Elderly fall risk prediction using static posturography

A Postural Assessment Utilizing Machine Learning Prospectively Identifies Older Adults at a High Risk of Falling

Introduction: Falls are the leading cause of accidental death in older adults. Each year, 28.7% of US adults over 65 years experience a fall resulting in over 300,000 hip fractures and $50 billion in medical costs. Annual fall risk assessments have become part of the standard care plan for older adults. However, the effectiveness of these assessments in identifying at-risk individuals remains limited. This study characterizes the performance of a commercially available, automated method, for assessing fall risk using machine learning.

Methods: Participants (N = 209) were recruited from eight senior living facilities and from adults living in the community (five local community centers in Houston, TX) to participate in a 12-month retrospective and a 12-month prospective cohort study. Upon enrollment, each participant stood for 60 s, with eyes open, on a commercial balance measurement platform which uses force-plate technology to capture center-of-pressure (60 Hz frequency). Linear and non-linear components of the center-of-pressure were analyzed using a machine-learning algorithm resulting in a postural stability (PS) score (range 1–10). A higher PS score indicated greater stability. Participants were contacted monthly for a year to track fall events and determine fall circumstances. Reliability among repeated trials, past and future fall prediction, as well as survival analyses, were assessed.

Results: Measurement reliability was found to be high (ICC(2,1) [95% CI]=0.78 [0.76–0.81]). Individuals in the high-risk range (1-3) were three times more likely to fall within a year than those in low-risk (7–10). They were also an order of magnitude more likely (12/104 vs. 1/105) to suffer a spontaneous fall i.e., a fall where no cause was self-reported. Survival analyses suggests a fall event within 9 months (median) for high risk individuals.

Conclusions: We demonstrate that an easy-to-use, automated method for assessing fall risk can reliably predict falls a year in advance. Objective identification of at-risk patients will aid clinicians in providing individualized fall prevention care.

Fall-related functional impairments in patients with neurological gait disorder

Falls are common in patients with neurological disorders and are a primary cause of injuries. Nonetheless, fall-associated gait characteristics are poorly understood in these patients. Objective, quantitative gait analysis is an important tool to identify the principal fall-related motor characteristics and to advance fall prevention in patients with neurological disorders. Fall incidence was assessed in 60 subjects with different neurological disorders. Patients underwent a comprehensive set of functional assessments including instrumented gait analysis, computerized postural assessments and clinical walking tests. Determinants of falls were assessed by binary logistic regression analysis and receiver operator characteristics (ROC). The best single determinant of fallers was a step length reduction at slow walking speed reaching an accuracy of 67.2% (ROC AUC: 0.669; p = 0.027). The combination of 4 spatio-temporal gait parameters including step length and parameters of variability and asymmetry were able to classify fallers and non-fallers with an accuracy of 81.0% (ROC AUC: 0.882; p < 0.001). These findings suggest significant differences in specific spatio-temporal gait parameters between fallers and non-fallers among neurological patients. Fall-related impairments were mainly identified for spatio-temporal gait characteristics, suggesting that instrumented, objective gait analysis is an important tool to estimate patients' fall risk. Our results highlight pivotal fall-related walking deficits that might be targeted by future rehabilitative interventions that aim at attenuating falls.

Portable Device for the Measurement and Assessment of the Human Equilibrium

This work presents the design and development of a new alternative tool to measure the Center of Pressure (CoP) displacements, intended to evaluate the human balance. The device is based on a modified commercial balance board used for video games, resulting in a low-cost, portable device capable of computing the CoP, providing 24 of the most used indexes to test the human balance. The proposed standalone device runs on rechargeable batteries, weighs only 3.5 kg, and has a data storage capacity for over 1000 tests. Visual and auditory instructions assist its user interface. Thus, contrary to the commercial systems designed for laboratory use, this device enables the measurement of quantitative balance parameters in non-laboratory places, allowing the study of the balance of vulnerable populations directly on their typical environments. To evaluate the device, 20 older adults (68.60 ± 1.23 years) were tested, and the resulting values were compared with a similar study using a force platform; 19 indexes showed a similarity with those reported using force platform and 12 of these were statistically equivalent. The proposed device represents an open-source alternative tool for researchers and healthcare personnel to acquire reliable data to evaluate human balance.

Diagnostic Balance Tests for Assessing Risk of Falls and Distinguishing Older Adult Fallers and Non-Fallers: A Systematic Review with Meta-Analysis

Falls are a major cause of injury and morbidity in older adults. To reduce the incidence of falls, a systematic assessment of the risk of falling is of paramount importance. The purpose of this systematic review was to provide a comprehensive comparison of the diagnostic balance tests used to predict falls and for distinguishing older adults with and without a history of falls. We conducted a systematic review of the studies in which instrumented (force plate body sway assessment) or other non-instrumented balance tests were used. We analyzed the data from 19 prospective and 48 retrospective/case-control studies. Among the non-instrumented tests, the single-leg stance test appears to be the most promising for discrimination between fallers and non-fallers. In terms of body sway measures, the center-of-pressure area was most consistently associated with falls. No evidence was found for increased benefit of the body sway test when cognitive tasks were added, or the vision was eliminated. While our analyses are limited due to the unbalanced representation of different test and outcome measures across studies, we can recommend the single-leg test for the assessment of the risk of falling, and the measurements of body sway for a more comprehensive assessment.

Center of pressure displacement characteristics differentiate fall risk in older people: A systematic review with meta-analysis

Falling is the second most prevalent cause of accidental death in the world. Currently available clinical tests to assess balance in older people are insufficiently sensitive to screen for fall risk in this population. Laboratory tests that record the center of pressure (COP) trajectory could overcome this problem but despite their widespread use, the choice of COP trajectory features for use as a biomarker of fall risk lacks consensus. This systematic review and meta-analysis aimed at identifying the best COP characteristics to predict risk of falling in older adults. More than 4000 articles were screened; 44 (7176 older adults) were included in this study. Several COP parameters emerged as good indices to discriminate fallers from non-fallers. From sensitivity analysis, Sway area per unit time, anteroposterior mean velocity, and radial mean velocity were the best traditional features. In this study, identification of older people with a high fall risk was demonstrated using quiet-standing recordings. Such screening would also be useful for routine follow-up of balance changes in older fallers in clinical practice.

'Believe the positive' aggregation of fall risk assessment methods reduces the detection of risk of falling in older adults

OBJECTIVES

Screening programs for fall prevention in older adults may include several assessment methods. This study investigated the validity of aggregating fall risk assessment methods for stratifying the risk of falling in older adults.

