The learning process of gait retraining using real-time feedback in patients with medial knee osteoarthritis

Toe-in and toe-out gait retraining interventions to reduce proxy measures of medial knee joint load in people with medial knee osteoarthritis: Protocol for a randomised placebo-controlled trial

OBJECTIVE

Our primary aim is to determine the effect of a six-week toe-in, toe-out and active placebo gait retraining program on proxy measures of medial knee joint load and varus thrust in people with medial knee osteoarthritis. Our secondary aim is to determine the intervention effects on patient reported outcomes and physical function and determine if changes are maintained at three-months follow-up.

METHODS

We will conduct a three-arm randomised placebo-controlled trial. Ninety participants with medial knee osteoarthritis will be randomised and stratified via varus thrust status (presence/absence) to: toe-in, toe-out or placebo gait retraining (an intervention that does not change proxy measures of medial knee joint load). The intervention involves weekly clinician-supervised sessions with biofeedback, knee osteoarthritis education, motor learning and behaviour change principles, and daily gait retraining practice. Primary outcomes are proxy measures of medial knee joint load: knee adduction moment (early- and late-stance peaks and impulse), and varus thrust (presence/absence). Secondary outcomes include pain, physical function, medication and health care utilisation, quality of life, work ability, treatment blinding, intervention credibility and other biomechanical outcomes. Assessment timepoints are at baseline, six weeks (post intensive training), and three-months following the six-week intervention.

CONCLUSION

Our trial will determine whether toe-in or toe-out gait retraining is most effective at reducing proxy measures of medial knee joint load and varus thrust in people with medial knee osteoarthritis. This study will also evaluate if toe-in or toe-out gait retraining interventions are superior at improving pain, physical function and quality of life compared to placebo.

CLINICAL TRIAL REGISTRATION

This clinical trial protocol is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12621000414819).

The use of technology to support lifestyle interventions in knee osteoarthritis: A scoping review

Introduction

Technological tools that promote the adoption of physical activity to increase individuals' functional ability in knee osteoarthritis (OA) are desired to support lifestyle interventions. However, there is little consensus as to the current use of such supportive interventions for knee OA. The aim of this scoping review is therefore to provide an overview on the current use of technology within lifestyle interventions for individuals with knee OA.

Methods

Scoping review as per PRISMA guidance. Structured search of Cochrane Central Register for Controlled Trials, ELSEVIER, IEEExplore, GOOGLE Scholar, MEDLINE, PEDRO, PUBMED, WEB OF SCIENCE from 2010 to 2020 inclusive. Hits were screened by title and abstract and then full text review based on pre-defined criteria. Results were synthesised and pooled by theme for reporting.

Results

2508 papers were identified, and following review, 78 studies included. Papers included interventions for individuals with knee osteoarthritis (n ​= ​31), total or partial knee arthroplasty (n ​= ​20) and developmental work in healthy controls (n ​= ​27). Of the 78 studies, 47 were carried out in laboratory settings and 31 in the field. The identified themes included Movement measurement (n ​= ​24), Tele-rehabilitation (n ​= ​22), Biofeedback (n ​= ​20), Directly applied interventions (n ​= ​3), Virtual or augmented reality (n ​= ​5) and Machine learning (n ​= ​4).

Conclusions

The predominant current use of technology in OA lifestyle interventions is through well-established telecommunication and commercially available activity, joint angle and loading based measurement devices, while integrating new advanced technologies seems a longer-term goal. There is great potential for the engineering and clinical community to use technology to develop systems that offer real-time feedback to patients and clinician as part of rehabilitative interventions to inform treatment.

Predicting knee adduction moment response to gait retraining with minimal clinical data

Knee osteoarthritis is a progressive disease mediated by high joint loads. Foot progression angle modifications that reduce the knee adduction moment (KAM), a surrogate of knee loading, have demonstrated efficacy in alleviating pain and improving function. Although changes to the foot progression angle are overall beneficial, KAM reductions are not consistent across patients. Moreover, customized interventions are time-consuming and require instrumentation not commonly available in the clinic. We present a regression model that uses minimal clinical data—a set of six features easily obtained in the clinic—to predict the extent of first peak KAM reduction after toe-in gait retraining. For such a model to generalize, the training data must be large and variable. Given the lack of large public datasets that contain different gaits for the same patient, we generated this dataset synthetically. Insights learned from a ground-truth dataset with both baseline and toe-in gait trials (N = 12) enabled the creation of a large (N = 138) synthetic dataset for training the predictive model. On a test set of data collected by a separate research group (N = 15), the first peak KAM reduction was predicted with a mean absolute error of 0.134% body weight * height (%BW*HT). This error is smaller than the standard deviation of the first peak KAM during baseline walking averaged across test subjects (0.306%BW*HT). This work demonstrates the feasibility of training predictive models with synthetic data and provides clinicians with a new tool to predict the outcome of patient-specific gait retraining without requiring gait lab instrumentation.

