Using dynamic walking models to identify factors that contribute to increased risk of falling in older adults

Balance recovery after trips is affected by the type of tripping obstacles

Occupational falls are often initiated by trips. Mechanical perturbations applied onto the tripped foot are different for different types of tripping obstacles. The present study aimed to determine how different types of tripping obstacles affect balance recovery after trips. Sixty-four healthy adults participated in an experimental study. They were instructed to perform several walking trials, during which two trips were randomly induced, one by a pole-like obstacle and the other by a board-like obstacle. Balance recovery after trips was measured and compared between the two obstacles. Results showed that the board-like obstacle led to longer step-off time, shorter recovery step duration, and smaller minimum hip height, suggesting that the risk of trip-initiated falls could be higher with the board-like obstacle vs. the pole-like obstacle. This finding presents the need for future research to consider the influence of obstacle type when exploring mechanisms for trips and falls.

Visual Illusion Created by a Striped Pattern Through Augmented Reality for the Prevention of Tumbling on Stairs

A fall on stairs can be a dangerous accident. An important indicator of falling risk is the foot clearance, which is the height of the foot when ascending stairs or the distance of the foot from the step when descending. We developed an augmented reality system with a holographic lens using a visual illusion to improve the foot clearance on stairs. The system draws a vertical striped pattern on the stair riser as the participant ascends the stairs to create the illusion that the steps are higher than the actual steps, and draws a horizontal striped pattern on the stair tread as the participant descends the stairs to create the illusion of narrower stairs. We experimentally evaluated the accuracy of the system and fitted a model to determine the appropriate stripe thickness. Finally, participants ascended and descended stairs before, during, and after using the augmented reality system. The foot clearance significantly improved, not only while the participants used the system but also after they used the system compared with before.

Identifying sensors-based parameters associated with fall risk in community-dwelling older adults: an investigation and interpretation of discriminatory parameters

BACKGROUND

Falls pose a severe threat to the health of older adults worldwide. Determining gait and kinematic parameters that are related to an increased risk of falls is essential for developing effective intervention and fall prevention strategies. This study aimed to investigate the discriminatory parameter, which lay an important basis for developing effective clinical screening tools for identifying high-fall-risk older adults.

METHODS

Forty-one individuals aged 65 years and above living in the community participated in this study. The older adults were classified as high-fall-risk and low-fall-risk individuals based on their BBS scores. The participants wore an inertial measurement unit (IMU) while conducting the Timed Up and Go (TUG) test. Simultaneously, a depth camera acquired images of the participants' movements during the experiment. After segmenting the data according to subtasks, 142 parameters were extracted from the sensor-based data. A t-test or Mann-Whitney U test was performed on the parameters for distinguishing older adults at high risk of falling. The logistic regression was used to further quantify the role of different parameters in identifying high-fall-risk individuals. Furthermore, we conducted an ablation experiment to explore the complementary information offered by the two sensors.

RESULTS

Fifteen participants were defined as high-fall-risk individuals, while twenty-six were defined as low-fall-risk individuals. 17 parameters were tested for significance with p-values less than 0.05. Some of these parameters, such as the usage of walking assistance, maximum angular velocity around the yaw axis during turn-to-sit, and step length, exhibit the greatest discriminatory abilities in identifying high-fall-risk individuals. Additionally, combining features from both devices for fall risk assessment resulted in a higher AUC of 0.882 compared to using each device separately.

CONCLUSIONS

Utilizing different types of sensors can offer more comprehensive information. Interpreting parameters to physiology provides deeper insights into the identification of high-fall-risk individuals. High-fall-risk individuals typically exhibited a cautious gait, such as larger step width and shorter step length during walking. Besides, we identified some abnormal gait patterns of high-fall-risk individuals compared to low-fall-risk individuals, such as less knee flexion and a tendency to tilt the pelvis forward during turning.

Differences in Balance Confidence, Fear of Falling, and Fall Risk Factors Among White and Black Community-Dwelling Older Adults

BACKGROUND AND PURPOSE

Falling among older adults is common and can cause chronic health complications. Fear of falling, a lasting concern about falling that can lead an individual to avoid activities he or she can perform, is strongly associated with falling and fall risk. Although White older adults fall more often, Black older adults have more fall risk factors. The purpose of this study was to investigate factors that explain fear of falling and differences between White and Black community-dwelling older adults in fear of falling, balance confidence, and fall risk factors.

