Enhancing Footwear Safety for Fall Prevention in Older Adults: A Comprehensive Review of Design Features.

BACKGROUND: Falls are a global concern affecting people of all ages; however, older adults are particularly vulnerable to age-related factors and foot-related issues. Footwear is critical for preventing falls, as it provides stability and protection against slips, trips, and falls (STFs). However, a significant gap exists in the systematic exploration of the safety aspects of footwear design for fall prevention in older adults. METHODS: This comprehensive review applied a meticulous search strategy encompassing prominent databases, including Google Scholar, ScienceDirect, SCOPUS, MEDLINE, ResearchGate, and PubMed. This review synthesized and analyzed existing research to bridge knowledge gaps and provide insights into optimal footwear choices for older adults in terms of design features such as fit, fixation, heel height, collar height, slip resistance, and sole/insole hardness. RESULTS: The results underscore the importance of specific design features for preventing falls among older adults. A proper fit, secure fixation, appropriate heel and collar heights, slip resistance, and sole/insole hardness significantly contributed to fall prevention. These findings offer valuable guidance for optimizing footwear designs to enhance comfort, stability, and safety in the daily lives of older individuals. CONCLUSION: This comprehensive review fills a critical knowledge gap regarding the safety of footwear designs for fall prevention in older adults. The identified design features play a vital role in reducing the risk of falls and offer practical recommendations for the development of safer footwear. Ultimately, this study contributes to the existing knowledge base and supports efforts to prevent STFs in older adults through improved footwear design.

Contaminant film thickness affects walkway friction measurements.

Walkway tribometers are used to measure available friction for evaluating walkway safety and pedestrian slip risk. Numerous variables can affect tribometer measurements, including the type and distribution of contaminants on the surface. Here, we quantified the effect of application method on contaminant film thickness, and the effect of film thickness on tribometer measurements on the four reference walkway surfaces used in ASTM F2508-16e. Distilled water, 0.05% sodium lauryl sulfate (SLS) solution, and 0.04% Triton X-100 solution were poured, squirted, and sprayed onto the surfaces to quantify their naturally occurring film thicknesses. These application methods had a significant effect on the resulting film thickness (p < 0.038), with the pour method consistently generating the thickest films and the spray method generating the thinnest films. We then quantified the effect of film thickness for the three contaminants (thickness range 0.3-3.3 mm) on the friction measurements of three common tribometers (Mark IIIB, English XL, and BOT 3000E) on each reference surface. A separate ANOVA was used for each of the 3 × 4 × 3 = 36 combinations of tribometer, surface, and contaminant. Friction measured with the Mark IIIB decreased with increasing film thickness on one surface across all three contaminants and on a second surface with the SLS contaminant. Friction measured with the BOT 3000E was sensitive to film thickness on two surfaces with water and one surface with Triton. The XL was unaffected by contaminant film thickness. Overall, despite significant differences in film thickness with contaminant application method, friction measurements were either insensitive to film thickness or varied only a small amount in all cases except for the Mark IIIB on the roughest surface. Film thickness did not alter the relative slip resistance of the four ASTM F2508 reference surfaces.

The effect of wear on slip-resistance of winter footwear with composite outsoles: A pilot study.

Falls on icy surfaces are among the top causes of injuries for workers exposed to the outdoor environment. Our recent field study showed that a new generation of winter footwear incorporating composite outsoles was able to reduce slips and falls on icy surfaces by 68% and 78%, respectively. The widespread adoption of this type of footwear may lead to substantial reductions in pain, suffering and costs of fall-related injuries. However, these composite materials are sensitive to wear and abrasion, which makes it likely that their slip-resistance performance may degrade with use. The goal of this pilot study was to determine the extent to which the slip-resistance of two types of winter footwear with composite outsoles changed as they wore down with real-world use. Seven participants were recruited for this study and were asked to walk 100K steps with their assigned footwear. Tread depth and slip-resistance performance (using the Maximum Achievable Angle test) were measured at baseline and again after each 25K-step interval up to 100K. Our results showed that the slip-resistance performance of the test footwear dropped significantly after the 75K and 100K step intervals compared to baseline. In addition, significant changes in tread depth were found after only 25K steps. These findings indicate that the performance of this type of footwear degrades relatively quickly with real-world use. Therefore, larger scale study of the slip-resistance of winter footwear with composite outsoles is needed and members of the public should be made aware of the potential loss of slip-resistance of these products.