Gait retraining is a conservative intervention for knee osteoarthritis shown to reduce pain and improve function. Although customizing a treatment plan for each patient results in a better therapeutic response, customization cannot yet be performed outside of the gait laboratory, preventing research advances from becoming part of clinical practice. Our work aimed to build a model that accurately predicts whether a patient with knee osteoarthritis will benefit from non-invasive gait retraining using measures that can be easily collected in the clinic. To overcome the lack of large datasets required to train predictive models, we generated data synthetically (N = 138) based on limited ground-truth examples, and we provide experimental evidence for the model’s ability to generalize to real data (N = 15). Our results contribute toward a future in which clinicians can use data collected in the clinic to easily identify patients who would respond to therapeutic gait retraining.

Gait modification with subject-specific foot progression angle in people with moderate knee osteoarthritis: Investigation of knee adduction moment and muscle activity

BACKGROUND

Subject-specific foot progression angle (SSFPA) as a personalized gait modification is a novel approach to specifically reducing knee adduction.

OBJECTIVE

This study aimed to investigate the effect of gait modification with SSFPA on the knee adduction moment and muscle activity in people with moderate knee osteoarthritis (KOA).

METHODS

In this clinical trial, nineteen volunteers with moderate KOA were instructed to walk in four different foot progression angle conditions (5° toe-out, 10° toe-out, 5° toe-in, and 10° toe-in) to determine SSFPA that caused the greatest reduction in the greater peak of the knee adduction moment (PKAM). Immediately and after 30 minutes of gait modification with SSFPA, peak root means square (PRMS) and medial and lateral co-contraction index (CCI) were evaluated in the knee muscles.

RESULT

Walking with 10° toe-in showed the most reduction in the greater PKAM (17.52 ± 15.39%) compared to 5° toe-in (7.1 ± 19.14%), 10° toe-out (1.26 ± 23.13%), and 5° toe-out (7.64 ± 16.71%). As the immediate effect, walking with SSFPA caused a 20.71 ± 12.07% reduction in the greater PKAM than the basic FPA (p < 0.001). After 30 minutes of gait retraining, the greater PKAM decreased by 10.36 ± 26.24%, but this reduction was not significant (p = 0.17). In addition, PRMS of lateral gastrocnemius increased (p = 0.04), and lateral CCI increased 10.72% during late stance (p = 0.04).

CONCLUSION

Our findings suggest the immediate effect of gait modification with SSFPA on decreasing the knee adduction moment. After gait retraining with SSFPA, the increase of lateral muscle co-contraction may enhance lateral knee muscle co-activity to unload the medial knee compartment. Clinical Trial Register Number: IRCT20101017004952N8.

Differences between adults and adolescents in responding to hip and knee pattern feedback during gait

Visual feedback techniques have shown potential in interventions aiming to retrain deviated gait patterns. Understanding the abilities of different age groups to modify their gait is needed to optimize interventions. Twelve adults (6F, 6 M; 26.3 ± 5.9 yrs.) and twelve adolescents (4F, 8 M; 13.6 ± 2.3 yrs) without disabilities participated in one training session. During the session, the responses to a visual kinematic feedback task in which one hip or knee target pattern was modified while unmodified target patterns were maintained in the other hip and knee joints were investigated. Limb orientation and acceleration data were collected using Inertial Measurement Units (IMU) (Xsens Awinda, Enschede, The Netherlands) with a sampling frequency of 60 Hz. Adults tended to outperform adolescents in tracking modified target patterns and showed smaller errors in unmodified regions of modified patterns (p = 0.045); they also outperformed adolescents in unmodified joints (Contralateral Hip: p = 0.003; Contralateral Knee: p = 0.002; Ipsilateral Joint: p = 0.048). These findings suggest different levels of awareness of the need and/or ability to minimize errors across joints, in turn suggesting the need for specialization of training for these age groups.

Trunk lean and toe out gait strategies impact on lower limb joints

Gait retraining as a non-invasive prospective approach to restore mechanical loading at the knee joint and slowing down knee osteoarthritis (OA) progression shows great promise. However, the impact of gait modifications such as an increase in foot progression angle (FPA) or lateral trunk lean (LTL) on the ankle and hip is not yet well understood. Thus, the goal of this study is to provide insight on the impact of FPA and LTL on the sagittal and frontal external moments at the ankle and hip of healthy participants. We hypothesize that there is an optimum, for which an increase in FPA and/or LTL minimize the knee adduction moment (KAM) without increasing significantly the frontal and sagittal external moments at the ankle and hip during gait. To test this hypothesis, 23 participants performed walking trials with modified FPA and/or LTL angles following a real-time visual feedback. The hypothesis was not confirmed and while not all the gait modifications performed by the participants in this study reduced the KAM, they significantly increased the sagittal moment at the ankle and the frontal moment at the hip. This study highlights the importance to consider the biomechanical consequences of gait modifications on the ankle and hip before considering a clinical application of gait retraining approaches.

