External feedback during walking improves measures of plantar pressure in individuals with chronic ankle instability

Highlights

• Chronic ankle instability is known to cause gait alterations.

• Individuals with chronic ankle instability respond to external feedback while walking.

• External visual feedback improves plantar pressure measures.

Abstract

Background

Individuals with chronic ankle instability (CAI) commonly present with an altered walking gait which favors the lateral aspect of their foot. Current rehabilitative protocols are unable to address these gait modifications which are potentially hindering improvements in patient-reported outcomes. Protocols for gait retraining are scarce, thus there is a need to develop intervention strategies and instruments to specifically target foot motion to address gait deficits in individuals with CAI.

Research Question

To determine the ability of a novel laser device providing external visual feedback (ExFB) during real-time to cause alterations in plantar pressure measures in individuals with CAI.

Methods

Twenty-six participants with CAI walked on a treadmill while real-time plantar pressure measures were being recorded during a baseline and feedback condition. Baseline trials were compared with ExFB trials within each subject.

Results

The ExFB condition was able to significantly reduce plantar pressures on the lateral midfoot and forefoot compared to baseline. A statistically significant medial shift in center of pressure trajectory was also observed in the ExFB condition compared to baseline.

Significance

Real-time external feedback provided by a novel laser device has the ability to reduce lateral column plantar pressures during walking in individuals with CAI.

Introduction

Lateral ankle sprains (LAS) are considered the most common injury among physically activity people. [1] It has been projected 40% of individuals who sustain a LAS will continue to experience ankle dysfunction and go on to develop chronic ankle instability (CAI). [2] Individuals with CAI commonly exhibit a variety of clinical impairments such as compromised proprioception, [3] diminished static and dynamic balance, [4] and biomechanical alterations. [[5], [6], [7]] Specifically, people with CAI walk with increased ankle inversion and plantarflexion and laterally shifted plantar pressures and center of pressure (COP). [5,6] These precise biomechanical alterations correspond to the mechanism of injury for sustaining a LAS, potentially placing these individuals in a position predisposing them to sustain recurrent sprains and bouts of instability that are thought to contribute to the development of CAI.

Current rehabilitative approaches include strength, [8] balance, [8,9] and neuromuscular control [8] exercises in attempts at reducing the clinical impairments of this population. While these programs have been successful at reducing the severity of those impairments and improving patient-reported outcomes, [10] the associated biomechanical gait alterations remain unchanged. [[11], [12], [13]] Furthermore, the participants within these rehabilitation studies, still reported large deficits in self-reported ankle function. [8] It is hypothesized that the remaining deficits associated with self-reported function are partly attributed to the gait alterations that still exist in these patients. [8,12,14] Thus, it is recommended that gait retraining should be incorporated as an intervention for treating acute LAS and CAI. [9] While there is a need to incorporate gait retraining into an impairment-based rehabilitation program, there are limited gait retraining instruments and protocols specific for patients with CAI.

Previous research on patients with CAI has introduced auditory feedback [15] and a novel gait training device to reduce plantar pressure over the lateral column of the foot and shift COP medially. [16] While both studies successfully produced beneficial gait changes, the auditory feedback technology and gait retraining device may not be readily available to clinicians; therefore, other novel gait retraining instruments should continue to be developed and assessed.

Ideally, gait retraining instruments should be effective, low-cost, accessible by clinicians in a variety of settings, and employ the best motor learning strategies. Two strategies that exist to alter movement patterns are internal and external feedback. Internal feedback can be defined as focusing attention to the individuals body in order to consciously become aware of one’s performance. [17] Contrastingly, external feedback is defined as directing attention of the individuals’ movement in context of the environment [17]. The use of external visual feedback has been an effective mechanism for improving patient function and impairments following injury in individuals with various musculoskeletal injuries. [18]

External feedback may optimize sensory-motor loops via the central nervous system and successfully reinforce favorable repetitive actions. [18,19] Concurrent external visual feedback is able to increase fast, unconscious, and reflexive processes. [20] It is established that individuals with CAI have a compromised sensorimotor system [21] and heavily rely on visual afferent information for proprioceptive processing. [22] Current evidence [23] recognizes the inability of traditional balance training interventions to alter the visual reliance in individuals with CAI. However, external visual feedback being delivered in real time allowing for simultaneous visual and kinesthetic processing results in desired movements without instigating a reliance on the feedback. [24] Therefore, implementation of an external feedback tactic during a task such as walking should elicit beneficial results for patients with CAI.

Prior to establishing retention and prolonged effects of an external visual feedback intervention targeting gait changes in individuals with CAI, we must first determine if this population can respond to real-time external visual feedback during a task such as walking. In order to assure proper gait motions are being achieved during gait retraining, visual feedback strategies must provide accurate and precise reactions to movement. Laser pointers are well-known for guiding visual attention and widely used in other professional settings because of their accuracy. A laser beams’ low divergence should allow for a precise imitation of foot motion during walking and give accurate guidance to individuals attempting to respond to the visual movement of the beam. Therefore, the purpose of this investigation was to determine whether external visual feedback using a novel laser device can cause real-time alterations of plantar pressure measures during treadmill walking in individuals with CAI. We hypothesized the external feedback condition would reduce lateral plantar pressures and medially shift COP during walking.