What Makes a Floor Slippery? A Brief Experimental Study of Ceramic Tiles Slip Resistance Depending on Their Properties and Surface Conditions.

The safety of the use of construction facilities should be a priority in today's busy world, where it is not difficult to get involved in an accident. Most of them, due to the pace at which we live today, are caused by slips, trips, and falls. This work presents a detailed analysis of the resistance of ceramic floors to these events, taking into account the surface properties and conditions (dry/wet), which, as presented, have a significant impact on the final slip resistance values. This study also investigates the relationship between surface roughness and anti-slip properties. According to the obtained results, it can be concluded that the surface roughness is not the main determinant of slip resistance, and the final value of it is influenced by many components that should be considered together and not be neglected when designing the surface finish. Furthermore, based on experimental measurements, it can be noted that the highest slip resistance in both wet and dry conditions showed the unglazed tiles with lapatto finish and the glazed tiles without any extra finish.

Comparative Analysis of Slip Resistance Test Methods for Granite Floors.

This paper attempts to compare three methods of testing floor slip resistance and the resulting classifications. Polished, flamed, brushed, and grained granite slabs were tested. The acceptance angle values (αob) obtained through the shod ramp test, slip resistance value (SRV), and sliding friction coefficient (µ) were compared in terms of the correlation between the series, the precision of each method, and the classification results assigned to each of the three obtained indices. It was found that the evaluation of a product for slip resistance was strongly related to the test method used and the resulting classification method. This influence was particularly pronounced for low roughness slabs. This would result in risks associated with inadequate assessments, which could affect the safe use of buildings facilities.

Evaluation of Winter Footwear: Comparison of Test Methods to Determine Footwear Slip Resistance on Ice Surfaces.

The use of slip-resistant winter footwear is crucial for the prevention of slips and falls on ice and snow. The main objective of this paper is to evaluate a mechanical testing method to determine footwear slip resistance on wet and dry ice surfaces and to compare it with the human-centred test method introduced by researchers at KITE (Knowledge, Innovation, Talent, Everywhere)-Toronto Rehabilitation Institute-University Health Network. Phase 1 of this study assessed the repeatability and reproducibility of the mechanical method by evaluating ten different occupational winter boots using two SATRA Slip resistance testers (STM 603, SATRA Technology Centre, Kettering, UK). One tester is located in Toronto and one in Montreal. These boots were chosen based on the needs of the IRSST (Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail, Montréal, Quebec, Canada), who were primarily interested in providing safe winter footwear for police, firefighters and municipal workers. In Phase 2, the results of the human-centred test approach were compared with the mechanical results. In Phase 3, two of these boots with conflicting results from the previous phases were tested using a second human-centred method. In Phase 1, the mechanical testing results obtained in the two labs showed a high linear correlation (>0.94) and good agreement on both ice surfaces; however, they revealed a bias (~0.06) between the two labs on the dry ice condition. The mechanical and human-centred tests (phase 2) were found to be better correlated in the wet ice condition (R = 0.95) compared to the dry ice condition (R = 0.34). Finally, the rating of the footwear slip resistance based on the number of slips counted in phase 3 was consistent with the rating by the human-centred test method (phase 2), but not the mechanical method (phase 1). The findings of this study provide a better understanding of the limitations of the SATRA ice tray for measuring footwear slip resistance and demonstrate that the mechanical method must be further refined to make it more comparable to the human-centred methods to achieve better agreement with real-world performance.

Reducing fall risk for home care workers with slip resistant winter footwear.