Conservative interventions to improve foot progression angle and clinical measures in orthopedic and neurological patients - A systematic review and meta-analysis

To establish the comparative effects of conservative interventions on modifying foot progression angle (FPA) in children and adults with orthopaedic and neurological disease was the main aim of the literature review. Pubmed, Embase, Cinahl, and Web of Science were systematically searched for studies evaluating the effects of conservative interventions on correcting the FPA. The study protocol was registered with PROSPERO (CRD42020143512). Two reviewers independently assessed studies for inclusion and quality. Studies that assessed conservative interventions that could have affected the FPA and objectively measured the FPA were included. Within group Mean Differences (MD) and Standardized Mean Differences (SMDs) of the interventions were calculated for the change in FPA and gait performance (walking speed, stride/step length) and clinical condition (pain). Intervention effects on FPA were synthesized via meta-analysis or qualitatively. 41 studies were identified. For patients with knee osteoarthritis gait training interventions (MD = 6.69° and MD = 16.06°) were significantly more effective than mechanical interventions (MD = 0.44°) in modifying the FPA towards in-toeing (p < 0.00001). Increasing or decreasing the FPA significantly improved pain in patients with medial knee OA. Results were inconclusive for the effectiveness of gait training and mechanical devices in patients with neurological diseases. Gait feedback training is more effective than external devices to produce lasting improvements in FPA, reduce pain, and maintain gait performance in patients with medial knee OA. However, in neurological patients, the effects of external devices on improvements in FPA depends on the interaction between patient-specific impairments and the technical properties of the external device.

Inertial measurement units and application for remote healthcare in hip and knee osteoarthritis: a narrative review (Preprint)

Background

Measuring and modifying movement-related joint loading is integral to the management of lower extremity osteoarthritis (OA). Although traditional approaches rely on measurements made within the laboratory or clinical environments, inertial sensors provide an opportunity to quantify these outcomes in patients’ natural environments, providing greater ecological validity and opportunities to develop large data sets of movement data for the development of OA interventions.

Objective

This narrative review aimed to discuss and summarize recent developments in the use of inertial sensors for assessing movement during daily activities in individuals with hip and knee OA and to identify how this may translate to improved remote health care for this population.

Methods

A literature search was performed in November 2018 and repeated in July 2019 and March 2021 using the PubMed and Embase databases for publications on inertial sensors in hip and knee OA published in English within the previous 5 years. The search terms encompassed both OA and wearable sensors. Duplicate studies, systematic reviews, conference abstracts, and study protocols were also excluded. One reviewer screened the search result titles by removing irrelevant studies, and 2 reviewers screened study abstracts to identify studies using inertial sensors as the main sensing technology and a primary outcome related to movement quality. In addition, after the March 2021 search, 2 reviewers rescreened all previously included studies to confirm their relevance to this review.

Results

From the search process, 43 studies were determined to be relevant and subsequently included in this review. Inertial sensors have been successfully implemented for assessing the presence and severity of OA (n=11), assessing disease progression risk and providing feedback for gait retraining (n=7), and remotely monitoring intervention outcomes and identifying potential responders and nonresponders to interventions (n=14). In addition, studies have validated the use of inertial sensors for these applications (n=8) and analyzed the optimal sensor placement combinations and data input analysis for measuring different metrics of interest (n=3). These studies show promise for remote health care monitoring and intervention delivery in hip and knee OA, but many studies have focused on walking rather than a range of activities of daily living and have been performed in small samples (<100 participants) and in a laboratory rather than in a real-world environment.

Conclusions

Inertial sensors show promise for remote monitoring, risk assessment, and intervention delivery in individuals with hip and knee OA. Future opportunities remain to validate these sensors in real-world settings across a range of activities of daily living and to optimize sensor placement and data analysis approaches.

Wearable Real-Time Haptic Biofeedback Foot Progression Angle Gait Modification to Assess Short-Term Retention and Cognitive Demand

Foot progression angle gait (FPA) modification is an important part of rehabilitation for a variety of neuromuscular and musculoskeletal diseases. While wearable haptic biofeedback could enable FPA gait modification for more widespread use than traditional tethered, laboratory-based approaches, retention, and cognitive demand in FPA gait modification via wearable haptic biofeedback are currently unknown and may be important to real-life implementation. Thus, the purpose of this study was to assess the feasibility of wearable haptic biofeedback to assess short-term retention and cognitive demand during FPA gait modification. Ten healthy participants performed toe-in (target 10 degrees change in internal rotation) and toe-out (target 10 degrees change in external rotation) haptic gait training trials followed by short-term retention trials, and cognitive multitasking trials. Results showed that participants were able to initially respond to the wearable haptic feedback to modify their FPA to adopt the new toe-in (9.7 ± 0.8 degree change in internal rotation) and toe-out (8.9 ± 1.0 degree change in external rotation) gait patterns. Participants retained the modified gait pattern on average within 3.9 ± 3.6 deg of the final haptic gait training FPA values. Furthermore, cognitive multitasking did not influence short-term retention in that there were no differences in gait performance during retention trials with or without cognitive multitasking. These results demonstrate that wearable haptic biofeedback can be used to assess short-term retention and cognitive demand during FPA gait modification without the need for traditional, tethered systems.

