Older adults who have previously fallen due to a trip walk differently than those who have fallen due to a slip

Investigating the Effects of a Kinematic Gait Parameter-Based Haptic Cue on Toe Clearance in Parkinson's Patients

Recurrent falls pose a significant challenge for Parkinson's disease (PD) patients and are a leading cause of disability in this population. One contributing factor to these recurring falls is the reduced minimum toe clearance (mTC). Preventing such falls by enhancing mTC has become an important goal in gait training among PD patients. In this paper, we propose a wearable cueing-based novel gait training device in anticipation of improved mTC. The cueing device records the foot strike angle (FSA) and cues the participants if the FSA is observed above a threshold. The patients with PD (n = 8) were recruited and asked to walk under two conditions: (a) with cue and (b) without cue at a self-selected speed during the ON medication state. Kinetic and kinematic gait parameters such as vertical ground reaction force, center of pressure, toe clearance, and FSA were recorded. A Mann-Whitney U test showed a significant increase (p < 0.001) in the toe clearance (within 34% to 64% of the swing phase from the toe-off instance) and FSA, from 87.60 mm and - 5.43degrees respectively during without cue to 94.29 mm and 2.93degrees respectively during with cue walking condition except in one subject. These findings support the potential incorporation of an FSA-based cueing device for toe clearance improvement among PD patients. In addition, the wearable setup supports the cueing device applicability outside laboratory and home settings.

Investigating the Association of Quantitative Gait Stability Metrics With User Perception of Gait Interruption Due to Control Faults During Human-Prosthesis Interaction

This study aims to compare the association of different gait stability metrics with the prosthesis users' perception of their own gait stability. Lack of perceived confidence on the device functionality can influence the gait pattern, level of daily activities, and overall quality of life for individuals with lower limb motor deficits. However, the perception of gait stability is subjective and difficult to acquire online. The quantitative gait stability metrics can be objectively measured and monitored using wearable sensors; however, objective measurements of gait stability associated with human's perception of their own gait stability has rarely been reported. By identifying quantitative measurements that associate with users' perceptions, we can gain a more accurate and comprehensive understanding of an individual's perceived functional outcomes of assistive devices such as prostheses. To achieve our research goal, experiments were conducted to artificially apply internal disturbances in the powered prosthesis while the prosthetic users performed level ground walking. We monitored and compared multiple gait stability metrics and a local measurement to the users' reported perception of their own gait stability. The results showed that the center of pressure progression in the sagittal plane and knee momentum (i.e., residual thigh and prosthesis shank angular momentum about prosthetic knee joint) can potentially estimate the users' perceptions of gait stability when experiencing disturbances. The findings of this study can help improve the development and evaluation of gait stability control algorithms in robotic prosthetic devices.

Provoking Artificial Slips and Trips towards Perturbation-Based Balance Training: A Narrative Review

Humans' balance recovery responses to gait perturbations are negatively impacted with ageing. Slip and trip events, the main causes preceding falls during walking, are likely to produce severe injuries in older adults. While traditional exercise-based interventions produce inconsistent results in reducing patients' fall rates, perturbation-based balance training (PBT) emerges as a promising task-specific solution towards fall prevention. PBT improves patients' reactive stability and fall-resisting skills through the delivery of unexpected balance perturbations. The adopted perturbation conditions play an important role towards PBT's effectiveness and the acquisition of meaningful sensor data for studying human biomechanical reactions to loss of balance (LOB) events. Hence, this narrative review aims to survey the different methods employed in the scientific literature to provoke artificial slips and trips in healthy adults during treadmill and overground walking. For each type of perturbation, a comprehensive analysis was conducted to identify trends regarding the most adopted perturbation methods, gait phase perturbed, gait speed, perturbed leg, and sensor systems used for data collection. The reliable application of artificial perturbations to mimic real-life LOB events may reduce the gap between laboratory and real-life falls and potentially lead to fall-rate reduction among the elderly community.