Falls on icy surfaces are the leading cause of occupational injuries for workers exposed to outdoor winter conditions. Slip resistant footwear has been shown to reduce the risk of falls for indoor workers but until recently, there was no accepted standard for evaluating the slip resistance of winter footwear on icy surfaces. Our team recently developed a lab-based testing protocol for measuring footwear slip resistance. This protocol, called the Maximum Achievable Angle (MAA) test, measures the steepest ice-covered slope that participants can walk up and down without experiencing a slip in a simulated winter environment. This lab-based protocol has found there is wide variability in the performance of commercially available winter footwear. In particular, we have found that a new generation of footwear that incorporates composite materials in the outsole, performs much better than most other footwear. The objective of this project was to investigate whether the footwear that performed well in our lab-based testing would reduce the risk of slips and/or falls in real-world winter conditions. One hundred and ten home healthcare workers from SE Health were recruited for this study and were asked to report their exposure to icy surfaces along with the numbers of slips and numbers of falls they experienced each week using online surveys over eight weeks in the winter. Fifty participants (the intervention group) were provided winter footwear that were among the best performing in the MAA test. The remaining sixty participants (the control group) wore their own footwear for the duration of the study. A total of 563 slips and 36 falls were reported over the eight-week data collection period. The intervention group consistently reported fewer slips (127 vs 436) and fewer falls (6 vs 30) compared to the control group. We found the slip rate in the intervention group was between 68.0% and 68.7% lower than the control group. Similarly, the fall rate was between 78.5% and 81.5% lower in the intervention group compared to the control group. These findings demonstrate that footwear that performs well in the MAA test can reduce the risk of both slips and falls in real-world winter conditions.

Quantifying the uncertainty in tribometer measurements on walkway surfaces.

Properly estimating and reporting the uncertainty of walkway surface friction is key to ensuring pedestrian safety. Here we quantified the amount and sources of uncertainty in friction measurements by having four users of four units of each of two walkway tribometer models (Slip-Test Mark IIIB, English XL) perform 12 measurements on four samples of four different surfaces that ranged from slippery to slip-resistant. We found that 51-82% of the total variance in the measurements was explained by the user, unit, sample and a user-unit interaction, which means that the variance a single user calculates from their own data does not capture most of the uncertainty in their measurements. Based on these data, the minimum uncertainty associated with the mean of a user's measurements is ±0.064 (Mark IIIB) and ±0.072 (XL) to be 95% confident that their mean captures a surface's available friction. Practitioner Summary: Walkway surface friction measurements are less accurate than they appear. Based on an experiment quantifying the amount and sources of uncertainty in surface friction measurements using two common tribometers, we quantified and report the minimum uncertainty that users can assign to their walkway surface friction measurements. Abbreviations: ANOVA: analysis of variance; ANSI: American National Standards Institute; CI: confidence interval; E: east; ILS: interlaboratory study; ISO: International Standards Organization; JCGM: joint committee for guides in metrology; N: north; S: south; SBR: styrene-butadiene rubber; SD: standard deviation; TR: test result; W: west.

Climbers' Perception of Hold Surface Properties: Roughness Versus Slip Resistance.

The more experienced a climber is, the more friction they can impart on a climbing hold surface. The aim of this research was to investigate how the properties of a hold's surface are perceived and how the perception relates to the amount of friction applied to the hold. The holds' surface properties are roughness/smoothness and grippiness/slippiness. Fourteen different surfaces with a wide range of property combinations were selected and placed on an instrumented climbing hold, mounted on a bouldering wall, and incorporated into a climbing route. Twenty-two climbers participated in the study. The ratio of friction to normal force (denoted friction coefficient or COF subsequently) was obtained from the sensor data, and the subjective ranking of the surface properties was provided by the participants. The average COF applied to the surfaces ranged from 0.53 (Teflon) to 0.84 (rubber). The surfaces with the lowest and highest grippiness and roughness ranking were Teflon and sandpaper, respectively. The correlation between roughness and COF was insignificant, whereas the correlation of grippiness and COF was significant. This applies to the 22 participants at the group level. At the individual level, 50% (11 climbers) of the participants did not show any correlations between surface properties and COF; eight climbers exhibited correlations between the combined grippiness and roughness (multiple regression) and COF, as well as grippiness and COF; only one climber out of the eight showed an additional correlation between roughness and COF. The results are interpreted in a way that climbers assess a hold's surface based on grippiness, and not on the roughness, and apply a COF to the hold that reflects the perception of grippiness.