METHODS

This secondary data analysis included 52 community-dwelling residents aged [median (interquartile range)] 74 (69-80) years. Fall occurrences were registered prospectively for six months, with 9 (17%) participants reporting at least one fall during follow-up. The fall risk assessment included the Berg Balance Scale (BBS); polypharmacy (POLY); Falls Risk Assessment Score (FRAS); Fall Risk Assessment Tool (FRAT-up); Falls Efficacy Scale (FES); and posturography with the Wii Balance Board (WBB). Aggregation of methods' results was performed according to the risk classification ('high risk' or 'low risk') assigned by their respective cut-off values under the 'believe the positive' (BP) strategy.

RESULTS

Aggregating 1 (POLY), 2 (+BBS), 3 (+FES), 4 (+FRAT-up), 5 (+FRAS), and 6 (+BBS) methods resulted in a monotonic decrease of several validity indices including (index [95% confidence interval]) diagnostic odds ratio (10.82 [2.38-54.28] to 0.59 [0.12-2.09]) and accuracy (0.67 [0.54-0.78] to 0.20 [0.11-0.31]).

CONCLUSIONS

Aggregating fall risk assessment methods-BBS, POLY, FRAS, FRAT-up, FES, WBB-under the BP strategy does not increase the validity of stratification of the risk of falling in older adults.

Relationships Between Body Mass Index and Static and Dynamic Balance in Active and Inactive Older Adults

BACKGROUND AND PURPOSE

Although the association between higher body mass index and poorer balance has been observed in older adults, the role of physical activity in this relationship is not well established. This study aimed to provide scientific evidence about the relationship between body mass index and balance, taking into account the amount of physical activity performed as a confounding variable.

METHODS

We collated cross-sectional data from 160 community-dwelling older adults whom we divided into 3 body mass index categories: normal weight (≥18.50-24.99 kg/m), overweight (25.00-29.99 kg/m), and obese (≥30.00-34.99 kg/m). We classified the participants as inactive or active by means of the Yale Physical Activity Questionnaire. We carried out static and dynamic balance measurements by means of a force platform and through the performance of the Timed Up and Go test, respectively.

RESULTS

We found statistically significant correlations between static balance, dynamic balance, and body mass index in inactive normal (r = 0.280; P = .035; r = 0.300; P = .031) and inactive overweight (r = 0.395; P = .025; r = 0.339; P = .023) people. We observed moderately strong and fair significant correlations between static/dynamic balance and BMI in inactive (r = .603; P = .028; and r = 0.720; P = .020) and active (r = 0.406; P = .037; and r = 0.378; P = .037) obese people, respectively.

CONCLUSION

We conclude that the amount of physical activity performed is a potential contributing factor affecting the association between body mass index and balance in older persons. These findings could be of importance when identifying the main factors that influence postural control among older adults with obesity.

Digital Measurement of Individual Motor and Proprioceptive Skills in Patients with Osteoarthritis of the Knee Prior to Total Knee Replacement

PURPOSE

In spite of consistent improvement in operative methods for total knee arthroplasty, individual motor deficits may lead to a lower outcome. The preoperative classification in individual motoric capacity may get more significance for the future. Complementary to established questionnaires and clinical tests, this pilot study should demonstrate that it is possible to generate a preoperative motor score using a force platform measurement (KMP). Compared to questionnaires the new score represents digital values suitable for everyday clinical use.

METHODS

In total 63 Patients were randomized selected on the day before a bicondylar total knee replacement. A mobile force platform KMP (Motosana) measured the parameter maximum force, power and balance. Fluctuation area was measured in mm² and fluctuation path in mm. One leg standing without holding, transient help or permanent holding at armrests were registered. The force (Newton) was measured while a modified cross lift exercise and power (Watt) by performing five squads.

RESULTS

Based on comprehensive statistical consolidated data of maximum force, power and balance it was possible to create a new motor score "Knie Fit 1.0". Depending on interindividual performance patients were divided into those with higher or lower results. Regarding to their individual motor proprioceptive capacity we could also graduate patients into 4 different groups for force/power and balance. In total 17 of 63 patients offered a complex motor deficit, but on the other hand 17 different patients showed superior results in all categories.

CONCLUSION

It is possible to measure the motor capacity of patients using the mobile force platform (KMP) in everyday clinical practice. Based on this data a new motor score "KnieFit 1.0" was generated and groups of patients with different insufficiencies were created. Further follow-up studies should proof and compare the pre- and postoperative outcome in this field. With "KnieFit 1.0" it may be possible to create an individual perioperative rehabilitation program for compensation of detected deficits.

The Relationship Between Postural Stability, Anthropometry Measurements, Body Composition, and Sport Experience in Judokas with Visual Impairment

Background: Postural stability is quite mandatory when practicing high-performance sports. Investigations of postural stability and related variables in judokas with visual impairment can lead to new training plans targeting the improvement of postural stability and ultimately to enhanced performance. Objectives: To investigate postural stability and its relationship with anthropometric measurements, body composition, and experience in judokas with visual impairment. Methods: Seventeen judokas (70.6% men) with visual impairment participated in this cross-sectional study. The athletes were grouped based on the functional classification of partial (B2/B3, n = 10) and total visual impairment (B1, n = 7). Postural stability was assessed using the elliptical area of the 95% confidence interval (Area) and the average displacement velocity (Vavg) while remaining in a bipedal stance with eyes closed and blindfolded. Body mass, height, circumferences, skinfold thickness and diameters were measured and used to estimate body composition. Between-group comparisons were evaluated using the Mann-Whitney test. Bivariate correlations were determined with Spearman’s correlation coefficient with bootstrap analysis and 95% confidence interval (95% CI) from 500 resamplings. Results: No significant difference was observed between the B1 and B2/B3 groups in relation to postural stability (Area; P = 1.00; Vavg; P = 0.85). Postural stability (Area but not Vavg) correlated positively and moderately (P < 0.05) with anthropometric measurements and negatively with judo experience (practice time). Conclusions: The postural stability of judokas was unrelated to the degree of visual impairment. Postural instability was correlated with anthropometric measurements, mainly body fat and height, and judo experience.

Development and validation of a robotic multifactorial fall-risk predictive model: A one-year prospective study in community-dwelling older adults

BACKGROUND

Falls in the elderly are a major public health concern because of their high incidence, the involvement of many risk factors, the considerable post-fall morbidity and mortality, and the health-related and social costs. Given that many falls are preventable, the early identification of older adults at risk of falling is crucial in order to develop tailored interventions to prevent such falls. To date, however, the fall-risk assessment tools currently used in the elderly have not shown sufficiently high predictive validity to distinguish between subjects at high and low fall risk. Consequently, predicting the risk of falling remains an unsolved issue in geriatric medicine. This one-year prospective study aims to develop and validate, by means of a cross-validation method, a multifactorial fall-risk model based on clinical and robotic parameters in older adults.