METHODS

Using a cross-sectional, retrospective design, 84 community-dwelling older adults (mean age [SD] = 69.0 [5.2], range: 55-80; White, n = 37, 44%; Black, n = 47, 56%, M/F = 20/64) were assessed. Assessments were conducted in a laboratory for human studies. Fall history and risk factors, and subjective fear of falling, were collected. The Montreal Cognitive Assessment (MoCA), Activities-Specific Balance Confidence (ABC) score, preferred, backward, and fast Gait Speed, Short Form-12 Physical and Mental Component Scores, fear of falling rating scale, and demographics questionnaires were administered. Analyses included a proportional odds logistic regression model to examine which factors predicted ABC score and which factors were associated with subjective fear of falling, 1-way analysis of variance for continuous variables, the Fisher exact test for categorical variables, and the Mann-Whitney-Wilcoxon test for ordinal variables.

RESULTS

Black participants had significantly fewer years of education ( P = .007), lower MoCA scores ( P = .002), and slower fast gait speed ( P = .032) than White participants. Black participants reported less subjective fear of falling ( P = .043). In the final ABC model (Akaike information criterion 208.26), lower ABC scores were predicted by White race, slower preferred and fast gait speeds, and worse Short Form-12 Mental Composite Scores.

DISCUSSION

Despite Black participants demonstrating typical characteristics of higher fall risk including lower cognitive scores, slower gait speed, and lower ABC scores, Black participants reported fewer falls. Understanding racial differences is an important factor in fear of falling and balance confidence.

CONCLUSION

Reasons for racial differences should be examined further in fear of falling and balance confidence to facilitate the development of patient-centered falls prevention physical therapy programs.

Age-Related Differences in Intermuscular Coherence EMG-EMG of Ankle Joint Antagonist Muscle Activity during Maximal Leaning

BACKGROUND

Intermuscular synchronization is one of the fundamental aspects of maintaining a stable posture and is of great importance in the aging process. This study aimed to assess muscle synchronization and postural stabilizer asymmetry during quiet standing and the limits of stability using wavelet analysis. Intermuscular synchrony and antagonistic sEMG-sEMG (surface electromyography) coherence asymmetry were evaluated in the tibialis anterior and soleus muscles.

METHODS

The study involved 20 elderly (aged 65 ± 3.6) and 20 young (aged 21 ± 1.3) subjects. The task was to perform a maximum forward bend in a standing position. The prone test was divided into three phases: quiet standing (10 s), dynamic learning, and maintenance of maximum leaning (20 s). Wavelet analysis of coherence was performed in the delta and beta bands.

RESULTS

Young subjects modulated interface coherences to a greater extent in the beta band. Analysis of postural stability during standing tasks showed that only the parameter R2b (the distance between the maximal and minimal position central of pressure), as an indicator for assessing the practical limits of stability, was found to be significantly associated with differences in aging.

CONCLUSION

The results showed differences in the beta and delta band oscillations between young and older subjects in a postural task involving standing quietly and leaning forward.

Acute effect of traditional and adaptive metronomes on gait variability in older individuals with a history of falls

BACKGROUND

Metronome cueing has been shown to reduce gait variability and thereby potentially reduce falls risk in individuals with Parkinson's disease. It is unclear however, if metronome cueing has a similar effect in healthy older adults with a history of falls.

AIM

To investigate whether a traditional and/or an adaptive metronome, based on an individual's gait pattern, were effective in reducing gait variability in older adults with a history of falls.

METHODS

Twenty older adults (15 women, 71 ± 4.9 years) with a history of falls were included in this cross-over study. Participants received two types of cueing (adaptive and traditional metronome) 1 week apart. The variability of the participants' stride time, stride length, walking speed and duration of double leg support were recorded during three walking conditions (baseline, during feedback and post-feedback gait). Repeated-measures ANOVA was used to assess the possible effects of the two cueing strategies on gait variables.