Predicting slips based on the STM 603 whole-footwear tribometer under different coefficient of friction testing conditions.

Assessing footwear slip-resistance is critical to preventing slip and fall accidents. The STM 603 (SATRA Technology) is commonly used to assess footwear friction but its ability to predict human slips while walking is unclear. This study assessed this apparatus' ability to predict slips across footwear designs and to determine if modifying the test parameters alters predictions. The available coefficient of friction (ACOF) was measured with the device for nine different footwear designs using 12 testing conditions with varying vertical force, speed and shoe angle. The occurrence of slipping and the required coefficient of friction was quantified from human gait data including 124 exposures to liquid contaminants. ACOF values varied across the test conditions leading to different slip prediction models. Generally, a steeper shoe angle (13°) and higher vertical forces (400 or 500 N) modestly improved predictions of slipping. This study can potentially guide improvements in predictive test conditions for this device. Practitioner Summary: Frictional measures by the STM603 (SATRA Technology) were able to predict human slips under liquid contaminant conditions. Test parameters did have an influence on the measurements. An increased shoe-floor testing angle resulted in better slip predictions than test methods specified in the ASTM F2913 standard.

Robotic Cell Rotation Based on Optimal Poking Direction.

It is essential to have three-dimensional orientation of cells under a microscope for biological manipulation. Conventional manual cell manipulation is highly dependent on the operator's experience. It has some problems of low repeatability, low efficiency, and contamination. The current popular robotic method uses an injection micropipette to rotate cells. However, the optimal poking direction of the injection micropipette has not been established. In this paper, a strategy of robotic cell rotation based on optimal poking direction is proposed to move the specific structure of the cell to the desired orientation. First, analysis of the force applied to the cell during rotation was done to find the optimal poking direction, where we had the biggest moment of force. Then, the moving trajectory of the injection micropipette was designed to exert rotation force based on optimal poking direction. Finally, the strategy was applied to oocyte rotation in nuclear transfer. Experimental results show that the average completion time was up to 23.6 s and the success rate was 93.3% when the moving speed of the injection micropipette was 100 µm/s, which demonstrates that our strategy could overcome slippage effectively and with high efficiency.

Investigation of Floor Surface Finishes for Optimal Slip Resistance Performance.

BACKGROUND: Increasing the slip resistance of floor surfaces would be desirable, but there is a lack of evidence on whether traction properties are linearly correlated with the topographic features of the floor surfaces or what scales of surface roughness are required to effectively control the slipperiness of floors. OBJECTIVE: This study expands on earlier findings on the effects of floor surface finishes against slip resistance performance and determines the operative ranges of floor surface roughness for optimal slip resistance controls under different risk levels of walking environments. METHODS: Dynamic friction tests were conducted among three shoes and nine floor specimens under wet and oily environments and compared with a soapy environment. RESULTS: The test results showed the significant effects of floor surface roughness on slip resistance performance against all the lubricated environments. Compared with the floor-type effect, the shoe-type effect on slip resistance performance was insignificant against the highly polluted environments. The study outcomes also indicated that the oily environment required rougher surface finishes than the wet and soapy ones in their lower boundary ranges of floor surface roughness. CONCLUSION: The results of this study with previous findings confirm that floor surface finishes require different levels of surface coarseness for different types of environmental conditions to effectively manage slippery walking environments. Collected data on operative ranges of floor surface roughness seem to be a valuable tool to develop practical design information and standards for floor surface finishes to efficiently prevent pedestrian fall incidents.