Effects of real-time feedback during decline walking on kinematic and kinetic gait parameters in a healthy population: study protocol for a randomized trial - up and down

BACKGROUND

The control of the dynamic functional leg alignment (dFLA) and biomechanical load are important joint-related aspects regarding the development of osteoarthritis (OA). Research on level walking with feedback on load-related parameters has provided innovative treatment possibilities. With regard to walking on sloped surfaces, fundamental biomechanical knowledge exists. However, comprehensive data on the agreement of kinematics and kinetics of self-paced ramp versus sloped treadmill walking is lacking. Further, deeper insights into the control of the dFLA during decline walking and the usefulness of real-time feedback are missing.

METHODS/DESIGN

Thirty healthy participants aged between 18 and 35 years will be included. They will complete a three-dimensional gait analysis walking self-paced up and down on a 5-m ramp with a 10° inclination. Subsequently, speed-matched to ramp-up walking and self-paced 10° incline split-belt treadmill walking will be assessed. Afterwards, the participants will be observed under four different conditions of 10° declined walking on the same treadmill (a) self-paced walking, (b) self-paced walking with an internal focus of attention, (c) self-paced walking with real-time feedback, and (d) condition c speed-matched walking. The primary outcome parameter will be the frontal knee range of motion (fKROM). Secondary outcomes include the ground reaction force loading rate, spatial-temporal parameters, as well as sagittal, frontal and transversal kinematics, and kinetics for the lower extremities.

DISCUSSION

The findings aim at improving the understanding of the effects of real-time feedback on the control of the dFLA and lower limb loading. Following clinical practicable methods for effective feedback devices can be developed and evaluated. Additionally, the first dataset comparing kinematic and kinetic parameters for decline and incline ramp walking versus walking on an instrumented treadmill will be available for appropriate intervention planning.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04763850 . Prospectively registered on 21 February 2021.

Effects of biofeedback on whole lower limb joint kinematics and external kinetics

Biofeedback (BFb) is a useful tool to accelerate the skill development process. Limited research has applied BFb to the whole lower-limb in a complex skill therefore the aim of this research was to assess the effectiveness of a biofeedback intervention targeting whole lower limb kinematics. Thirty-two healthy participants were randomized to a BFb (n = 16) and a Control group (n = 16). Participants visited a motion capture laboratory on three occasions during one week, and returned for retention testing at 4-6 weeks. Following introduction to a novel lunge-touch task, visual BFb on lower limb joint kinematic extension angular velocities (ω) and timing were provided following each lunge. BFb was effective in increasing Hipω (F = 3.746, p = 0.03) and Kneeω (F = 10.241, p = 0.01). Peak Ankle_ω remained unchanged (F = 1.537, p = 0.23, η² = 0.05), however Peak Ankle_θ (F = 10.915, p < 0.001, η² = 0.27) and Ankle_ROM (F = 9.543, p < 0.001, η² = 0.24) significantly increased. Despite kinematic changes, there were no significant changes in any external kinetics. No significant correlations were found between Hipω, Kneeω or Ankleω and horizontal impulse (Impulse_Y: r = 0.20, p = 0.26; r = -0.11, p = 0.24; and r = 0.22, p = 0.28, respectively). Findings demonstrate that BFb can be used to alter multiple kinematic variables in a complex skill, but do not necessarily alter associated kinetic variables not directly targeted by BFb.

Foot progression angle estimation using a single foot-worn inertial sensor

Background

The foot progression angle is an important measure used to help patients reduce their knee adduction moment. Current measurement systems are either lab-bounded or do not function in all environments (e.g., magnetically distorted). This work proposes a novel approach to estimate foot progression angle using a single foot-worn inertial sensor (accelerometer and gyroscope).

Methods

The approach uses a dynamic step frame that is recalculated for the stance phase of each step to calculate the foot trajectory relative to that frame, to minimize effects of drift and to eliminate the need for a magnetometer. The foot progression angle (FPA) is then calculated as the angle between walking direction and the dynamic step frame. This approach was validated by gait measurements with five subjects walking with three gait types (normal, toe-in and toe-out).

Results

The FPA was estimated with a maximum mean error of ~ 2.6° over all gait conditions. Additionally, the proposed inertial approach can significantly differentiate between the three different gait types.

Conclusion

The proposed approach can effectively estimate differences in FPA without requiring a heading reference (magnetometer). This work enables feedback applications on FPA for patients with gait disorders that function in any environment, i.e. outside of a gait lab or in magnetically distorted environments.