METHODS

Community-dwelling subjects aged ≥ 65 years were enrolled. At the baseline, all subjects were evaluated for history of falling and number of drugs taken daily, and their gait and balance were evaluated by means of the Timed "Up & Go" test (TUG), Gait Speed (GS), Short Physical Performance Battery (SPPB) and Performance-Oriented Mobility Assessment (POMA). They also underwent robotic assessment by means of the hunova robotic device to evaluate the various components of balance. All subjects were followed up for one-year and the number of falls was recorded. The models that best predicted falls-on the basis of: i) only clinical parameters; ii) only robotic parameters; iii) clinical plus robotic parameters-were identified by means of a cross-validation method.

RESULTS

Of the 100 subjects initially enrolled, 96 (62 females, mean age 77.17±.49 years) completed the follow-up and were included. Within one year, 32 participants (33%) experienced at least one fall ("fallers"), while 64 (67%) did not ("non-fallers"). The best classifier model to emerge from cross-validated fall-risk estimation included eight clinical variables (age, sex, history of falling in the previous 12 months, TUG, Tinetti, SPPB, Low GS, number of drugs) and 20 robotic parameters, and displayed an area under the receiver operator characteristic (ROC) curve of 0.81 (95% CI: 0.72-0.90). Notably, the model that included only three of these clinical variables (age, history of falls and low GS) plus the robotic parameters showed similar accuracy (ROC AUC 0.80, 95% CI: 0.71-0.89). In comparison with the best classifier model that comprised only clinical parameters (ROC AUC: 0.67; 95% CI: 0.55-0.79), both models performed better in predicting fall risk, with an estimated Net Reclassification Improvement (NRI) of 0.30 and 0.31 (p = 0.02), respectively, and an estimated Integrated Discrimination Improvement (IDI) of 0.32 and 0.27 (p<0.001), respectively. The best model that comprised only robotic parameters (the 20 parameters identified in the final model) achieved a better performance than the clinical parameters alone, but worse than the combination of both clinical and robotic variables (ROC AUC: 0.73, 95% CI 0.63-0.83).

CONCLUSION

A multifactorial fall-risk assessment that includes clinical and hunova robotic variables significantly improves the accuracy of predicting the risk of falling in community-dwelling older people. Our data suggest that combining clinical and robotic assessments can more accurately identify older people at high risk of falls, thereby enabling personalized fall-prevention interventions to be undertaken.

Age-Related Changes in Postural Control in Physically Inactive Older Women

BACKGROUND AND PURPOSE

The maintenance of postural control is influenced by the complexity of a given task. Tasks that require greater attention and cognitive involvement increase the risk of falls among older adults. The aim of the present study was to evaluate the adaptation of the postural control system to different levels of task complexity in physically inactive young and older women.

METHODS

A cross-sectional study was conducted with adult women classified as physically inactive based on the results of the International Physical Activity Questionnaire. The participants were 27 young (20-30 years of age) and 27 older (60-80 years of age) women. Sway velocity of the center of pressure in the anterior-posterior and medial-lateral directions was calculated using a force plate under 6 conditions: standing directly on the force plate or on a foam placed over the force plate, eyes open or closed, and dual-task complexity with and without the foam.

RESULTS AND DISCUSSION

A 2-way analysis of variance revealed that sway velocity increased in both groups when the task conditions were altered. The older women exhibited significantly greater sway velocity compared with the young women on all tasks. However, the patterns of postural control adaptation to the different levels of complexity were similar among all participants.

CONCLUSIONS

In this study, the adaption of the postural control system to different levels of task complexity did not differ between physically inactive young and physically inactive older women. However, the physically inactive older women exhibited greater sway velocity compared with the young women.

Identification of elders at higher risk for fall with statewide electronic health records and a machine learning algorithm

OBJECTIVE

Predicting the risk of falls in advance can benefit the quality of care and potentially reduce mortality and morbidity in the older population. The aim of this study was to construct and validate an electronic health record-based fall risk predictive tool to identify elders at a higher risk of falls.

METHODS

The one-year fall prediction model was developed using the machine-learning-based algorithm, XGBoost, and tested on an independent validation cohort. The data were collected from electronic health records (EHR) of Maine from 2016 to 2018, comprising 265,225 older patients (≥65 years of age).

RESULTS

This model attained a validated C-statistic of 0.807, where 50 % of the identified high-risk true positives were confirmed to fall during the first 94 days of next year. The model also captured in advance 58.01 % and 54.93 % of falls that happened within the first 30 and 30-60 days of next year. The identified high-risk patients of fall showed conditions of severe disease comorbidities, an enrichment of fall-increasing cardiovascular and mental medication prescriptions and increased historical clinical utilization, revealing the complexity of the underlying fall etiology. The XGBoost algorithm captured 157 impactful predictors into the final predictive model, where cognitive disorders, abnormalities of gait and balance, Parkinson's disease, fall history and osteoporosis were identified as the top-5 strongest predictors of the future fall event.

CONCLUSIONS

By using the EHR data, this risk assessment tool attained an improved discriminative ability and can be immediately deployed in the health system to provide automatic early warnings to older adults with increased fall risk and identify their personalized risk factors to facilitate customized fall interventions.

Robotic balance assessment in community-dwelling older people with different grades of impairment of physical performance

BACKGROUND

Impaired physical performance is common in older adults and has been identified as a major risk factor for falls. To date, there are no conclusive data on the impairment of balance parameters in older subjects with different levels of physical performance.

AIMS

The aim of this study was to investigate the relationship between different grades of physical performance, as assessed by the Short Physical Performance Battery (SPPB), and the multidimensional balance control parameters, as measured by means of a robotic system, in community-dwelling older adults.

METHODS

This study enrolled subjects aged ≥ 65 years. Balance parameters were assessed by the hunova robot in static and dynamic (unstable and perturbating) conditions, in both standing and seated positions and with the eyes open/closed.

RESULTS

The study population consisted of 96 subjects (62 females, mean age 77.2 ± 6.5 years). According to their SPPB scores, subjects were separated into poor performers (SPPB < 8, n = 29), intermediate performers (SPPB = 8-9, n = 29) and good performers (SPPB > 9, n = 38). Poor performers displayed significantly worse balance control, showing impaired trunk control in most of the standing and sitting balance tests, especially in dynamic (both with unstable and perturbating platform/seat) conditions.

