The Effect Of Dual Task On Gait Symmetry In Patients 6 To 12 Months After ACL Reconstruction

Objective:The purpose of this study was to evaluate the limb symmetries and the influence of dual task on gait pattern in patients 6 to 12 months after anterior cruciate ligament reconstruction.Methods:Twenty-five male patients respectively completed walking under normal and dual task conditions.Kinematic,kinetic and electromyography data were acquired respectively and simultaneously with eight-camera high-speed video capture system(Vicon,100Hz),force platform(AMTI,1500Hz)and myoelectric apparatus(Noraxon,1500Hz).Results:(1)As compared with nonsurgical limb,the surgical limb showed smaller peak hip adduction angle during mid/terminal stance phase,peak hip abduction moment during loading response and mid/terminal stance phase,peak knee flexion angle during gait cycle,knee flexion-extension range of motion(ROM)and peak knee flexion moment during mid/terminal stance phase as well as larger peak hip abduction angle and hip extension angle during preswing phase(p<0.05).The peak amplitude of the electromyogram(EMG)signal and integrated EMG of hamstring on the operated side were larger than on the non-operated side(p<0.05).(2)Patients showed smaller peak hip extension angle during preswing phase,peak hip flexion angle during swing phase,peak knee flexion angle during gait cycle,peak ankle dorsiflexion angle and ankle dorsi-plantar flexion ROM during mid-stance phase under dual task condition compared with normal walk condition(p<0.05).Under dual task condition the peak hip flexion moment during stance phase,peak knee extension moment during loading response and mid/terminal stance phase and peak ankle dorsiflexion moment were smaller compared with normal walk condition(p<0.05).The nonsurgical limb had the same integrated EMG of hamstring under both dual task condition and normal walk condition(p>0.05),but the surgical limb showed smaller integrated EMG of hamstring under dual task condition compared with normal condition.(3)The limb asymmetries of peak knee flexion angle and knee flexion-extension ROM increased,while the limb asymmetries of hip adduction angle and ankle inversion-eversion ROM were smaller under dual task condition.Conclusions:(1)Patients 6 to 12 months after ACL reconstruction demonstrated significant kinematic and kinetic asymmetries between the surgical and nonsurgical limbs,and the activity of hamstring and the vastus lateralis-biceps femoris amplitude ratio were larger on operated side than on non-operated side.(2)Cognitive interventions reduced the range of motion of the lower limbs during walking and had a greater impact on the affected side.Cognitive intervention also reduced the amplitude of activation of hamstrings on the operated side,making it closer to normal.(3)The patients showed larger limb asymmetries of peak knee flexion angle and knee flexion-extension ROM,but smaller limb asymmetries of hip angle in frontal plane and ankle inversion-eversion ROM when patients walked performing a concurrent attention-demanding cognitive interference task.