Investigation of Floor Surface Finishes for Optimal Slip Resistance Performance

BACKGROUND: Increasing the slip resistance of floor surfaces would be desirable, but there is a lack of evidence on whether traction properties are linearly correlated with the topographic features of the floor surfaces or what scales of surface roughness are required to effectively control the slipperiness of floors. OBJECTIVE: This study expands on earlier findings on the effects of floor surface finishes against slip resistance performance and determines the operative ranges of floor surface roughness for optimal slip resistance controls under different risk levels of walking environments. METHODS: Dynamic friction tests were conducted among three shoes and nine floor specimens under wet and oily environments and compared with a soapy environment. RESULTS: The test results showed the significant effects of floor surface roughness on slip resistance performance against all the lubricated environments. Compared with the floor-type effect, the shoe-type effect on slip resistance performance was insignificant against the highly polluted environments. The study outcomes also indicated that the oily environment required rougher surface finishes than the wet and soapy ones in their lower boundary ranges of floor surface roughness. CONCLUSION: The results of this study with previous findings confirm that floor surface finishes require different levels of surface coarseness for different types of environmental conditions to effectively manage slippery walking environments. Collected data on operative ranges of floor surface roughness seem to be a valuable tool to develop practical design information and standards for floor surface finishes to efficiently prevent pedestrian fall incidents.

The slip extrusion test: A novel method to characterise bolus properties.

The role of mastication is to prepare a bolus for safe swallowing. The Swallow Safe model defines deformability, slippiness, and cohesiveness as key properties that influence whether a bolus is safe to swallow. Defining these properties numerically is difficult and current instruments used for bolus analysis have limitations. The slip extrusion test (SET) was developed to objectively measure the swallowability of the bolus through determination of its resistance to deformation and slip. The test measures the force needed to extrude a bolus through a bag as it is pulled through a pair of rollers, imitating the swallowing action of a bolus. Three food model systems were used to evaluate the SET: (a) viscous solutions with varying viscosity, (b) gels with varying hardness, and (c) particulate systems of varying cohesion. The test was applied to peanut boluses produced in vivo to demonstrate its potential in characterizing boluses. The deformation and slip resistance measurements correlated well with the hardness and viscosity measurements of the gels and viscous solutions respectively (correlation coefficient r = .94 between deformation resistance and hardness; r = .85 for slip resistance and hardness in gels; r = .98 for deformation resistance and viscosity; r = .93 for slip resistance and viscosity in solutions). The advantage of the SET is it can evaluate the swallowability of a wide range of foods of different structure and composition. It could potentially be used to investigate the properties of boluses throughout oral processing and help in establishing the criteria for a safe to swallow bolus in a quantitative way. PRACTICAL APPLICATIONS: The test could be used to measure bolus properties from the initial stages of breakdown to the point of swallow for all types of food. The ability to measure the changes in bolus properties through all stages of breakdown using the same instrument is a significant development. The resistance to deformation and slip are quantitative measurements that could potentially be used to further develop the Swallow Safe model by providing numerical limits to the identified properties. This could be of interest to the development of foods for dysphagia sufferers.

Multifunctional Textured Surfaces with Enhanced Friction and Hydrophobic Behaviors Produced by Fiber Debonding and Pullout.

Fiber debonding and pullout are well-understood processes that occur during damage and failure events in composite materials. In this study, we show how these mechanisms, under controlled conditions, can be used to produce multifunctional textured surfaces. A two-step process consisting of (1) achieving longitudinal fiber alignment followed by (2) cutting, rearranging, and joining is used to produce the textured surfaces. This process employs common composite manufacturing techniques and uses no reactive chemicals or wet handling, making it suitable for scalability. This uniform textured surface is due to the fiber debonding and pullout occurring during the cutting process. Using well-established fracture mechanics principles for composite materials, we demonstrate how different material parameters such as fiber geometry, fiber and matrix stiffness and strength, and interface behavior can be used to achieve multifunctional textured surfaces. The resulting textured surfaces show very high friction coefficients on wet ice (9× improvement), indicating their promising potential as materials for ice traction/tribology. Furthermore, the texturing enhances the surface's hydrophobicity as indicated by an increase in the contact angle of water by 30%. The substantial improvements to surface tribology and hydrophobicity make fiber debonding and pullout an effective, simple, and scalable method of producing multifunctional textured surfaces.