CONCLUSIONS

For the first time, multidimensional balance parameters, as detected by the hunova robotic system, were significantly correlated with SPPB functional performances in community-dwelling older subjects. In addition, balance parameters in dynamic conditions proved to be more sensitive in detecting balance impairments than static tests.

Postural Stability in Obese Preoperative Bariatric Patients Using Static and Dynamic Evaluation

INTRODUCTION

Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI.

SUBJECTS AND METHODS

Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened.

RESULTS

Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects' eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04).

DISCUSSION AND CONCLUSION

Importantly, these data highlight obesity's contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.

Static balance in older adults with chronic obstructive pulmonary disease undergoing pulmonary rehabilitation

OBJECTIVE: To compare balance between older adults with and without chronic obstructive pulmonary disease (COPD) in tasks involving proprioceptive changes and respiratory muscle load, and to investigate the association between balance, functional capacity, and peripheral and respiratory muscle strength. METHODS: Fourteen older adults with COPD undergoing pulmonary rehabilitation and nine older adults without pulmonary disease were evaluated for static balance on a force platform under four conditions: eyes open, eyes closed, eyes closed on foam, and eyes open with respiratory overload. Differences between groups, among conditions and group/condition interactions, were tested using two-way ANOVA. Associations were explored using Pearson’s correlation coefficient. RESULTS: No differences in the posturographic variables were found in the group/condition interactions (p ≥ 0.23). The COPD group exhibited greater total displacement (F = 8.79, p = 0.003), mediolateral sway (F = 4.01, p = 0.04) and anteroposterior velocity (F = 4.28, p = 0.04) in the group effect analysis. Significant differences were found between eyes closed on foam and other conditions for all posturographic variables: anteroposterior sway (F = 13.39), mediolateral sway (F = 28.58), total displacement (F = 59.4), area (F = 37.68), anteroposterior velocity (F = 26.42), and mediolateral velocity (F = 33.29), in the condition effect analysis (p < 0.001, post-hoc). In the COPD group, significant correlations were found between the Glittre-ADL test, anteroposterior sway (r = 0.68, p = 0.01), and anteroposterior velocity (r = 0.67, p = 0.009); the 6MWT was also correlated with anteroposterior velocity (r = 0.59, p = 0.03). CONCLUSION: Older adults with COPD present balance deficits compared to healthy individuals. The unstable surface caused greater postural instability compared to other conditions in both groups. Impaired balance was associated with reduced physical function and exercise capacity.

Influence of strength training and multicomponent training on the functionality of older adults: systematic review and meta-analysis

Abstract Physical exercise is an important option to maintain functional independence in older adults, however, it is not clear which type of exercise is the most benefic: strength or multicomponent. The objective was to verify the effectiveness of strength training and multicomponent training on functionality of healthy older patients through a systematic review with meta-analysis. Registration number: CRD42017071887. Two independent evaluators searched Pubmed, Web of Science, PEDro, Cochrane and Lilacs databases. Of the 1434 studies found, 32 clinical trials that investigated the effects of strength training only and/or combined with other modalities (multicomponent) in older adults and evaluated the Timed up and Go (TUG), sit-to-stand (STS) and/or Berg Balance Scale (BBS were included. The methodological quality was evaluated with the Downs & Black scale. Data analysis was performed with the Software Review Manager. It was verified improvement in all the investigated outcomes when performing multicomponent training in comparison to control groups. Strength training, compared to control groups, showed benefit only for sit to stand test. Studies comparing the two trainings found no difference between them. The not high average score in the methodological quality assessment of the included studies is a limitation of the present study. In conclusion, both types of training were effective to improve functionality and are good strategies of training for older individuals. However, as the comparison between the two types of training was performed in few studies, it is not possible to infer which is more effective for the functionality, suggesting the realization of new clinical trials.

Posturographic measures did not improve the predictive power to identify recurrent falls in community-dwelling elderly fallers

OBJECTIVE

This study aimed to evaluate if posturography can be considered a recurrent fall predictor in elderly individuals.

METHODS

This was a cross-sectional study. A total of 124 subjects aged 60 to 88 years were evaluated and divided into two groups-the recurrent fallers (89) and single fallers (35) groups. Patients' sociodemographic characteristics were assessed, and clinical testing was performed. The functional test assessment instruments used were timed up and go test (TUGT), Berg Balance Scale (BBS), five times sit-to-stand test, and Falls Efficacy Scale (to measure fear of falling). Static posturography was performed in a force platform in the following three different situations-eyes open (EO), eyes closed (EC), and EO dual task.

RESULTS

There were significant differences between the single and recurrent fallers groups regarding the fear of falling, the Geriatric Depression Scale score, the mean speed calculated from the total displacement of the center point of pressure (COP) in all directions with EO, and the root mean square of the displacement from the COP in the mediolateral axis with EC. Based on the hierarchical logistic regression model, none of the studied posturographic variables was capable of significantly increasing the power of differentiation between the recurrent and single fallers groups. Only TUGT with a cognitive distractor (p<0.05) and the BBS (p<0.01) presented with significant independent predictive power.

CONCLUSION

TUGT with a cognitive distractor and the BBS were considered recurrent fall predictors in elderly fallers.

Relative importance of vision and proprioception in maintaining standing balance in people with multiple sclerosis

BACKGROUND

Balance impairment is common and a risk factor of falls in people with multiple sclerosis (MS). The purpose of this study was to evaluate the relative importance between vision and proprioception in maintaining standing body balance among individuals with MS compared with healthy individuals.

METHODS

Thirty people with MS (the mean ± standard deviation of the Patient Determined Disability Steps: 3.62 ± 1.67 out of 8) and 25 healthy adults participated in this cross-sectional study. They underwent a static posturography test, consisting of three sensory feedback conditions: eyes open on a firm surface, eyes closed on a firm surface, and eyes open on a compliant surface. Their standing balance performance, quantified by the 95% confidence ellipse area and the total length of the center of pressure trajectory during each sensory condition, was calculated based on the ground reaction force data. The Romberg's quotient (the ratio of the center of pressure measurements on the firm surface between eyes open and eyes closed conditions) and proprioception quotient (the ratio of the center of pressure measurements with eyes open between firm and compliant standing surfaces) were calculated and compared between groups.

RESULTS

Persons with MS demonstrated significantly larger postural sway under all three sensory conditions than their healthy counterparts. The reliance on the vision and proprioception systems in maintaining body balance was greater among people with MS compared to healthy adults. Both groups similarly relied more on the proprioceptive input to keep body balance than on the vision.

CONCLUSIONS

Like healthy individuals, persons with MS rely more on proprioception to maintain body balance than vision. Our findings could provide preliminary reference for optimizing balance improving programs aimed at person with MS.