Multifactorial assessment of older adults able and unable to recover balance during a laboratory-induced trip

BACKGROUND

Older adults are prone to falls, and identifying fallers and non-fallers from a set of fall-related variables is essential while establishing effective preventive programs.

AIMS

This study aimed to analyze if a set of parameters (i.e., strength, functional status, dynamic balance, gait, and obesity-related anthropometric measures) differ between older adults able and unable to recover from an induced trip.

OBJECTIVE

To analyze predictors among older adults able and unable to identify fallers and non-fallers.

METHODS

Thirty healthy old adults were tripped once during the mid-swing phase of the gait. The trip outcome was used as a criterion to assign participants to a recovery (REC; n=21; 71.2±5.7 years; 70.9±12.8 kg; 1.60±0.09 m) or a non-recovery group (NREC; n=9; 69.4±6.8 years; 85.7±11.8 kg; 1.59±0.08 m). The spatiotemporal gait parameters, functional mobility, dynamic balance, and isokinetic muscular function were measured.

RESULTS

The NREC presented larger BMI (33.6±2.7 vs. 27.5±3.4 kg.m-2; p<0.05); greater time for the initiation phase on the voluntary step execution test (197.0±27.9vs. 171.7±31.3s; p<0.05); lower plantarflexor (0.41±0.15 vs. 0.59±0.18 N.m; p<0.05), dorsiflexor (0.18±0.05 vs. 0.24±0.07 N.m; p<0.05), knee extensor (1.03±0.28 vs. 1.33±0.24 N.m; p<0.05) and knee flexor peak torques (0.50±0.15 vs. 0.64±0.13 N.m; p<0.05); and greater time up and go (8.0±0.8 vs. 7.4±0.7s).

CONCLUSIONS

The results showed that it is possible to identify fall risk components based on several fall-related parameters using a laboratory-induced trip as the outcome variable.

Investigating the Effect of Real-Time Center of Pressure (CoP) Feedback Training on the Swing Phase of Lower Limb Kinematics in Transfemoral Prostheses with SACH foot

Transfemoral amputee often encounters reduced toe clearance resulting in trip-related falls. Swing phase joint angles have been shown to influence the toe clearance therefore, training intervention that targets shaping the swing phase joint angles can potentially enhance toe clearance. The focus of this study was to investigate the effect of the shift in the location of the center of pressure (CoP) during heel strike on modulation of the swing phase joint angles in able-bodied participants (n=6) and transfemoral amputees (n=3). We first developed a real-time CoP-based visual feedback system such that participants could shift the CoP during treadmill walking. Next, the kinematic data were collected during two different walking sessions- baseline (without feedback) and feedback (shifting the CoP anteriorly/posteriorly at heel strike to match the target CoP location). Primary swing phase joint angle adaptations were observed with feedback such that during the mid-swing phase, posterior CoP shift feedback significantly increases (p<0.05) the average hip and knee flexion angle by 11.55 degrees and 11.86 degrees respectively in amputees, whereas a significant increase (p<0.05) in ankle dorsiflexion, hip and knee flexion angle by 3.60 degrees, 3.22 degrees, and 1.27 degrees respectively compared to baseline was observed in able-bodied participants. Moreover, an opposite kinematic adaptation was seen during anterior CoP shift feedback. Overall, results confirm a direct correlation between the CoP shift and the modulation in the swing phase lower limb joint angles.

Design and Validation of a Real-Time Visual Feedback System to Improve Minimum Toe Clearance (mTC) in Transfemoral Amputees