Slipping on pedestrian surfaces: methods for measuring and evaluating the slip resistance.

Tripping, slipping and falling accidents are among the types of accident with a high incidence. This article describes the requirements concerning slip resistance, as well as the state of the art of slip resistance measurement standards in the European Community and the USA. The article also describes how risk assessment can be performed in the field.

Assessing the performance of winter footwear using a new maximum achievable incline method.

More informative tests of winter footwear performance are required in order to identify footwear that will prevent injurious slips and falls on icy conditions. In this study, eight participants tested four styles of winter boots on smooth wet ice. The surface was progressively tilted to create increasing longitudinal and cross-slopes until participants could no longer continue standing or walking. Maximum achievable incline angles provided consistent measures of footwear slip resistance and demonstrated better resolution than mechanical tests. One footwear outsole material and tread combination outperformed the others on wet ice allowing participants to successfully walk on steep longitudinal slopes of 17.5° ± 1.9° (mean ± SD). By further exploiting the methodology to include additional surfaces and contaminants, such tests could be used to optimize tread designs and materials that are ideal for reducing the risk of slips and falls.

Comparison of Three Different Slip Meters under Various Contaminated Conditions.

OBJECTIVES: To challenge the problem of slipperiness, various slipmeters have been developed to assess slip hazard. The performance of in-situ slipmeter is, however, still unclear under the various floor conditions. The main objectives of this study were to evaluate the performance of three kinds of slipmeters under real conditions, and to find their dynamic and kinematic characteristics, which were compared with gait test results. METHODS: Four common restaurant floor materials were tested under five contaminants. Slipmeters and human gaits were measured by high speed camera and force plate to find and compare their dynamic and kinematic characteristics. RESULTS: The contact pressures and built-up ratio were below those of subjects. The sliding velocity of British Pendulum Tester was above those of subjects, while those of BOT-3000 and English XL were below those of subjects. From the three meters, the English XL showed the highest overall correlation coefficient (r = 0.964) between slip index and R(a), while the rest did not show statistical significance with surface roughness parameters (R(a), R(z)). The English XL only showed statistical significance (p < 0.01) between slip index and contaminants. The static coefficient of friction obtained with the BOT-3000 showed good consistency and repeatability (CV < 0.1) as compared to the results for the BPT (CV > 0.2) and English XL (CV < 0.2). CONCLUSION: It is unclear whether surface roughness can be a reliable and objective indicator of the friction coefficient under real floor conditions, and the viscosity of contaminants can affect the friction coefficient of the same floors. Therefore, to evaluate slipperiness, the performance of the slipmeters needed to improve.

Comparison of Three Different Slip Meters under Various Contaminated Conditions

OBJECTIVES: To challenge the problem of slipperiness, various slipmeters have been developed to assess slip hazard. The performance of in-situ slipmeter is, however, still unclear under the various floor conditions. The main objectives of this study were to evaluate the performance of three kinds of slipmeters under real conditions, and to find their dynamic and kinematic characteristics, which were compared with gait test results. METHODS: Four common restaurant floor materials were tested under five contaminants. Slipmeters and human gaits were measured by high speed camera and force plate to find and compare their dynamic and kinematic characteristics. RESULTS: The contact pressures and built-up ratio were below those of subjects. The sliding velocity of British Pendulum Tester was above those of subjects, while those of BOT-3000 and English XL were below those of subjects. From the three meters, the English XL showed the highest overall correlation coefficient (r = 0.964) between slip index and Ra, while the rest did not show statistical significance with surface roughness parameters (Ra, Rz). The English XL only showed statistical significance (p 0.2) and English XL (CV < 0.2). CONCLUSION: It is unclear whether surface roughness can be a reliable and objective indicator of the friction coefficient under real floor conditions, and the viscosity of contaminants can affect the friction coefficient of the same floors. Therefore, to evaluate slipperiness, the performance of the slipmeters needed to improve.