Bilateral electromyogram response latency following platform perturbation in unilateral transtibial prosthesis users: Influence of weight distribution and limb position

Abstract

Abstract-Appropriate muscular response following an external perturbation is essential in preventing falls. Transtibial prosthesis users lack a foot-ankle complex and associated sensorimotor structures on the side with the prosthesis. The effect of this lack on rapid responses of the lower limb to external surface perturbations is unknown. The aim of the present study was to compare electromyogram (EMG) response latencies of otherwise healthy, unilateral, transtibial prosthesis users (n = 23, mean +/-standard deviation [SD] age = 48 +/-14 yr) and a matched control group (n = 23, mean +/-SD age = 48 +/-13 yr) following sudden support-surface rotations in the pitch plane (toes-up and toes-down). Perturbations were elicited in various weight-bearing and limb-perturbed conditions. The results indicated that transtibial prosthesis users have delayed responses of multiple muscles of the lower limb following perturbation, both in the intact and residual limbs. Weight-bearing had no influence on the response latency in the residual limb, but did on the intact limb. Which limb received the perturbation was found to influence the muscular response, with the intact limb showing a significantly delayed response when the perturbation was received only on the side with a prosthesis. These delayed responses may represent an increased risk of falling for individuals who use transtibial prostheses.

Adaptations from the prosthetic and intact limb during standing on a sway-referenced support surface for transtibial prosthesis users

“…Efforts have been made to identify the individual biomechanical role the prosthesis and intact limbs play in postural control and postural stability [7][8][9][10][11][12][13][14][15][16][17][18]. Often, these methods rely on extracting information about postural stability via displacement of the centre of pressure (CoP) [19].…”

Individuals with transtibial limb loss use interlimb force asymmetries to maintain multi-directional reactive balance control

“…These responses were much larger on the intact side of the body, and frequently absent on the side affected by limb loss [23]. In response to external perturbations, individuals with unilateral TTLL exhibit delayed muscle responses in both the intact and prosthetic leg [24], as well as greater reliance on the intact versus prosthetic leg to generate corrective responses (i.e. CoP displacement, ankle torque) [25–27].…”

“…In these prior studies, perturbations were often limited to the sagittal plane [9,24–26]. Sagittal plane perturbations load both legs, allowing participants to compensate for sensorimotor impairment in one leg by using the contralateral leg more.…”

Portable haptic device for lower limb amputee gait feedback: Assessing static and dynamic perceptibility

“…Prescription of prosthetic device post amputation is intended to help restore some degrees of mobility function, however studies have shown evidence of low balance confidence and higher risk of falling among amputee community, especially those suffering from above knee amputation [2] - [3]. The lack of response to external perturbation can be attributed to loss of sensorimotor post amputation [4], which reduces limb control during mobility. While powered prosthesis offers better control of prosthetic device, they often lack a form of feedback which creates awareness of the limb position to the user while walking.…”