Biomechanical Characteristics Of Landing Motion Of Unilateral Functional Ankle Instability Under Visual Deprivation

Objective: Vision,as an important input of sensory information,plays an important role in maintaining the stability of human posture.However,in the case of visual neglect or absence,the mechanical characteristics of lower limb joints during landing are still unclear,especially in the case of functional instability of ankle joints.Therefore,the aim of this study is to explore the biomechanical characteristics of the falling ankle functional instability group under the condition of visual deprivation by comparing the landing mechanics characteristics of the functional instability group and the control group after visual deprivation,It provides theoretical basis and experimental basis for the prevention and treatment of functional ankle joint injury.Methods: In this study,12 functional ankle instability patients from School of Physical Education of Soochow University were randomly selected as the experimental group,and 12 patients without any ankle injury were matched as the control group.The Vicon 3D motion capture system and Kistler force table were used to conduct a landing experiment with a height of 30cm(without initial vertical velocity).The experiment was divided into two parts: visual deprivation and non-visual deprivation.During visual deprivation,the subjects wore an eye mask to mask their vision.The kinematics and dynamics parameters in the landing process were collected,and the collected data were statistically tested for index differences through two-factor repeated measurement an OVA.The test level was defined as ɑ=0.05.Results:(1)The knee flexion Angle of functional ankle instability group and control group was larger(P<0.05),the hip,knee and ankle flexion amplitude was decreased(P<0.05),and the ankle pronation degree was increased(P<0.05)at the moment of landing in the functional ankle instability group than that in the non-visual deprivation state.The changes of vertical length of lower limbs were smaller(P<0.05),and the stiffness of lower limbs and ankle joints were larger(P<0.05).(2)visual deprivation status whereabouts to the functional ankle instability group and the control group on the vertical ground reaction force peak than no visual deprivation(P<0.05),and the ground reaction force outside the peak time,the direction of the difference has statistical significance(P<0.05),the load rate is higher than without visual deprivation landing(P<0.05),In terms of the torques of each joint,the torques of hip,knee and ankle joints on the sagittal plane and frontal plane all increased to varying degrees(P<0.05).(3)The flexion amplitude of knee joint and ankle joint in the functional ankle instability group was lower than that in the control group during visual deprivation landing(P<0.05),and there were statistically significant differences in the degree of knee and ankle pronation at the moment of touchdown and at the stage of landing(P<0.05).However,the changes of lower limb vertical length in the control group were greater than those in the ankle sprain group,and lower limb stiffness and ankle stiffness were less than those in the ankle sprain group(P<0.05).(4)When visual deprivation landed,the peak time of vertical and right ground reaction force in the control group was later than that in the functional ankle instability group,and the hip extension moment and ankle dorsiflexion moment were also smaller than that in the functional ankle instability group(P<0.05).Conclusions:(1)visual deprivation status whereabouts,due to the visual information input,unable to effectively adjust the musculoskeletal system landing strategy,made within the buckling amplitude reduction,lower limb joints-outer margin,joint torque increase,thereby weakening the ability to buffer the ground reaction force,reduces the stability of the lower limb joints,weakened the motor movement control ability,Increased risk of sports injuries in healthy and functional ankle instability groups.(2)The degree of ankle valus in the functional ankle instability group was greater than that in the healthy group,and the stability of lower limb joint was weaker than that in the healthy group,due to the decreased proprioception ability and muscle strength around ankle joint.Thus,it is easier to increase the chance of injury.