Learning Gait Modifications for Musculoskeletal Rehabilitation: Applying Motor Learning Principles to Improve Research and Clinical Implementation

Gait modifications are used in the rehabilitation of musculoskeletal conditions like osteoarthritis and patellofemoral pain syndrome. While most of the research has focused on the biomechanical and clinical outcomes affected by gait modification, the process of learning these new gait patterns has received little attention. Without adequate learning, it is unlikely that the modification will be performed in daily life, limiting the likelihood of long-term benefit. There is a vast body of literature examining motor learning, though little has involved gait modifications, especially in populations with musculoskeletal conditions. The studies that have examined gait modifications in these populations are often limited due to incomplete reporting and study design decisions that prohibit strong conclusions about motor learning. This perspective draws on evidence from the broader motor learning literature for application in the context of modifying gait. Where possible, specific gait modification examples are included to highlight the current literature and what can be improved on going forward. A brief theoretical overview of motor learning is outlined, followed by strategies that are known to improve motor learning, and finally, how assessments of learning need to be conducted to make meaningful conclusions.

The effect of changing mediolateral center of pressure on rearfoot eversion during treadmill running

INTRODUCTION

Atypical rearfoot eversion is an important kinematic risk factor in running-related injuries. Prominent interventions for atypical rearfoot eversion include foot orthoses, footwear, and taping, yet a running gait retraining is lacking. Therefore, the aim was to investigate the effects of changing mediolateral center of pressure (COP) on rearfoot eversion, subtalar pronation, medial longitudinal arch angle (MLAA), hip kinematics and vertical ground reaction force (vGRF).

METHODS

Fifteen healthy female runners underwent gait retraining under three conditions. Participants were instructed to run normally, on the lateral (COP lateral) and medial (COP medial) side of the foot. Foot progression angle (FPA) was controlled using real-time visual feedback. 3D measurements of rearfoot eversion, subtalar pronation, MLAA, FPA, hip kinematics, vGRF and COP were analyzed. A repeated-measures ANOVA followed by pairwise comparisons was used to analyze changes in outcome between three conditions. Data were also analyzed using statistic parameter mapping.

RESULTS

Running on the lateral side of the foot compared to normal running and running on the medial side of the foot reduced peak rearfoot eversion (mean difference (MD) with normal 3.3°, p < 0.001, MD with COP medial 6°, p < 0.001), peak pronation (MD with normal 5°, p < 0.001, MD with COP medial 9.6°, p=<0.001), peak MLAA (MD with normal 2.3°, p < 0.001, MD with COP medial 4.1°, p < 0.001), peak hip internal rotation (MD with normal 1.8°, p < 0.001), and peak hip adduction (MD with normal running 1°, p = 0.011). Running on the medial side of the foot significantly increased peak rearfoot eversion, pronation and MLAA compared to normal running.

SIGNIFICANCE

This study demonstrated that COP translation along the mediolateral foot axis significantly influences rearfoot eversion, MLAA, and subtalar pronation during running. Running with either more lateral or medial COP reduced or increased peak rearfoot eversion, peak subtalar pronation, and peak MLAA, respectively, compared to normal running. These results might use as a basis to help clinicians and researchers prescribe running gait retraining by changing mediolateral COP for runners with atypical rearfoot eversion or MLAA.

Modeling and Prediction of Wearable Energy Harvesting Sliding Shoes for Metabolic Cost and Energy Rate Outside of the Lab

The recent explosion of wearable electronics has led to widespread interest in harvesting human movement energy, particularly during walking, for clinical and health applications. However, the amount of energy available to harvest and the required metabolic rate for wearable energy harvesting varies across subjects. In this paper, we utilize custom energy harvesting sliding shoes to develop and evaluate multivariate linear regression models to predict metabolic rate and energy harvesting rate during overground walking outside of the lab. Subjects performed 200 m self-selected normal and fast walking trials on flat ground with custom sliding shoes. Metabolic rate was measured with a portable breathing analysis system and energy harvesting rate was measured directly from the generator on the custom sliding shoes. Model performance was determined by comparing the difference between actual and predicted metabolic and energy harvesting rates. Overall, predictive modeling closely matched the actual values, and there was no statistical difference between actual and predicted average metabolic rate or between actual and predicted average energy harvesting rate. Energy harvesting sliding shoes could potentially be used for a variety of wearable devices to reduce onboard energy storage, and these findings could serve to inform expected energy harvesting rates and associated required metabolic cost for a diverse array of medical and health applications.