Tripping is accompanied by reduced minimum toe clearance (mTC) during the swing phase of gait. The risk of fall due to tripping among transfemoral amputees is nearly 67% which is greater than the transtibial amputees. Therefore, intervention to improve mTC can potentially enhance the quality of life among transfemoral amputees. In this paper, we first develop a real-time visual feedback system with center of pressure (CoP) information. Next, we recruited six non-disabled and three transfemoral amputees to investigate the effect on mTC while participants were trained to shift the CoP anteriorly/posteriorly during heel strike. Finally, to assess the lasting effect of training on mTC, retention trials were conducted without feedback. During feedback, posterior shift in the CoP improved the mTC significantly from 4.68 ± 0.40 cm to 6.12 ± 0.68 cm (p < 0.025) in non-disabled participants. A similar significant improvement in mTC from 4.60 ± 0.55 cm to 5.62 ± 0.57 cm was observed in amputees during posterior shift of CoP. Besides mTC, maximal toe clearances, i.e., maxTC₁ and maxTC₂, also showed a significant increase (p < 0.025) during the posterior shift of CoP in both the participants. Moreover, during retention, mTC did not differ significantly (p > 0.05) from feedback condition in amputee, suggesting a positive effect of feedback training. The foot-to-ground angle (FGA) at mTC increased significantly (p < 0.025) during posterior shift feedback in non-disabled suggests active ankle dorsiflexion in increasing mTC. However, in amputees, FGA at mTC did not differ significantly during both anterior and posterior CoP shift feedback. The present findings suggest CoP feedback as a potential strategy during gait rehabilitation of transfemoral amputees.

Stepping to an Auditory Metronome Improves Weight-Bearing Symmetry in Poststroke Hemiparesis

Asymmetry in weight-bearing is a common feature in poststroke hemiparesis and is related to temporal asymmetry during walking. The aim of this study was to investigate the effect of an auditory cue for stepping in place on measures of temporal and weight-bearing asymmetry. A total of 10 community-dwelling adults (6 males and 4 females) with chronic poststroke hemiparesis performed 5 un-cued stepping trials and 5 stepping trials cued by an auditory metronome cue. A Vicon system was used to collect full body kinematic trajectories. Two force platforms were used to measure ground reaction forces. Step, swing, and stance times were used to calculate temporal symmetry ratios. Weight-bearing was assessed using the vertical component of the ground reaction force and center of mass-center of pressure separation at mid-stance. Weight-bearing asymmetry was significantly reduced during stepping with an auditory cue. Asymmetry values for step, swing, and stance times were also significantly reduced with auditory cueing. These findings show that auditory cueing when stepping in place produces immediate reductions in measures of temporal asymmetry and dynamic weight-bearing asymmetry.

Quantifying Dynamic Balance in Young, Elderly and Parkinson's Individuals: A Systematic Review

Introduction: Falling is one of the primary concerns for people with Parkinson's Disease and occurs predominately during dynamic movements, such as walking. Several methods have been proposed to quantify dynamic balance and to assess fall risk. However, no consensus has been reached concerning which method is most appropriate for examining walking balance during unperturbed and perturbed conditions, particularly in Parkinson's Disease individuals. Therefore, this systematic review aimed to assess the current literature on quantifying dynamic balance in healthy young, elderly and Parkinson's individuals during unperturbed and perturbed walking. Methods: The PubMed database was searched by title and abstract for publications quantifying dynamic balance during unperturbed and mechanically perturbed walking conditions in elderly adults and PD. Inclusion criteria required publications to be published in English, be available in full-text, and implement a dynamic balance quantification method. Exclusion criteria included clinical dynamic balance measures, non-mechanical perturbations, pathologies other than PD, and dual-tasking conditions. The initial database search yielded 280 articles, however, only 81 articles were included after title, abstract and full-text screening. Methodological quality and data were extracted from publications included in the final synthesis. Results: The dynamic balance articles included 26 Coefficient of Variation of Spatiotemporal Variability, 10 Detrended Fluctuation Analysis, 20 Lyapunov Exponent, 7 Maximum Floquet Multipliers, 17 Extrapolated Center of Mass, 11 Harmonic Ratios, 4 Center of Mass-Center of Pressure Separation, 2 Gait Stability Ratio, 1 Entropy, 3 Spatiotemporal Variables, 2 Center of Gravity and Center of Pressure, and 2 Root Mean Square in the final synthesis. Assessment of methodological quality determined that 58 articles had a low methodological rating, a 22 moderate rating, and 1 having a high rating. Conclusion: Careful consideration must be given when selecting a method to quantify dynamic balance because each method defines balance differently, reflects a unique aspect of neuromuscular stability mechanisms, and is dependent on the walking condition (unperturbed vs. perturbed). Therefore, each method provides distinct information into stability impairment in elderly and PD individuals.