Agreement and predictive power of six fall risk assessment methods in community-dwelling older adults

A large number of fall risk assessment methods are available with a variety of performances for screening the risk of falling in older adults, but their agreement for assessing the risk of falling remains unknown. This observational prospective cohort study describes the agreement and predictive power of methods to classify the risk of falling in older adults using prospective data and published cut-off values. Fifty-two participants aged 74 years (interquartile range 69-80) were assessed using the Berg Balance Scale, polypharmacy, Falls Risk Assessment Score, Fall Risk Assessment Tool, Fall Efficiency Scale, and Posturography. Nine participants (17 %) reported at least one fall after six months. Cochran's test showed different proportions of participants classified as at high risk of falling among all methods (Q = 69.560, p < 0.001). A slightly better-then-chance agreement was estimated between all FRA methods (Light's κ = 0.074, 95%CI [0.021; 0.142]). We found both global and pairwise agreement levels that question the agreement among fall risk assessment methods for screening community-dwelling older adults.

Test-retest reliability and minimal detectable change of the computerized dynamic posturography PROPRIO for adults with chronic traumatic brain injury

PURPOSE

Balance deficits after brain injury, including reactive recovery from unexpected perturbations, can persist well after rehabilitation is concluded. While traditional clinical assessments are practical, the anticipatory nature of the tasks may mask perceptible balance control. Computerized dynamic posturography can directly quantify capacity to respond to unexpected, external perturbations. This study examined the reliability of the computerized dynamic posturography assessment with the device PROPRIO^® 4000 in adults with traumatic brain injury and created the minimal detectable change for its standardized test.

METHODS

Ten adults (ages 21-55 years) with chronic (average 10 ± 6 years post-injury) severe (loss of consciousness 2-75 days) brain injury performed three trials of the Propriotest^® on two separate days. The average of three trials and the best scores were used separately for analysis. Test-retest reliability was verified using Intraclass Correlation Coefficients with 95% confidence interval and standard error of measurement in relation to the Intraclass Correlation Coefficients at 95%. The minimal detectable change was calculated at 95% confidence level (minimal detectable change₉₅) and Bland-Altman plots were created to express agreement between measurement days.

RESULTS

The results exhibited excellent reliability for both average (Intraclass Correlation Coefficient of 0.969, standard error of measurement 50.9 points) and best (Intraclass Correlation Coefficient of 0.985, standard error of measurement 31.3 points) scores, with average and best minimal detectable change₉₅ of 141.0 and 86.7 points, respectively.

CONCLUSIONS

Clinicians and rehabilitation researchers can use these findings to determine if a Propriotest^® change score represents a true post-treatment effect with adults with chronic brain injury.IMPLICATIONS FOR REHABILITATIONAfter brain injury, balance deficits are common and can persist well after completion of rehabilitation programs.Computerized dynamic posturography allows for objective quantification of one's capacity to respond to external perturbations.The device PROPRIO^® 4000 provides reliable quantification of balance deficits of community dwelling individuals who have experienced a severe traumatic brain injury.The minimal detectable change scores created can assist clinicians and rehabilitation researchers detect whether a change in balance score represents a true effect of an intervention at post-treatment.

The Effects of Textured Insoles on Cortical Activity and Quiet Bipedal Standing With and Without Vision: An EEG Study

Wearing textured insoles (TIs) can reduce static postural sway, but the neurophysiological mechanisms by which these changes occur are not well understood. To address this issue, cortical activity was investigated in this study using electroencephalography (EEG) recordings from 19 scalp locations, in 15 healthy young adults (5 females; mean age = 27 ± 4.09 years) during quiet bipedal standing, under different insole conditions (textured versus smooth), with and without vision. Compared to smooth insoles (SIs), TIs significantly reduced postural sway in two measures; anterior-posterior range and standard deviation. In the EEG data, whole-head analyses showed cortical activity in the upper alpha power band was significantly reduced for textured compared to SIs. Exploratory analyses revealed this effect was significant both with and without vision, and was more pronounced over the parietal, compared to central regions, and over central compared to frontal regions. This trend was observed in low alpha and theta bands, but the effect of insole type was not significant. Textured insoles thus appear to affect not only balance outcomes but also cortical activity. The cortical activity adaptation may represent greater information becoming readily available at the cortical level, enhancing the representation of the body in space.

Towards computerized diagnosis of neurological stance disorders: data mining and machine learning of posturography and sway

We perform classification, ranking and mapping of body sway parameters from static posturography data of patients using recent machine-learning and data-mining techniques. Body sway is measured in 293 individuals with the clinical diagnoses of acute unilateral vestibulopathy (AVS, n = 49), distal sensory polyneuropathy (PNP, n = 12), anterior lobe cerebellar atrophy (CA, n = 48), downbeat nystagmus syndrome (DN, n = 16), primary orthostatic tremor (OT, n = 25), Parkinson's disease (PD, n = 27), phobic postural vertigo (PPV n = 59) and healthy controls (HC, n = 57). We classify disorders and rank sway features using supervised machine learning. We compute a continuous, human-interpretable 2D map of stance disorders using t-stochastic neighborhood embedding (t-SNE). Classification of eight diagnoses yielded 82.7% accuracy [95% CI (80.9%, 84.5%)]. Five (CA, PPV, AVS, HC, OT) were classified with a mean sensitivity and specificity of 88.4% and 97.1%, while three (PD, PNP, and DN) achieved a mean sensitivity of 53.7%. The most discriminative stance condition was ranked as "standing on foam-rubber, eyes closed". Mapping of sway path features into 2D space revealed clear clusters among CA, PPV, AVS, HC and OT subjects. We confirm previous claims that machine learning can aid in classification of clinical sway patterns measured with static posturography. Given a standardized, long-term acquisition of quantitative patient databases, modern machine learning and data analysis techniques help in visualizing, understanding and utilizing high-dimensional sensor data from clinical routine.