RESULTS

Compared with the baseline condition, participants had significantly increased stride time variability during feedback (F (2) = 9.83, p < 0.001) and decreased double leg support time variability post-feedback (F (2) 3.69, p = 0.034). Increased stride time variability was observed with the adaptive metronome in comparison to the traditional metronome.

CONCLUSION

Metronome cueing strategies may reduce double leg support variability in older adults with a history of falls but seem to increase stride time variability. Further studies are needed to investigate if metronome cueing is more beneficial for individuals with greater baseline gait variability than those included in the current study.

Age-related changes to vestibular heave and pitch perception and associations with postural control

Falls are a common cause of injury in older adults (OAs), and age-related declines across the sensory systems are associated with increased falls risk. The vestibular system is particularly important for maintaining balance and supporting safe mobility, and aging has been associated with declines in vestibular end-organ functioning. However, few studies have examined potential age-related differences in vestibular perceptual sensitivities or their association with postural stability. Here we used an adaptive-staircase procedure to measure detection and discrimination thresholds in 19 healthy OAs and 18 healthy younger adults (YAs), by presenting participants with passive heave (linear up-and-down translations) and pitch (forward-backward tilt rotations) movements on a motion-platform in the dark. We also examined participants' postural stability under various standing-balance conditions. Associations among these postural measures and vestibular perceptual thresholds were further examined. Ultimately, OAs showed larger heave and pitch detection thresholds compared to YAs, and larger perceptual thresholds were associated with greater postural sway, but only in OAs. Overall, these results suggest that vestibular perceptual sensitivity declines with older age and that such declines are associated with poorer postural stability. Future studies could consider the potential applicability of these results in the development of screening tools for falls prevention in OAs.

Vestibular Perceptual Thresholds in Older Adults With and Without Age-related Hearing Loss

OBJECTIVES

Older adults with age-related hearing loss (ARHL) are at greater risk of falling and have greater mobility problems than older adults with normal hearing (NH). The underlying cause of these associations remains unclear. One possible reason is that age-related declines in the vestibular system could parallel those observed in the auditory system within the same individuals. Here, we compare the sensitivity of vestibular perceptual abilities (psychophysics), vestibular end-organ functioning (vestibular evoked myogenic potentials and video head impulse tests), and standing balance (posturography) in healthy older adults with and without ARHL.

DESIGN

A total of 46 community-dwelling older adults, 23 with ARHL and 23 with NH, were passively translated in heave (up and down) and rotated in pitch (tilted forward and backward) in the dark using a motion platform. Using an adaptive staircase psychophysical procedure, participants' heave and pitch detection and discrimination thresholds were determined. In a posturography task, participants' center of pressure (COP) path length was measured as they stood on a forceplate with eyes open and closed, on firm and compliant surfaces, with and without sound suppression. Baseline motor, cognitive, and sensory functioning, including vestibular end-organ function, were measured.

RESULTS

Individuals with ARHL were less sensitive at discriminating pitch movements compared to older adults with NH. Poorer self-reported hearing abilities were also associated with poorer pitch discrimination. In addition to pitch discrimination thresholds, lower pitch detection thresholds were significantly associated with hearing loss in the low-frequency range. Less stable standing balance was significantly associated with poorer vestibular perceptual sensitivity.

DISCUSSION

These findings provide evidence for an association between ARHL and reduced vestibular perceptual sensitivity.

A progressive-individualized midstance gait perturbation protocol for reactive balance assessment in stroke survivors

Restoration of balance control is a primary focus of rehabilitation after a stroke. The study developed a gait perturbation, treadmill-based, balance assessment protocol and demonstrated that it can be used to quantify improvements in reactive balance responses among individuals post-stroke. The protocol consists of a sequence of fifteen 90-second treadmill walking trials, with a single perturbation applied during the middle third of each trial. Gait was perturbed by rapid acceleration-deceleration of the treadmill belt at mid-stance of the unaffected leg during a randomly selected gait cycle. The initial perturbation magnitude was based on the participant's maximum walking speed and increased or decreased in each trial, based on success or failure of recovery, as determined from an instrumented harness. The protocol was used before and after a 10-week period of therapy in twenty-four stroke survivors. Outcomes included maximum recoverable perturbation (MRP), self-selected gait speed, levels progressed through the algorithm, and falls versus recoveries.Participants were able to take recovery steps in response to the perturbation. Twelve participants completed the full assessment protocol before and after the therapeutic intervention. After the intervention, they had fewer falls and more recoveries (p < 0.001), progressed through more algorithm levels (p = 0.043), had a higher MRP (p = 0.005), and had higher gait speeds. The protocol was found to be feasible in stroke survivors with moderate gait deficits. The data supports the conclusion that this protocol can be used in clinical research to quantify improvements in balance during walking.