Decreasing the ambulatory knee adduction moment without increasing the knee flexion moment individually through modifications in footprint parameters: A feasibility study for a dual kinetic change in healthy subjects

Gait retraining is gaining in interest to reduce loading associated to knee osteoarthritis (OA) progression. So far, interventions focused on reducing the peak knee adduction moment (pKAM) and it remains unclear if this can be done individually without increasing the peak knee flexion moment (pKFM). Additionally, while modifying foot progression angle (FPA) and step width (SW) is common, little is known about modifications in stride length (SL). This study aimed at characterizing the feasibility of a dual kinetic change, consisting in reducing the pKAM by at least 10% without increasing the pKFM. It also aimed to evaluate the added value of SL modifications in achieving the dual kinetic change. Gait trials with modifications in FPA, SW and SL were recorded for 11 young healthy subjects in a laboratory equipped with an augmented-reality system displaying instruction footprints on the floor. All participants achieved the dual kinetic change with at least one of the modifications. Seven participants achieved it with FPA modification, three with SW modification, and seven with SL modification. In conclusion, this study showed that it is feasible to achieve the dual kinetic change individually through subject-specific modifications in footprint parameters, suggesting that, in the future, gait retraining could aim for more specific kinetic changes than simply pKAM reductions. Modifying SL allowed achieving the dual kinetic change, stressing out the value of this parameter for gait retraining, in addition to FPA and SW. Finally, an augmented-reality approach was introduced to help footprint parameter modifications in the framework of knee OA.

Real-time visual feedback reduces patellofemoral joint forces during squatting in individuals with patellofemoral pain

BACKGROUND

Elevated patellofemoral joint forces appear to contribute to the development of patellofemoral pain. As a result, treatment of patellofemoral pain often includes movement retraining intended to reduce patellofemoral joint forces. Real-time visual feedback has been shown to be effective for retraining running kinematics; however, we are not aware of a previous study that has examined the influence of real-time visual feedback on patellofemoral joint mechanics during a squat.

METHODS

Twenty individuals with patellofemoral pain completed squats before (baseline) and immediately after (post-feedback) completing a real-time visual feedback training session. During the session, participants received visual feedback related to their patellofemoral joint forces (estimated via a musculoskeletal model) during squatting and were asked to alter their movement pattern to minimize these forces. Patellofemoral joint forces and hip, knee, and ankle joint mechanics were compared for the baseline and post-feedback trials in order to examine how feedback influenced squat performance.

FINDINGS

Participants demonstrated a 14.4% reduction in patellofemoral joint forces following the feedback session. They appeared to achieve this reduction in patellofemoral joint forces by squatting with less knee flexion (97.26 ± 17.11° vs. 102.96 ± 16.55°) and lower knee extension moments (0.10 ± 0.02 Nm/bodyweight vs. 0.11 ± 0.02 Nm/bodyweight) and quadriceps forces (4.06 ± 0.87 bodyweights vs. 4.67 ± 0.98 bodyweights).

INTERPRETATION

Real-time visual feedback appears to be effective for reducing patellofemoral joint forces during squatting in individuals with patellofemoral pain. As a result, training of this nature may be beneficial when treating patellofemoral pain.

Portable, automated foot progression angle gait modification via a proof-of-concept haptic feedback-sensorized shoe

Modifying the foot progression angle (FPA) is a non-pharmacological, non-surgical treatment option for knee osteoarthritis, however current widespread adoption has been limited by the requirement of laboratory-based motion capture systems. We present the first customized haptic feedback-sensorized shoe for estimating and modifying FPA during walking gait, which includes an electronic inertial and magnetometer module in the sole for estimating FPA, and two vibration motors attached to the medial and lateral shoe lining for providing vibrotactile feedback. Feasibility testing was performed by comparing FPA performance while wearing the haptic feedback-sensorized shoe with the training targets. Participants performed five walking trials with five randomly-presented FPA targets (10° toe-in, 0°, 10° toe-out, 20° toe-out, and 30° toe-out) of 2 min each on a treadmill. Overall average FPA performance error across all conditions was 0.2 ± 4.1°, and the overall mean absolute FPA performance error across all conditions was 3.1 ± 2.6°. Reducing the size of the no-feedback window resulted in less performance error during walking. This study demonstrates that a novel haptic feedback-sensorized shoe can be used to effectively train FPA modifications. The haptic feedback-sensorized shoe could potentially be used for FPA gait modification outside of specialized camera-based motion capture laboratories as a conservative treatment for knee osteoarthritis or other related clinical applications requiring FPA assessment and modification in daily life.

Dual-Task Effects on Performance of Gait and Balance in People with Knee Pain: A Systematic Scoping Review

Dual-task paradigms have been increasingly used to assess the interaction between cognitive demands and the control of balance and gait. The interaction between functional and cognitive demands can alter movement patterns and increase knee instability in individuals with knee conditions, such as knee anterior cruciate ligament (ACL) injury or osteoarthritis (OA). However, there is no consensus on the effects of dual-task on gait mechanics and balance in those individuals. This systematic scoping review aims to examine the impact of dual-task gait and standing balance on motor and cognitive performance in individuals with knee OA or ACL injury. A comprehensive search of MEDLINE, PubMed, Web of Science, and EMBASE electronic databases up until December 2019 was carried out. Inclusion criteria was limited to include dual-task studies that combined cognitive tasks performed simultaneously with gait or standing balance in individuals with knee OA or ACL injuries. In total, fifteen studies met the inclusion criteria, nine articles examined dual-task effects on balance, and six articles reported the effects of dual-task on gait. The total number of individuals included was 230 individuals with ACL injuries, and 168 individuals with knee OA. A decline in gait and balance performance during dual-task testing is present among individuals with ACL injury and/or ACL reconstruction and knee OA. Further research is required, but dual taking assessment could potentially be used to identify individuals at risk of falling or further injury and could be used to develop targeted rehabilitation protocols. A variety of outcome measures have been used across the studies included, making comparisons difficult. The authors, therefore, recommend developing a standardized set of biomechanical balance variables.