Relationship Between L4/5 Lumbar Multifidus Cross-Sectional Area Ratio and Fall Risk in Older Adults with Lumbar Spinal Stenosis: A Retrospective Study

Various factors, including spinal deformities and trunk muscle atrophy, greatly affect the fall risk among older adults with lumbar spinal stenosis (LSS). However, the etiology of falls in older adults with degenerative LSS and trunk muscle atrophy is poorly understood. We investigated the association between trunk muscle atrophy and falls in older LSS patients. This retrospective study included 99 hospitalized older adults with LSS. Participants completed self-reported fall score questionnaires and were divided into the fall risk (n = 30) and non-fall risk (n = 69) groups. The patients' low back pain visual analog scale score, Geriatric Depression Scale score, sagittal vertical axis, L4/5 lumbar multifidus cross-sectional area ratio (LMCSAR), and center of pressure (COP) values during quiet standing were evaluated. The fall risk group had a lower L4/5 LMCSAR (p = 0.002) and increased COP excursion (p = 0.034) than the non-fall risk group. No significant differences were observed in the other measured variables between the two groups. The L4/5 LMCSAR (p < 0.001) and COP (p = 0.024) were related to fall risk and may be useful in fall risk assessment in such populations. Strategies aimed at enhancing controlled lumbar segmental motion and improving trunk muscle stability or mass may decrease the fall risk in this cohort.

Fast and automatic assessment of fall risk by coupling machine learning algorithms with a depth camera to monitor simple balance tasks

BACKGROUND

Falls in the elderly constitute a major health issue associated to population ageing. Current clinical tests evaluating fall risk mostly consist in assessing balance abilities. The devices used for these tests can be expensive or inconvenient to set up. We investigated whether, how and to which extent fall risk could be assessed using a low cost ambient sensor to monitor balance tasks.

METHOD

Eighty four participants, forty of which were 65 or older, performed eight simple balance tasks in front of a Microsoft Kinect sensor. Custom-made algorithms coupled to the Kinect sensor were used to automatically extract body configuration parameters such as body centroid and dispersion. Participants were then classified in two groups using a clustering method. The clusters were formed based on the parameters measured by the sensor for each balance task. For each participant, fall risk was independently assessed using known risk factors as age and average physical activity, as well as the participant's performance on the Timed Up and Go clinical test.

RESULTS

Standing with a normal stance and the eyes closed on a foam pad, and standing with a narrow stance and the eyes closed on regular ground were the two balance tasks for which the classification's outcome best matched fall risk as assessed by the three known risk factors. Standing on a foam pad with eyes closed was the task driving to the most robust results.

CONCLUSION

Our method constitutes a simple, fast, and reliable way to assess fall risk more often with elderly people. Importantly, this method requires very little space, time and equipment, so that it could be easily and frequently used by a large number of health professionals, and in particular by family physicians. Therefore, we believe that the use of this method would substantially contribute to improve fall prevention.

TRIAL REGISTRATION

CER-VD 2015-00035. Registered 7 December 2015.

Postural stability in Parkinson's disease patients' wives and in elderly women leading different lifestyles

The study aimed to determine postural stability of Parkinson's disease (PD) patients' wives in comparison with women differing in their lifestyle. (PD) patients' wives (n = 44), homemakers (n = 41), and female students of the University of the Third Age (n = 43) performed balance tests on a stabilometric platform. The PD patients' wives were characterized by significantly (p < 0.001) higher values of mean velocity sway than the homemakers and students (approximately 3.5 and 5 mm/s, respectively) and performed worst in displacement velocity and sway range in both sagittal and frontal plane. The results indicate that the wives of PD patients need support in the area of health training targeted at improving their standing stability.

Concurrent Validity of Postural Sway Measures in Older Adults with Cognitive Impairment

Aims

To examine concurrent validity of inertial sensor (APDM ISway) versus force plate center of pressure (COP) measures of postural sway in cognitively impaired older adults.

Methods

Participants, mean age 85.6 (SD 4.8), were tested in 4 static standing conditions: (1) eyes open/normal base, (2) eyes open/narrow base, (3) eyes closed/normal base, and (4) eyes closed/narrow base. ISway and COP measures were collected.

Results

Strong correlations between ISway trunk sway smoothness [ISway JERK, (m ² /s ⁵ )] and COP path length (r = 0.67-0.85) and COP mean velocity (r = 0.77-0.87); also ISway total sway acceleration path length/trail duration [ISway PATH, (m²/s²)] and COP path length (r = 0.77-0.87) and COP mean velocity (r = 0.77-0.91). Increased sway was detected in narrow versus normal base and eyes closed versus open conditions (P = .001).

Conclusions

APDM ISway demonstrated concurrent validity to force-plate COP and changes in postural sway were detected between conditions.

Community-dwelling adults with a history of falling report lower perceived postural stability during a foam eyes closed test than non-fallers

Perceived postural stability has been reported to decrease as sway area increases on firm surfaces. However, changes in perceived stability under increasingly challenging conditions (e.g., removal of sensory inputs) and the relationship with sway area are not well characterized. Moreover, whether perceived stability varies as a function of age or history of falls is unknown. Here we investigate how perceived postural stability is related to sway area and whether this relationship varies as a function of age and fall history while vision and proprioceptive information are manipulated. Sway area was measured in 427 participants from the Baltimore Longitudinal Study of Aging while standing with eyes open and eyes closed on the floor and a foam cushion. Participants rated their stability [0 (completely unstable) to 10 (completely stable)] after each condition, and reported whether they had fallen in the past year. Perceived stability was negatively associated with sway area (cm²) such that individuals who swayed more felt less stable across all conditions (β = - 0.53, p < 0.001). Perceived stability decreased with increasing age (β = - 0.019, p < 0.001), independent of sway area. Fallers had a greater decline in perceived stability across conditions (F = 2.76, p = 0.042) compared to non-fallers, independent of sway area. Perceived postural stability declined as sway area increased during a multisensory balance test. A history of falling negatively impacts perceived postural stability when vision and proprioception are simultaneously challenged. Perceived postural stability may provide additional information useful for identifying individuals at risk of falls.

Standing Versus Stepping-Exploring the Relationships Between Postural Steadiness and Dynamic Reactive Balance Control

While the literature has characterized balance control during quasi-static and/or dynamic tasks, comparatively few studies have examined relationships across paradigms. This study investigated whether quiet-stance postural steadiness metrics were associated with reactive control parameters (during both stepping and restabilization phases) following a lean-and-release perturbation. A total of 40 older adults participated. Postural steadiness (center of the pressure range, root mean square, velocity, and frequency) was evaluated in "feet together" and "tandem stance" positions. During the reactive control trials, the step length, step width, movement time, and reaction time were measured, in addition to the postural steadiness variables measured during the restabilization phase following the stepping response. Out of 64 comparisons, only 10 moderate correlations were observed between postural steadiness and reactive spatio-temporal stepping parameters (P ≤ .05, r = -.312 to -.534). However, postural steadiness metrics were associated with the center of pressure velocity and frequency during the restabilization phase of the reactive control trials (P ≤ .02, r = .383 to .775 for velocity and P ≤ .01, r = .386 to .550 for frequency). Although some elements of quasi-static center of pressure control demonstrated moderate associations with dynamic stepping responses, relationships were stronger for restabilization phase dynamics after foot-contact. Future work should examine the potential association between restabilization phase control and older adult fall-risk.