Gait Parameters of Older Adults according to Their Fall History and Functional Capacity While Walking at Different Speeds

INTRODUCTION

It is believed that functional capacity and fall history are factors capable of influencing the gait parameters of older adults. Thus, the objective of this study was to verify whether gait parameters of community-dwelling older adults differ according to their functional capacity and fall history when walking at self-selected walking speed (SSWS) and fast walking speed (FWS) using principal component analysis (PCA).

METHODS

Two hundred ninety-five participants (82.3% women and 17.7% men) were allocated in four groups according to their fall history and functional capacity: non-fallers with higher functional capacity (NFHFC, n = 94; 69.3 ± 5.5 years), non-fallers with lower functional capacity (NFLFC, n = 114; 72.0 ± 8.1 years), fallers with higher functional capacity (FHFC, n = 29; 70.0 ± 6.0 years), and fallers with lower functional capacity (FLFC, n = 58; 72.5 ± 8.2 years). Fall history, anthropometric data, functional capacity by short physical performance battery and mobility by Timed Up and Go (TUG), and spatiotemporal gait parameters were evaluated.

RESULTS

Data analysis indicated that FLFC presented the lowest scores, especially in the Five Times Sit-to-Stand Test and TUG. The PCA showed that the first principal component (PC1) explained the most substantial amount of the data variability in both walking speeds (SSWS and FWS), predominantly including temporal parameters. PC2 composed by spatial outcomes (stride and step length and walking speed) showed the highest effect size. PC1 and PC2 were able to differentiate functional status, regardless of fall history.

CONCLUSIONS

Functional capacity showed great importance when analyzing gait parameters at different walking speeds (SSWS and FWS), regardless of fall history. Older adults with high functional capacity demonstrate better performance during gait. Besides, spatiotemporal parameters are the main factors explaining gait variability, both in SSWS and FWS.

Soft tissue vibration: a biologically-inspired mechanism for stabilizing bipedal locomotion

Humans are made up of mostly soft tissue that vibrates during locomotion. This vibration has been shown to store and dissipate energy during locomotion. However, the effects of soft tissue vibration (wobbling masses) on the dynamics of bipedal walking have not been assessed in terms of stability. Given that much of the human body is vibrating just following foot-ground contact, it may have dynamic implications on the stability of walking. A rigid bipedal walker and a bipedal walker with soft tissue were simulated to quantify the effects of soft tissue vibration on gait periodicity, orbital stability, global stability, and robustness to uneven terrain. It was found that moderate amounts of energy dissipation resulted in much more stable walking dynamics relative to that of a rigid bipedal walker.

Effect of simulated sensorimotor noise on kinematic variability and stability of a biped walking model

Whether higher variability in older adults' walking is an indication of increased instability has been challenged recently. We performed a computer simulation to investigate the effect of sensorimotor noise on the kinematic variability and stability in a biped walking model. Stochastic differential equations of the system with additive Gaussian white noise was constructed and solved. Sensorimotor noise mainly resulted in higher kinematic variability but its influence on gait stability is minimal. This implies that kinematic variability evident in walking gaits of older adults could be the result of internal sensorimotor noise and not an indication of instability.

Less Is More - Estimation of the Number of Strides Required to Assess Gait Variability in Spatially Confined Settings

Background: Gait variability is an established marker of gait function that can be assessed using sensor-based approaches. In clinical settings, spatial constraints and patient condition impede the execution of longer distance walks for the recording of gait parameters. Turning paradigms are often used to overcome these constraints and commercial gait analysis systems algorithmically exclude turns for gait parameters calculations. We investigated the effect of turns in sensor-based assessment of gait variability.

