Biomechanical Characteristics Of The Gait With Functional Ankle Instability

Objectives: Functional ankle instability is the commonest injury in the sports, butstudies on gait of functional instability of the ankle are relatively seldom. This studyfrom gait characteristics of functional ankle instability, angle characteristics, spatial andtemporal characteristics of kinematics of joints and foot exposure characteristics ofPlantar pressure, gravity and other forces. Basic theory and experimental basis wereprovided from the systemetic analysis Biomechanical gait characteristics of the anklewith functional instability was done for ankle injury prevention and rehabilitation.Methods：Study of functional instability of the ankle to the left select subject13(FAI),according to the FAI Group subjects ’ age, height, weight and training projects, andlower limb morphology,15subjects without functional ankle instability were selected ascontrol group. Using Vicon-MX infrared motion-capture system, Kistler forcemeasurement and gait analysis of Zebris treadmill FAI FDM-TDS systems group andcontrol groups for the most comfortable pace of walking test and acquisition phase,stride characteristics, joint angles, time-space, foot-ground contact forces, gravity, footbiomechanical parameters, such as pressure. FAI Group and the control groupcomparison of the ipsilateral lower extremity parameters, using independent samplest-test.Results：①In the Gait characteristics, terminal swing,support phase percentage,swingphase percentage,and the difference in percentage of the standing phase/swing phasebetween the FAI group and the control group was statistically significant.②In thecharacteristics of gait stride, the difference in the left and right step length, stride length,left and right foot the declination, around step width between FAI and control groupswas not statistically significant (P>0.05), but the difference in the left step/leg length,stride length/leg length between the two groups was statistically significant (P <0.05);③As to the joint angle of gait characteristics the difference between FAI andcontrol groups in foot followed the the ground moments angle,maximum flexion angleof support phase, maximum flexion angle of the swing phase at left and right hipenough in X-plane were statistically significant (P <0.05); the difference at left kneein the X-plane swing phase the maximum flexion angle, range of motion between thetwo groups was statistically significant (P <0.05); the difference in left ankle jointsurface in X the ground moments dorsiflexion angle, swing phase.the flexion anglebetween the two groups was statistically significant (P <0.05), the difference in the leftankle joint foot in the Y plane followed the ground moments angle between the twogroups was statistically significant (P <0.05); the difference in the other angle X, Y, Zplane between the two groups was not statistically significant (P>0.05);④Spatial andtemporal parameters between gait FAI group and the control group, only the differenceof thepace between the two groups was statistically significant (P <0.05).⑤Thedifference in the force of the left lower limb peak, peak force/body weight, the forcevalue range/weight in X-direction between the FAI group and the control group wasstatistically significant (P <0.05); the other foot contact force parameters between thetwo groups has no statistic significance(P>0.05);⑥In the characteristics of Gait ofplantar pressure, the difference in the maximum pressure of left and right feet heel,paws maximum pressure, the moment of maximum pressure, the line pressureparameters between the FAI and control groups showed no statistical significance (P>0.05).Conclusions：Gait kinematics and kinetics were different with and without functionalankle instability walking in normal speed;②Gait support with functional ankleinstability significantly increase and decrease either in the swing phase or walking speed;speed of late heel swing phase increased significantly; left step length, stride length andwalking speed were significantly reduced;③Ipsilateral hip, knee and ankle’s flexionand extension of people with functional ankle instability have different degrees ofchange in the sagittal plane,also cause contralateral hip’s flexion and extension have thecompensatory changes; greater varus angle in addition to the ipsilateral ankle foot heelmoment, both sides of the hip and ankle in the coronal plane and the horizontal movement hardly changes;④The plantar contact force in the longitudinal direction ofthe peak force was significantly smaller, which led to an insufficient performance inforward thrust;⑤the foot plantar pressure study were divided into the two parts of theheel and paws,we couldn’t not draw the conclution that whether plantar pressure of thegait with functional ankle instability was different from that of the control group, somore detailed plantar pressure interval division was needed;⑥About the ipsilateralankle foot heel moment, people with functional ankle instability ankle dorsiflexion waslack and had too much varus, the injury risk of ankle varus would be increased duringtheir walking.