Day-to-day variations in sleep quality affect standing balance in healthy adults

Acute sleep deprivation is known to affect human balance and posture control. However, the effects of variations in sleep quality and pattern over consecutive days have received less attention. This study investigated the associations between day-to-day variations in sleep quality and standing balance in healthy subjects. Twenty volunteers (12 females and 8 males; age: 28.8 ± 5.7 years, body mass index: 23.4 ± 3.4 kg/m2, resting heart rate: 63.1 ± 8.7 bpm) with no history of sleep disorders or balance impairments participated in the study. Sleep and balance were assessed over two consecutive days. Sleep quality variations were assessed using sleep diary, actigraphy and heart rate variability (HRV) measures. Sleep was monitored at home, using an unobtrusive wearable device. Balance was assessed in a gait lab using foot centre of pressure (COP) displacement during quiet standing. Subjects with a day-to-day deterioration in sleep quantity and quality (i.e., decreased duration and increased fragmentation, increased nocturnal activity and decreased HRV) exhibited significant changes in balance (i.e., larger COP area, amplitude and standard deviation). Conversely, subjects with no significant alterations in sleep quantity and quality showed no significant changes in COP displacements. These results confirmed our hypothesis that changes in sleep quality and pattern over consecutive days may affect balance.

One-legged stance sway of older adults with and without falls

Postural instability is a common problem among older people, and it is associated with mobility impairments, activity limitation and fear of falling. The evaluation of postural control can contribute to the early detection of balance deficits and help health professionals to manage this problem to prevent falls in older adults. The aim of this study was to identify center of pressure cut-offs to differentiate between older adults with and without falls in the past 12 months. The participants were 170 older adults (mean age 67 years, 50 fallers and 120 non-fallers). Center of pressure area and sway velocity in the anterior-posterior and medio-lateral directions were assessed using a force platform during three 30s one-legged stance trials with eyes open. The mean across trials was used for analysis. The time-limit (how long the participant was able to stay in one-legged stance, up to 30s) was also assessed. Fallers had poorer postural control than non-fallers (effect size ≥ 0.52, P <0.05). The cut-offs identified were 10.3 cm² for Center of pressure area, 2.9 cm/s for velocity in the anterior-posterior, and 3.4 cm/s for medio-lateral velocity. The force platform parameters obtained an area under the curve of 0.72, with sensitivity of 78% and specificity of 68%. There were no significant differences between non-fallers and fallers for time-limit variable (17 seconds vs. 18 seconds). Force platform parameters during one-legged stance were associated with history of falls in older adults. The cut-offs obtained acceptable area under curve, sensitivity and specificity, with center of pressure area presenting the best performance to differentiate between fallers and non-fallers.

Intra-rater reliability of hip abductor isometric strength testing in a standing position in older fallers and non-fallers

Background

Reduced hip muscle strength has been shown to be a major factor related to falls in older persons. However, comprehensive assessment of hip abduction strength in the clinical setting is challenging. The aim of this study was to investigate the feasibility and intra-rater reliability of a quick and simple hip abductor strength test in a functional standing position.

Methods

Individuals over 65 years of age were recruited from the geriatric department of a university hospital and an outpatient clinic. Thirty-two older subjects, including 16 fallers (≥1 fall during the last 12 months) and 16 non-fallers were included. Maximum voluntary isometric strength (MVIS) and rate of force generation (RFG) of the hip abductors of the right leg were evaluated in a standing position using a hand-held dynamometer. Two test-sessions were carried out. All hip strength values were normalized to participants’ weight. Reliability was determined using the intra-class correlation coefficient agreement (ICC_agreement), the standard error of measurement (SEM) and a Bland and Altman analysis (BA).

Results

All participants completed the strength tests, which took a mean 2.47 ± 0.49 min (one limb). Intra-rater reliability was higher for MVIS (0.98_{[0.95–0.99]}) than RFG (ICC = 0.93_{[0.87–0.97]}) for the entire sample. In the non-fallers, ICC was 0.98_{[0.95–1.00]} (SEM = 0.08 N.kg^− 1) for MVIS and 0.88_{[0.75–0.96]} for RFG (SEM = 1.34 N.kg^-1.s^-1). In the fallers, ICC was 0.94_{[0.89–0.98]} (SEM = 0.11 N.kg^− 1) for MVIS and 0.93_{[0.84–0.98]} (SEM = 1.12 N.kg^− 1.s^− 1) for RFG. The BA plot showed that the MVIS and RFG values did not differ across test-sessions, showing that no learning effect occurred (no systematic effect). The mean differences between test-sessions were larger and the LOA smaller in the fallers than in the non-fallers.

Conclusion

Assessment of hip strength in a standing position is feasible, rapid and reliable. We therefore recommend this position for clinical practice. Future studies should investigate the diagnostic value of hip abductor strength in standing to discriminate between fallers and non-fallers, and to determine if change in strength following a falls prevention program reduces the risk of falls.

Detraining effects of regular Tai Chi exercise on postural control ability in older women: A randomized controlled trial

BACKGROUND/OBJECTIVE

This study aimed to investigate the training and detraining effects of Tai Chi (TC) on postural control ability in single leg stance (SLS) by conducting a single-blind randomized controlled trial.

METHOD

Forty-eight older women were randomly divided into the TC, brisk walking (BW), and control(C) groups by using computer-generated program. The participants completed a 16-week intervention training and 8-week detraining program. Postural control ability in SLS was tested at the baseline, 16 t h, 20 t h, and 24 t h weeks. The primary outcomes included single-leg stance time (Time) and secondary outcomes included maximal displacement of the center of pressure (COP) in the anterior-posterior (AP) direction (D-ap), maximal displacement of the COP in the medial-lateral (ML) direction (D-ml), total length of the COP trajectories (Lng), and 95% confidence ellipse area of the COP movements (area), mean AP total excursion velocities (V-ap), and mean ML total excursion velocities (V-ml).

RESULTS

Significant within-group difference compared with the baseline and between-groups difference compared with control group were found at 16 t h, 20 t h, and 24 t h weeks in the TC group and at the 16 t h and 20 t h weeks in the BW group in all the primary and secondary outcomes. Most of secondary outcomes including Lng, D-ml, V-ml, Area increased significantly at the 24 t h week compared with that at the 16 t h week in BW group.

CONCLUSIONS

TC was effective in improving postural control ability and maintaining intervention gains, and was recommended as an appropriate exercise to prevent falls in the older adults.