Methods: Continuous recordings from 31 patients with movement disorders (ataxia, essential tremor and Parkinson’s disease) and 162 healthy elderly (HE) performing level walks including 180° turns were obtained using an inertial sensor system. Accuracy of the manufacturer’s algorithm of turn-detection was verified by plotting stride time series. Strides before and after turn events were extracted and compared to respective average of all strides. Coefficient of variation (CoV) of stride length and stride time was calculated for entire set of strides, segments between turns and as cumulative values. Their variance and congruency was used to estimate the number of strides required to reliably assess the magnitude of stride variability.

Results: Non-detection of turns in 5.8% of HE lead to falsely increased CoV for these individuals. Even after exclusion of these, strides before/after turns tended to be spatially shorter and temporally longer in all groups, contributing to an increase of CoV at group level and widening of confidence margins with increasing numbers of strides. This could be attenuated by a more generous turn excision as an alternative approach. Correlation analyses revealed excellent consistency for CoVs after at most 20 strides in all groups. Respective stride counts were even lower in patients using a more generous turn excision.

Conclusion: Including turns to increase continuous walking distance in spatially confined settings does not necessarily improve the validity and reliability of gait variability measures. Specifically with gait pathology, perturbations of stride characteristics before/after algorithmically excised turns were observed that may increase gait variability with this paradigm. We conclude that shorter distance walks of around 15 strides suffice for reliable and valid recordings of gait variability in the groups studied here.

Ground reaction forces intersect above the center of mass even when walking down visible and camouflaged curbs

A main objective in bipedal walking is controlling the whole body to stay upright. One strategy that promotes this objective is to direct the ground reaction forces (GRF) to a point above the center of mass (COM). In humans such force patterns can be observed for unperturbed walking, but it is not known if the same strategy is used when humans walk across a change in walkway height. In this study, eleven volunteers stepped down off a visible (0, 10, and 20 cm) and a camouflaged (0 or 10 cm) curb while walking at two different speeds (1.2±0.1 m s−1 and 1.7±0.1 m s−1). The results showed that in all conditions the GRF pointed predominantly above the COM. Vectors directed from the center of pressure (COP) to the intersection point (IP) closely fitted the measured GRF direction not only in visible conditions (R2&gt;97.5%), but also in camouflaged curb negotiation (R2&gt;89.8%). Additional analysis of variables included in the calculation of the IP location showed considerable differences for the camouflaged curb negotiation: Compared to level walking, the COP shifted posterior relative to the COM and the vertical GRF were higher in the beginning and lower in later parts of the stance phase of the perturbed contact. The results suggest that IP behavior can be observed for both visible and camouflaged curb negotiation. For further regulation of the whole body angle the asymmetrical vertical GRF could counteract the effect of a posterior shifted step.

Feasibility of Automated Mobility Assessment of Older Adults via an Instrumented Cane

This study explored the feasibility of automated characterization of functional mobility via an Instrumented Cane System (ICS) within an older adult sample of cane users. An off-the-shelf offset cane was instrumented with inertial, force, and ultrasound sensors for noninvasive data collection. Eighteen patients from a neurological out-patient rehabilitation clinic and nine independently mobile controls participated in standard clinical evaluations of mobility using the ICS while under the care of an attending physical therapist. Feasibility of the ICS was gauged through two studies. The first demonstrated the capability of the ICS to reliably collect meaningful usage metrics, and the second provided preliminary support for the discriminability of high and low falls risk from system-reported metrics. Specifically, the cane significantly differentiated patients and controls (p < 0.05), and a measure of the variation in rotational velocity was associated with total scores on the Functional Gait Assessment (partial r = 0.61, p < 0.01). These findings may ultimately serve to complement and even extend current clinical assessment practices.