Effect of walking with a modified gait on activation patterns of the knee spanning muscles in people with medial knee osteoarthritis

OBJECTIVE

To evaluate muscle activation patterns and co-contraction around the knee in response to walking with modified gait patterns in patients with medial compartment knee-osteoarthritis (KOA).

DESIGN

40 medial KOA patients walked on an instrumented treadmill. Surface EMG activity from seven knee-spanning muscles (gastrocnemius, hamstrings, quadriceps), kinematics, and ground reaction forces were recorded. Patients received real-time visual feedback on target kinematics to modify their gait pattern towards three different gait modifications: Toe-in, Wider steps, Medial Thrust. The individualized feedback aimed to reduce their first peak knee adduction moment (KAM) by ≥10%. Changes in muscle activations and medial/lateral co-contraction index during the loading response phase (10-35% of the gait cycle) were evaluated, for the steps in which ≥10% KAM reduction was achieved.

RESULTS

Data from 30 patients were included in the analyses; i.e. all who could successfully reduce their KAM in a sufficient number of steps by ≥10%. When walking with ≥10% KAM reduction, Medial Thrust gait (KAM -31%) showed increased flexor activation (24%), co-contraction (17%) and knee flexion moment (35%). Isolated wider-step gait also reduced the KAM (-26%), but to a smaller extent, but without increasing muscle activation amplitudes and co-contraction. Toe-in gait showed the greatest reduction in the KAM (-35%), but was accompanied by an increased flexor activation of 42% and hence an increased co-contraction index.

CONCLUSION

Gait modifications that are most effective in reducing the KAM also yield an increase in co-contraction, thereby compromising at least part of the effects on net knee load.

The validity and usability of an eight marker model for avatar-based biofeedback gait training

BACKGROUND

Virtual reality presents a platform for therapeutic gaming, and incorporation of immersive biofeedback on gait may enhance outcomes in rehabilitation. Time is limited in therapeutic practice, therefore any potential gait training tool requires a short set up time, while maintaining clinical relevance and accuracy. The aim of this study was to develop, validate, and establish the usability of an avatar-based application for biofeedback-enhanced gait training with minimal set up time.

METHODS

A simplified, eight marker model was developed using eight passive markers placed on anatomical landmarks. This allowed for visualisation of avatar-based biofeedback on pelvis kinematics, hip and knee sagittal angles in real-time. Retrospective gait analysis data from typically developing children (n = 41) and children with cerebral palsy (n = 25), were used to validate eight marker model. Gait outcomes were compared to the Human Body Model using statistical parametric mapping. Usability for use in clinical practice was tested in five clinical rehabilitation centers with the system usability score.

FINDINGS

Gait outcomes of Human Body Model and eight marker model were comparable, with small differences in gait parameters. The discrepancies between models were <5°, except for knee extension where eight marker model showed significantly less knee extension, especially towards full extension. The application was considered of 'high marginal acceptability' (system usability score, mean 68 (SD 13)).

INTERPRETATION

Gait biofeedback can be achieved, to acceptable accuracy for within-session gait training, using an eight marker model. The application may be considered usable and implemented for use in patient populations undergoing gait training.

Quantifying bi-variate coordination variability during longitudinal motor learning of a complex skill

Biofeedback (BFb) can enhance the motor learning process by guiding skill exploration. Too much BFb, however, can foster dependency leading to skill retention deficits once removed. A reducing BFb schedule could negate dependency effects, however limited methodologies exist to assess the effectiveness of an intervention during application. This research proposes a new bi-variate method (CI2_Area) to quantify coordination variability (Coord_Var) as a measure of skill exploration during a motor learning intervention. Thirty-two participants were introduced to a novel explosive-lunge task. A BFb group (n = 16) were provided with visual BFb on rear hip, knee and ankle joint extension magnitudes and timing during a 26-week reducing schedule BFb intervention. Coord_Var of hip-knee and knee-ankle angular velocities were quantified by calculating the area encompassed by the 95% confidence intervals of joint coupling angular-velocity bi-variate plots (CI2_Area). Linear regressions were fitted to group and individual Coord_Var longitudinal data. The BFb was effective in successfully altering whole limb technique within just two sessions, and these changes were retained. The BFb group demonstrated a continual increase of Coord_Var throughout the intervention, showing continual skill exploration strategies, while the Control group remained unchanged. Gradually increasing time between sessions, using a longitudinally reducing BFb schedule, successfully negates dependency effects on BFb while also encouraging motor learning. Manipulating time between sessions allows for the provision of a high frequency of 100% BFb without fostering dependency. The CI2_Area method was able to detect individual exploration strategies and could be used in the future to direct individual intervention modifications.