Proprioceptive impairments in high fall risk older adults: the effect of mechanical calf vibration on postural balance

Background

Impairments in proprioceptive mechanism with aging has been observed and associated with fall risk. The purpose of the current study was to assess proprioceptive deficits among high fall risk individuals in comparison with healthy participants, when postural performance was disturbed using low-frequency mechanical gastrocnemius vibratory stimulation.

Methods

Three groups of participants were recruited: healthy young (n = 10; age = 23 ± 2 years), healthy elders (n = 10; age = 73 ± 3 years), and high fall risk elders (n = 10; age = 84 ± 9 years). Eyes-open and eyes-closed upright standing balance performance was measured with no vibration, and 30 and 40 Hz vibration of both calves. Vibration-induced changes in balance behaviors, compared to baseline (no vibratory stimulation) were compared between three groups using multivariable repeated measures analysis of variance models.

Results

Overall, similar results were observed for two vibration frequencies. However, changes in body sway due to vibration were more obvious within the eyes-closed condition, and in the medial–lateral direction. Within the eyes-closed condition high fall risk participants showed 83% less vibration-induced change in medial–lateral body sway, and 58% less sway velocity, when compared to healthy participants (p < 0.001; effect size = 0.45–0.64).

Conclusions

The observed differences in vibration effects on balance performance may be explained by reduced sensitivity in peripheral nervous system among older adults with impaired balance.

Fall Risk Assessment Metrics for Elderly Patients With Hip Fractures

The most common surgery performed by orthopedic surgeons likely involves that for hip fractures. The incidence of hip fractures is anticipated to rise in the coming decades. Hip fractures most commonly occur in elderly women with osteoporosis after a fall from standing position. In an effort to reduce the incidence, improve the postoperative care, and accelerate the rehabilitation of hip fractures, it is important to evaluate the fall risk of these patients, as it is an objective indication of their level of physical activity. Metrics currently available for the evaluation of fall risk in the elderly vary widely, with each having been designed to assess a specific patient population. However, their applicability has often proved to be much broader than expected. This review summarizes the metrics available for fall risk assessment of elderly patients with hip fractures, describes their individual features and efficacy, and highlights those that seem to be more reliable for the assessment of rehabilitation of these patients after hip fracture surgery. [Orthopedics. 2018; 41(3):142-156.].

Low intensity vibration of ankle muscles improves balance in elderly persons at high risk of falling

In our study we examined postural performance of young healthy persons (HY), elderly healthy persons (HE), and elderly persons at high risk of falling (FR). Anterio-posterior (AP) and medio-lateral (ML) ankle and hip angular deviations, as well as linear displacements of the center of mass (COM) were assessed in persons standing with eyes either open or closed, while none, and 40 and 30 Hz vibrations were applied bilaterally to the ankle muscle gastrocnemius. During quiet standing with eyes open, balance parameters in FR group differed from those in healthy groups. ML ankle and hip angular deviations, as well as COM linear displacements were noticeably larger in FR group. During quiet standing with eyes closed, all balance parameters in participants of all groups had a clear trend to increase. During standing with eyes open, 40 Hz vibration increased all but one balance parameter within HY group, ankle angular deviations in HE group, but none in FR group. In response to 30 Hz vibration, only ankle angular deviations and COM linear displacements increased in HY group. There were no changes in both elderly groups. During standing with eyes closed, 40 and 30 Hz vibrations did not produce consistent changes in balance parameters in HY and HE groups. In FR persons, 40 Hz vibration did not change balance parameters. However, in FR groups, 30 Hz vibration decreased ankle and hip angular deviations, and COM linear displacements. The major result of the study is a finding that low intensity vibration of ankle muscles makes balance better in elderly persons at high risk of falling. This result is clinically relevant because it suggests that applying mild vibration to ankle muscles while standing and walking might benefit elderly persons, improving their postural performance and reducing a risk of unexpected falls.

Destabilization of the Upright Posture Through Elevation of the Center of Mass

The inverted pendulum model predicts that the major challenge for neural control of the upright posture is the inherent instability of the body due to the center of mass (COM) being above the base of support (BOS). If so, even slight elevation of the COM may substantially destabilize posture. The destabilizing effect of heavy load positioned above the COM has been demonstrated. We examined sensitivity of posture to light (1-5% of body weight) load by placing weights on the shoulders and assessing functional reach distance in the forward, right, and left directions and postural sway during quiet stance. At each load level, the quiet stance task was tested with and without vision. The 1% of body weight load significantly shortened reach distance in the forward direction. It also increased postural sway. Interestingly, additional weight did not result in further deficits. The results support high sensitivity of postural stability to COM elevation that increases the challenge for neural control of posture and that can potentially be used for early detection of declines in postural stability.

Assessing balance through the use of a low-cost head-mounted display in older adults: a pilot study

Introduction

As the population ages, the prevention of falls is an increasingly important public health problem. Balance assessment forms an important component of fall-prevention programs for older adults. The recent development of cost-effective and highly responsive virtual reality (VR) systems means new methods of balance assessment are feasible in a clinical setting. This proof-of-concept study made use of the submillimeter tracking built into modern VR head-mounted displays (VRHMDs) to assess balance through the use of visual–vestibular conflict. The objective of this study was to evaluate the validity, acceptability, and reliability of using a VRHMD to assess balance in older adults.

Materials and methods

Validity was assessed by comparing measurements from the VRHMD to measurements of postural sway from a force plate. Acceptability was assessed through the use of the Simulator Sickness Questionnaire pre- and postexposure to assess possible side effects of the visual–vestibular conflict. Reliability was assessed by measuring correlations between repeated measurements 1 week apart. Variables of possible importance that were found to be reliable (r≥0.9) between tests separated by a week were then tested for differences compared to a control group. Assessment was performed as a cross-sectional single-site community center-based study in 13 older adults (≥65 years old, 80.2±7.3 years old, 77% female, five at risk of falls, eight controls). The VR balance assessment consisted of four modules: a baseline module, a reaction module, a balance module, and a seated assessment.

Results

There was a significant difference in the rate at which participants with a risk of falls changed their tilt in the anteroposterior direction compared to the control group. Participants with a risk of falls changed their tilt in the anteroposterior direction at 0.7°/second vs 0.4°/second for those without a history of falls. No significant differences were found between pre/postassessment for oculomotor score or total Simulator Sickness Questionnaire score. Both the force plate and the head-mounted display balance-assessment system were able to detect differences between conditions meant to mask visual and proprioceptive information.

Conclusion

This VRHMD is both affordable and portable, causes minimal simulator sickness, and produces repeatable results that can be used to assess balance in older adults.