The motor repertoire of older adult fallers may constrain their response to balance perturbations

Older adults are at a high risk of falls, and most falls occur during locomotor activities like walking. This study aimed to improve our understanding of changes in neuromuscular control associated with increased risk of falls in older adults in the presence of dynamic balance challenges during walking. Motor module (also known as muscle synergy) analyses identified changes in the neuromuscular recruitment of leg muscles during walking with and without perturbations designed to elicit the visual perception of lateral instability. During normal walking we found that a history of falls (but not age) was associated with reduced motor module complexity and that age (but not a history of falls) was associated with increased step-to-step variability of module recruitment timing. Furthermore, motor module complexity was unaltered in the presence of optical flow perturbations. The specific effects of a history of falls on leg muscle recruitment included an absence and/or inability to independently recruit motor modules normally recruited to perform biomechanical functions important for walking balance control. These results suggest that fallers do not recruit the appropriate motor modules necessary for well-coordinated walking balance control even in the presence of perturbations. The identified changes in the modular control of walking balance in older fallers may either represent a neural deficit that leads to poor balance control or a prior history of falls that results in a compensatory motor adaptation. In either case, our study provides initial evidence that a reduced motor repertoire in older adult fallers may be a constraint on their ability to appropriately respond to balance challenges during walking. NEW & NOTEWORTHY This is the first study to demonstrate a reduced motor repertoire during walking in older adults with a history of falls but without any overt neurological deficits. Furthermore, using virtual reality during walking to elicit the visual perception of lateral instability, we provide initial evidence that a reduced motor repertoire in older adult fallers may be a constraint on their ability to appropriately respond to balance challenges during walking.

Relationship between the FRAX® score and falls in community-dwelling middle-aged and elderly people

OBJECTIVES

Falls is a risk factor for fracture. The FRAX^® predicts fractures. Whether the FRAX^® is associated with fall in both gender is inconclusive. The aim of our study is to evaluate the association between FRAX scores and falls.

METHODS

The cross-sectional study set from 2009 to 2010 included 1200 community-dwelling people who were systematically sampled in central Taiwan. The 1200 participants (men: 524; women: 676; ≥40 years old) completed questionnaires about socioeconomic status; lifestyle; medical and fall history were completed. FRAX scores with and without bone mineral density (BMD) were calculated by using the Taiwan calculator.

RESULTS

A total of 19.8% participants fell down. Binary regression models showed that diabetes mellitus history (OR: 1.61; 95% CI: 1.03-2.52), the FRAX without BMD in a continuous major score (OR: 1.06; 95% CI: 1.03-1.09), continuous hip score (OR: 1.11; 95% CI: 1.05-1.16), categorical major score ≥ 10% (OR: 1.81; 95% CI: 1.25-2.61), and categorical hip score ≥ 3% (OR: 1.80; 95% CI: 1.30-2.50) were independent risk factors for falls. FRAX with BMD in a continuous major score (OR: 1.04; 95% CI: 1.02-1.06), continuous hip score (OR: 1.06; 95% CI: 1.02-1.09), categorical major score ≥ 10% (OR: 1.52; 95% CI: 1.09-2.12), and categorical hip score ≥ 3% (OR: 1.53; 95% CI: 1.13-2.09) were also independent risk factors.

CONCLUSIONS

We concluded that FRAX^® scores with and without BMD were unanimously correlated with falls in community-dwelling middle-aged and elderly males and females.

Visual, Musculoskeletal, and Balance Complaints in AMD: A Follow-Up Study

Purpose. To investigate whether patients with age-related macular degeneration (AMD) run a potentially higher risk of developing visual, musculoskeletal, and balance complaints than age-matched controls with normal vision. Methods. Visual assessments, self-rated visual function, self-rated visual, musculoskeletal, and balance complaints, and perceived general health were obtained in 37 AMD patients and 18 controls, at baseline and after an average of 3.8 years later. Results. At follow-up both groups reported decreased visual acuity (VA) and visual function, but only AMD patients reported significantly increased visual, musculoskeletal, and balance complaints. Decreased VA, need for larger font size when reading, need for larger magnification, and decreased self-rated visual function were identified as risk markers for increased complaints in AMD patients. These complaints were also identified as risk markers for decreased health. For controls, decreased VA and self-reported visual function were associated with increased visual and balance complaints. Conclusions. Visual deterioration was a risk marker for increased visual, musculoskeletal, balance, and health complaints in AMD patients. Specifically, magnifying visual aids, such as CCTV, were a risk marker for increased complaints in AMD patients. This calls for early and coordinated actions to treat and prevent visual, musculoskeletal, balance, and health complaints in AMD patients.