Sagittal plane walking biomechanics in individuals with knee osteoarthritis after quadriceps strengthening

OBJECTIVE

To compare sagittal walking gait biomechanics between participants with knee osteoarthritis (KOA) who increased quadriceps strength following a lower-extremity strengthening intervention (responders) and those who did not increase strength following the same strengthening protocol (non-responders) both at baseline and following the lower extremity strengthening protocol.

DESIGN

Fifty-three participants with radiographic KOA (47% female, 62.3 ± 7.1 years, BMI = 28.5 ± 3.9 kg/m²) were enrolled in 10 sessions of lower extremity strengthening over a 28-day period. Maximum isometric quadriceps strength and walking gait biomechanics were collected on the involved limb at baseline and 4-weeks following the strengthening intervention. Responders were classified as individuals who increased quadriceps strength greater than the upper limit of the 95% confidence interval (CI) for the minimal detectable change (MDC) in quadriceps strength (29 Nm) determined in a previous study. 2 × 2 functional analyses of variance were used to evaluate the effects of group (responders and non-responders) and time (baseline and 4-weeks) on time-normalized waveforms for knee flexion angle (KFA), vertical ground reaction force (vGRF), and internal knee extension moment (KEM).

RESULTS

A significant group x time interaction for KFA demonstrated greater KFA in the first half of stance at baseline and greater knee extension in the second half of stance at 4-weeks in responders compared to non-responders. There was no significant group x time interaction for vGRF or internal KEM.

CONCLUSIONS

Quadriceps strengthening may be used to stimulate small changes in KFA in individuals with KOA.

Unsupervised gait retraining using a wireless pressure-detecting shoe insole

BACKGROUND

The knee adduction moment (KAM) is a surrogate measure of mediolateral distribution of loads across the knee joint and is correlated with progression and severity of knee osteoarthritis (OA). Existing biomechanical approaches for unloading the arthritic medial knee compartment vary in their effectiveness in reducing KAM. This study employed a completely wireless, pressure-detecting shoe insole capable of generating auditory feedback via a smartphone.

RESEARCH QUESTION

To investigate whether auditory cues from a smartphone can prompt subjects to adjust their gait pattern and reduce KAM.

METHODS

Nineteen healthy subjects underwent gait training inside the lab (Phase 1) and received auditory cues during mid- and terminal stance to medialize their foot COP (center-of-pressure). This initial training period was continued unsupervised while walking around campus (Phase 2).

RESULTS

After Phase 1, subjects reduced their KAM by 20.6% (p =  0. 001), a finding similar to a previous study that used a wired, lab-based insole system. After further unsupervised training outside the lab during Phase 2, subjects were able to execute the newly learned gait pattern without auditory feedback still showing a KAM reduction of 17.2% (p <  0.001). Although, speed at Phase 2 was lower than at baseline (p =  0.013), this reduction had little effect on KAM (r = 0.297, p =  0.216). In addition, the adduction angular impulse was reduced (p =  0.001), despite the slower speed.

SIGNIFICANCE

Together, these results suggest that the wireless insole is a promising tool for gait retraining to lower the KAM and will be implemented in a home-based clinical trial of gait retraining for subjects with knee OA.

Validation of wearable visual feedback for retraining foot progression angle using inertial sensors and an augmented reality headset

Background

Gait retraining interventions using real-time biofeedback have been proposed to alter the loading across the knee joint in patients with knee osteoarthritis. Despite the demonstrated benefits of these conservative treatments, their clinical adoption is currently obstructed by the high complexity, spatial demands, and cost of optical motion capture systems. In this study we propose and evaluate a wearable visual feedback system for gait retraining of the foot progression angle (FPA).

Methods

The primary components of the system are inertial measurement units, which track the human movement without spatial limitations, and an augmented reality headset used to project the visual feedback in the visual field. The adapted gait protocol contained five different target angles ranging from 15 degrees toe-out to 5 degrees toe-in. Eleven healthy participants walked on an instrumented treadmill, and the protocol was performed using both an established laboratory visual feedback driven by optical motion capture, and the proposed wearable system.

Results and conclusions

The wearable system tracked FPA with an accuracy of 2.4 degrees RMS and ICC=0.94 across all target angles and subjects, when compared to an optical motion capture reference. In addition, the effectiveness of the biofeedback, reflected by the number of steps with FPA value ±2 degrees from the target, was found to be around 50% in both wearable and laboratory approaches. These findings demonstrate that retraining of the FPA using wearable inertial sensing and visual feedback is feasible with effectiveness matching closely an established laboratory method. The proposed wearable setup may reduce the complexity of gait retraining applications and facilitate their transfer to routine clinical practice.