Effects Of Different Types Of Ankle Bracing On Biomechanical Characteristics During Landing In Individuals With Functional Ankle Instability

Objective:The purpose of this study was to investigate the effects of lace-up brace and semi-rigid brace on biomechanical characteristics during single leg landing in subjects with functional ankle instability,to discuss the protective effects of different types braces on ankle joint and the lower limb,to provide the theoretical basis for the prevention of ankle sprain and the basic experimental data for the improvement of the design of the protective device,and theoretical reference for the selection of the ankle joint.Methods: Twelve male subjects with unilateral functional ankle instability(FAI)were selected as the experimental group,according to the age,morphological indexes and training programs matching twelve male subjects without ankle injures(control group).The kinematics and kinetics indexes of the single-leg landing were respectively tested by VICON with infrared motion capture system and KISTLER force platform under 3 different ankle braces conditions(no brace,lace-up brace,and semi-rigid brace).The height of the single-leg landing was 40 cm.These differences in kinematics and kinetics were compared with repeated measurements analysis of variance in different ankle braces and different group.Results:(1)The difference in IC PF?Max PF?DF ROM?IV ROM?Max IVV?Max DFV were statistically significant between different ankle braces(P ? 0.01).Compared with wearing no brace,wearing lace-up brace and semi-rigid brace significantly reduced IC PF?Max PF?DF ROM?IV ROM?Max IVV?Max DFV(P?0.01)of FAI during single-leg landing,but there were no difference between wearing lace-up brace and semi-rigid brace(P>0.05).(2)The difference in IC KF?Max KF?KF ROM were statistically significant between different ankle braces(P?0.01).Therewas no statistically significant difference in the kinematic characteristics of the hip between different ankle braces(P>0.05).Compared with wearing no brace,wearing lace-up brace and semi-rigid brace significantly increased IC KF of FAI during single-leg landing,and there were no difference between wearing lace-up brace and semi-rigid brace(P>0.05).Compared with wearing no brace and lace-up brace,wearing semi-rigid brace significantly increased Max KF(P<0.05)of FAI during single-leg landing.And wearing lace-up brace significantly reduced KF ROM when compared to wearing semi-rigid brace(P<0.05)of FAI during single-leg landing.(3)The difference in PVGRF?TTP?LR?Stiffness were statistically significant between different ankle braces(P<0.01).Compared with wearing no brace,wearing lace-up brace and semi-rigid brace significantly increased PVGRF ? LR ? Stiffness,and reduced TTP(P<0.01)of FAI during single-leg landing,but there were no difference between wearing lace-up brace and semi-rigid brace(P>0.05).(4)The difference in DF ROM?KF ROM and HF ROM were statistically significant between different groups(P ?0.05).FAI showed smaller DF ROM ? KF ROM and HF ROM when compared to control group(P ? 0.05).There were no significant differences in other kinematic indexes between the two groups(P> 0.05).And the kinetic indexes between the two groups also had no significant difference(P> 0.05).(5)The interaction of the different ankle braces and different group for all the kinematic and kinetic indexes had no statistical significance(P> 0.05).Conclusions:(1)Wearing lace-up brace and semi-rigid brace significantly limit the ankle movement in the frontal plane of FAI.As to FAI,two kinds of braces could prevent ankle from sprain,but there was no difference in the effect of the two kinds of braces on the prevention of injury.(2)Wearing lace-up brace and semi-rigid brace significantly reduced the IC PF?Max PF?DF ROM?Max DFV of of FAI during single-leg landing,indicating that both of them had restricted the sagittal motion of the ankle joint of FAI.(3)Wearing lace-up brace significantly reduced KF ROM compared to semi-rigid brace of FAI,which was not conducive to the absorption of the ground reaction force on the lower limb.We recommended semi-rigid brace when you chose ankle brace.(4)Wearing lace-up brace and semi-rigid brace did not affect hip jointkinematic characteristics of FAI.(5)Wearing lace-up brace and semi-rigid brace significantly increased peak vertical ground reaction force,loading rate and lower limb stiffness,and reduced the time to peak vertical ground reaction force of FAI during single leg drop,which may increase the risk of limb injury of FAI.(6)The effects of wearing two kinds of ankle braces on health subjects were consistent with FAI.Wearing lace-up brace and semi-rigid brace could also prevent health subjects from ankle sprain,but this can also increase the risk of lower limb injury.(7)Compared to normal subjects,individuals with unilateral FAI showed smaller DF ROM?KF ROM and HF ROM,which might be an important reason why individuals with unilateral FAI had recurrent ankle sprain.