Gait Efficiency on an Uneven Surface Is Associated with Falls and Injury in Older Subjects with a Spectrum of Lower Limb Neuromuscular Function: A Prospective Study

OBJECTIVE

The objective of this study was to determine which gait measures on smooth and uneven surfaces predict falls and fall-related injuries in older subjects with diabetic peripheral neuropathy.

DESIGN

Twenty-seven subjects (12 women) with a spectrum of peripheral nerve function ranging from normal to moderately severe diabetic peripheral neuropathy walked on smooth and uneven surfaces, with gait parameters determined by optoelectronic kinematic techniques. Falls and injuries were then determined prospectively over the following year.

RESULTS

Seventeen subjects (62.9%) fell and 12 (44.4%) sustained a fall-related injury. As compared with nonfallers, the subject group reporting any fall, as well as the subject group reporting fall-related injury, demonstrated decreased speed, greater step width (SW), shorter step length (SL), and greater SW-to-SL ratio (SW:SL) on both surfaces. Uneven surface SW:SL was the strongest predictor of falls (pseudo-r = 0.65; P = 0.012) and remained so with inclusion of other relevant variables into the model. Post hoc analysis comparing injured with noninjured fallers showed no difference in any gait parameter.

CONCLUSION

SW:SL on an uneven surface is the strongest predictor of falls and injuries in older subjects with a spectrum of peripheral neurologic function. Given the relationship between SW:SL and efficiency, older neuropathic patients at increased fall risk appear to sacrifice efficiency for stability on uneven surfaces.

Effect of flip-flops on lower limb kinematics during walking: a cross-sectional study using three-dimensional gait analysis

BACKGROUND

Flip-flops are a popular footwear choice in warm weather however their minimalist design offers little support to the foot.

AIM

To investigate the effect of flip-flops on lower limb gait kinematics in healthy adults, to measure adherence between the flip-flop and foot, and to assess the effect on toe clearance in swing.

METHODS

Fifteen healthy adults (8 male, mean age 27 years) completed a three-dimensional gait analysis assessment using Codamotion. Kinematic and lower limb temporal-spatial data were captured using the Modified Helen Hayes marker set with additional markers on the hallux and flip-flop sole.

RESULTS

Compared to barefoot walking, there were no differences in temporal-spatial parameters walking with flip-flops. There was an increase in peak knee flexion in swing (mean difference 4.6°, 95 % confidence interval (CI) [-5.8°, -3.4°], p < 0.001) and peak ankle dorsiflexion at terminal swing (mean difference 2°, 95 % CI [-3°, -1°], p = 0.001). Other kinematic parameters were unchanged. Peak separation between foot and flip-flop was 8.8 cm (SD 1.48), occurring at pre-swing. Minimum toe clearance of the hallux in barefoot walking measured 4.2 cm (SD 0.8). Minimum clearance of the flip-flop was 1.6 cm (SD 0.56).

CONCLUSIONS

Healthy adults adapted well to flip-flops. However, separation of the flip-flop from the foot led to increased knee flexion and ankle dorsiflexion in swing, probably to ensure that the flip-flop did not contact the ground and to maximise adherence to the foot. Minimum clearance of the flip-flop was low compared to barefoot clearance. This may increase the risk of tripping over uneven ground.

FOOT LOADING PATTERNS WITH DIFFERENT UNSTABLE SOLES STRUCTURE

Foot loading patterns can be changed by using different unstable sole structures, detailed quantification of which is of great significance for research and technological development in falling prevention and lower limb disorders rehabilitation. In this study, unstable soles constructions are adjusted through unstable elements in heel and medial, neutral and lateral forefoot and the foot loading patterns are comparatively studied. A total of 22 healthy male subjects participated in this test. Subjects are asked to walk over a 12 m walkway with control shoes and experimental shoes in self-adapted speed. Significant peak pressure, contact area and pressure-time integral differences in middle foot are found between control shoes and experimental shoes. In addition, peak pressure and pressure-time integral are found to increase significantly with unstable elements adding to center forefoot. The results showed that adjusting the unstable elements in coronal plane of forefoot could effectively alter the distribution of plantar pressure, this could potentially offer a mechanism for preventing falling of elderly and rehabilitation of lower extremity malfunctions. This study also demonstrates a novel concept that unstable element could be effectively adjusted in terms of position to meet different functional requirement.