Ankle Proprioception-Associated Gait Patterns in Older Adults: Results from the Baltimore Longitudinal Study of Aging

INTRODUCTION

Ankle proprioception training has been found to improve balance-related gait disorders; however, the relationship between ankle proprioception and specific gait patterns in older adults with and without impaired balance has not been systematically examined.

METHODS

This study characterizes gait patterns of 230 older adults age 60-95 yr evaluated in the Baltimore Longitudinal Study of Aging gait laboratory with (n = 82) and without impaired balance (inability to successfully complete a narrow walk) and examines ankle proprioception performance.

RESULTS

Participants with impaired balance had a higher angle threshold for perceiving ankle movement than those without impaired balance even after controlling for the substantial age difference between groups (P = 0.017). Gait speed, stride length, hip and ankle range of motion, and mechanical work expenditure from the knee and ankle were associated with ankle proprioception performance (P < 0.050 for all) in the full sample, but these associations were evident only in participants with impaired balance in stratified analysis.

CONCLUSION

Ankle proprioception in older persons with balance impairment may play a role in balance-related gait disorders and should be targeted for intervention.

Focusing on heel strike improves toe clearance in people with Parkinson's disease: an observational pilot study

OBJECTIVES

To investigate differences in toe clearance between people with PD and age-matched healthy elderly (HE) during comfortable walking and to study the effects of dual-tasking and the use of an attentional strategy emphasizing heel strike on toe clearance.

DESIGN

Observational cross-sectional study.

SETTING

Camera-based 3D gait laboratory.

PARTICIPANTS

Ten persons with PD (Hoehn and Yahr I to III) having mild gait disturbances and 10 HE.

INTERVENTIONS

Participants walked for two minutes under three conditions at comfortable pace: single-task walking, attending to heel strike during single-task walking, and dual-task walking.

MAIN OUTCOME MEASURES

Minimal and maximal toe clearance; foot strike angle with the ground.

RESULTS

People with PD had less maximal toe clearance in the end of the swing phase and a smaller foot strike angle than HE during all three walking conditions. Impairments significantly diminished during heel strike focused walking improving performance to equal the HE. Heel strike focused walking resulted in an increased minimal toe clearance and a longer duration of end swing phase when compared to walking with and without a dual-task. The attentional strategy to focus on heel strike improved the stride length when compared to dual-task walking. Surprisingly, minimal toe clearance did not differ between PD and HE in any of the conditions and there were no dual-task effects on toe clearance.

CONCLUSION

These findings provide evidence favoring the potential incorporation of an attentional strategy focusing on the heel strike in PD gait rehabilitation.

Tripping Elicits Earlier and Larger Deviations in Linear Head Acceleration Compared to Slipping

Slipping and tripping contribute to a large number of falls and fall-related injuries. While the vestibular system is known to contribute to balance and fall prevention, it is unclear whether it contributes to detecting slip or trip onset. Therefore, the purpose of this study was to investigate the effects of slipping and tripping on head acceleration during walking. This information would help determine whether individuals with vestibular dysfunction are likely to be at a greater risk of falls due to slipping or tripping, and would inform the potential development of assistive devices providing augmented sensory feedback for vestibular dysfunction. Twelve young men were exposed to an unexpected slip or trip. Head acceleration was measured and transformed to an approximate location of the vestibular system. Peak linear acceleration in anterior, posterior, rightward, leftward, superior, and inferior directions were compared between slipping, tripping, and walking. Compared to walking, peak accelerations were up to 4.68 m/s2 higher after slipping, and up to 10.64 m/s2 higher after tripping. Head acceleration first deviated from walking 100-150ms after slip onset and 0-50ms after trip onset. The temporal characteristics of head acceleration support a possible contribution of the vestibular system to detecting trip onset, but not slip onset. Head acceleration after slipping and tripping also appeared to be sufficiently large to contribute to the balance recovery response.