The effect of perturbation on hip kinematics of transtibial amputees

Abstract

Gait adaptation to perturbations is essential for safe interaction with the physical environment and therefore it is important to understand how people with lower-limb amputation adapt their gait to changing conditions (1). Previous studies tried to find some deviation patterns and understand the kinematic strategies of amputee's gait (2). However, there is limited information available on the hip kinematics of amputees during gait and there is no study has yet investigated the effect of the perturbation on the hip kinematics of amputees. How does unpredictable continuous perturbation during gait affect the hip kinematics of unilateral transtibial amputees? Individuals with unilateral trans-tibial amputations and using prostheses with an active vacuum plus carbon foot combination were included in to study. Kinematic data of the hip were collected from 11 amputees and 10 healthy controls during walking on two different ground conditions. Participants walked at least 512 steps at their preferred speed on a motorized treadmill’s (ReaxRun Pro) flat ground condition and then the gait analysis was repeated on a perturbed (5% unpredictable perturbation) ground condition. RehaGait- Pro system was used for evaluation of the kinematics of the hip(min-max hip angles and variability of the hip min-max angles) during gait. Negative values indicated hip hyperextension, positive values indicated hip flexion. The statistical analysis was performed by pairing the residual limbs of amputees with the non-dominant side of the healthy group (RL side), and the sound limbs with the dominant side of the healthy group (HL side). It was observed that the hip hyperextension angle on the sound limb side was bigger in the amputees than in the control group on flat (d=0.462; p=0.034) and perturbated ground (d=0.584; p=0.007). The effect size was larger on the perturbed ground. There was no difference in the maximum hip angles and variability of max-min hip angles between the groups in both ground conditions (p>0.05). The results showed in Table.Download : Download high-res image (142KB)Download : Download full-size image Amputation-related changes were observed in hip kinematics during walking under both ground conditions. However, this change was more prominent on the perturbated ground. The reason for the higher hip hyperextension values in amputees is thought to be due to their efforts to compensate for the ankle (exp. strong plantar flexion) movements. On the unpredictable perturbation ground, the limitation of ankle movements, which is one of the first adaptive mechanisms in adaptation to the ground (exp. subtalar rotations plus plantarflexion), may have made the situation more evident. Future studies may focus on the effect of gait training on perturbed surfaces on gait kinematics, which is an indicator of adaptation to variable conditions.