The effect of dual tasking on the lower extremity kinematics during locomotion in patients with anterior cruciate ligament injury

Rapture of the anterior cruciate ligament (ACL) results into the changes in the movement patterns characterized by shorter stride length، greater step width and altered lower extremities biomechanics. As a result، gait pattern in ACL-injured patients may result in an attention demanding form of locomotion. Therefore، the aim of this study was to investigate the effects of cognitive dual tasking on the lower extremity kinematics during locomotion in patients with ACL rapture. Twenty men with ACL rapture and 20 men healthy controls walked on a treadmill at easy and difficult levels of gait and cognitive task difficulty. Sagittal plane joint angles at ankle، knee and hip joints in the 4 stages of gait cycle were analyzed in both study groups. The results revealed significant differences between involved limb of the patient group and matched limb of the control group for all 3 lower limb joints in the sagittal plane (p<0/05). In addition، there were significant differences between ankle، knee and hip joints of the involved and uninvolved limbs of the patient group in the most phases of gait cycle (p<0/05). Also، increasing cognitive task difficulty resulted into significant decrement of motion at ankle and knee joints in both study groups (p<0/05). The results of this study revealed that rapture of the ACL alters kinematic patterns of the involved limb relative to the uninvolved limb in the patient group. Also، dual tasking decreases distal joints motion (ankle and knee joints) so that they approach to the stable، closed pack positions. However، dual tasking did not result into the significant differences in the kinematic patterns of lower extremity joints in the sagittal plane between healthy and patient groups.