinetic parameters of the left lower limb during the Yunshou movement.Results Compared with healthy controls,patients with KOA demonstrated a smaller center of mass(COM)-center of pressure(COP)inclination angle,reduced mean and peak ankle dorsiflexion angle,reduced peak hip adduction angle and increased peak knee flexion moment during the Yunshou movement(P<0.05).Conclusions Patients with KOA use adaptive postural strategies to maintain the lateral stability in Tai Chi Yunshou exercise,but a comprehensive training programme should be recommended to reduce the joint loading during flexion of the lower limbs at the benginning stages of this exercise.

Objective To observe the differences in dynamic stability and kinematic/kinetic characteristics of the lower limbs between patients with knee osteoarthritis(KOA)and healthy individuals at the begining stage of practicing Tai Chi Yunshou movement.Methods Thirty Tai Chi beginners,including 15 patients with KOA and 15 healthy controls,were recruited to practice Tai Chi Yunshou movement for two hours under the guidance of a Tai Chi expert.A motion capture system and a three-dimensional force platform were used to collect and calculate dynamic stability parameter as well as kinematic and kinetic parameters of the left lower limb during the Yunshou movement.Results Compared with healthy controls,patients with KOA demonstrated a smaller center of mass(COM)-center of pressure(COP)inclination angle,reduced mean and peak ankle dorsiflexion angle,reduced peak hip adduction angle and increased peak knee flexion moment during the Yunshou movement(P<0.05).Conclusions Patients with KOA use adaptive postural strategies to maintain the lateral stability in Tai Chi Yunshou exercise,but a comprehensive training programme should be recommended to reduce the joint loading during flexion of the lower limbs at the benginning stages of this exercise.