Stride Tech Medical Inc. & Modena Cherry Creek

13 January 2021

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SUMMARY

• Incorrect walker use is associated with increased fall risk in older adults, but little is being done to address the issue.
• Transitional movements such as turning can be a vital indicator of mobility quality, with longer turning durations being an indicator of higher fall risk.
• Our product, the Stride Tech Go, measures the two most common methods of incorrect walker use: 

1. Excessive weight-bearing on the handles (measured as left- and right-hand force on the left and right hand handles)
2. Excessive distance between the user and the device (measured as distance between the user’s hip and the frame of the walker) 

• With StrideTech Go, we can use our hip distance measurements to determine 1. If someone is turning, 2. The duration of their turn and, 3. How much their hip distance deviates from their baseline during a turn
• With StrideTech Go, we can use our left- and right-hand force measurements to determine asymmetrical gait

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INTRODUCTION

Stride Tech Medical Inc.’s mission is to prevent falls. Seniors widely use walkers to maintain mobility while reducing the risk of falls. Despite the benefits, habitually poor walker use, marked by excessive weight-bearing on the walker handles and/or excessive distance between the user and the walker, can lead to muscle atrophy, poor posture, and falls. A widely publicized investigation in 2009 showed over 87% of severe falls with an assistive device occurred with a walker. They recommended increased time devoted to fitting and education on proper use. Eleven years later, most seniors still do not receive individualized fitting or training on how to use their walkers.

Our product, the StrideTech Go , is an attachable walker accessory which integrates sensors and biofeedback onto existing walkers to correct common misuses in real time. Grip covers are embedded with and sensors Velcro over the handles of a walker. An additional sensor is mounted to the frame which measures the user’s hip distance from the frame. The grip covers vibrate if the sensors detect either of the two primary indicators of walker misuse:

• Excessive weight load through the handles
• Excessive distance between the frame of the walker and the use

StrideTech Go is the first commercial product to help fill the urgent need for long-term walker use training. This white paper will outline the technical background and testing done to establish efficacy and briefly outline next steps and improvements. 

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PROTOCOL

StrideTech defines short term efficacy as the ability to see changes in StrideTech Go measures of walker use in a single product testing session. The data presented was collected from a walker repair event held at a local senior living facility. The user was asked to complete a baseline in which they walked a figure eight shape the length of the testing room. They repeated the figure eight walk three times. The user was NOT given StrideTech Go feedback. 

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This baseline data is crucial, as it allows StrideTech to assess the range of weight and hip distances measured across different older adults for both straight line walking and predetermined transitional movements, like left- and right-hand turns. This in turn reaffirms the sensors have the adequate range and sensitivity for this population. 

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Additionally, the entirety of the baseline walk was filmed. The timing and direction of each turn taken by the user to switch walking directions was recorded. The user was guided by taped arrow markings outlining the figure eight path. 

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RESULTS

Above is a graph of the hip distance (in inches) against time (in seconds) of the baseline (gray, circular markers) and feedback (green, square marker) trials. This user was able to complete three total figure eight walks for their baseline trial, and one total figure eight walk for their feedback trial. (The user became too fatigued to continue the feedback test.)  

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Several aspects of the baseline vs. feedback trials are evident. First, the total duration of the two trials is dramatically different. The baseline trial, which consisted of three total figure eight loops, had a total duration of 4 minutes and 6 seconds. The feedback trial, which consisted only of one total figure eight loop, had a total duration of 5 minutes and 32 seconds. The increased duration in the feedback trial is immediately seen in the video. Each time the device triggers vibration feedback, the user stops walking, pulls their walker in closer to their body until the vibration ceases, then continues to walk. The increased duration for a shorter task could be an indication of learning or an added cognitive load as the user must process, then respond to, the feedback while walking. 

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Second, the variance in the hip distance data is dramatically different. Visually, the baseline hip distance is relatively consistent. The average hip distance is 21.0 inches, with a range of 7 inches. The average feedback hip distance, while lower at 14.6 inches, had a total range of 18 inches across the trial. The baseline hip distance had a standard deviation of 1.2 inches, while the feedback hip distance had a standard deviation of 3.4 inches. Visually and mathematically, this results in hip distances that are much more variable in feedback trials when compared to baseline trials. This is resultant from the effort required to respond to the vibrational feedback the user frequently received.

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This short test encourages promising results. Not only did the user demonstrate an almost seven-inch decrease in hip distance due to feedback, but the increased variance could also be an indicator of an initial learning phase, as he learned how to respond to the feedback.¹

User 3 additionally reduced handle loading in feedback trials. In the latter half of the feedback trial, User 3 reduces force through his left (dark blue) and right (dark orange) hands. The average left-hand force was reduced from 11.9 lbf, with a 3.1 standard deviation, in baseline trials to 7.4 lbf, with a 1.9 standard deviation, in feedback trials. The average right-hand force was reduced from 6.6 lbf, with a 1.1 standard deviation, to 4.1 lbf, with a 2.2 standard deviation, in feedback trials. The cycles of learning are not as clear as in the instances of hip distance feedback. We theorize this was due to the user’s inability to discern between the forms of feedback specific to each type of walker misuse (for weight-bearing feedback, the handles vibrate constantly; for hip distance feedback, the handles vibrate cyclically). Additionally, the user expressed more intent in learning to keep his walker closer to him, which may have resulted in less focus on adjusting the weight he placed on his walker through his hands. 

These case studies are a highlight of the incredible efficacy and opportunity StrideTech Go offers. The potential confusion in feedback types may inhibit users from fully learning to correct both types of walker misuse at the same time, and careful consideration must be afforded to the possibility users may need to choose which type of walker misuse they wish to address first, or the possibility that once one type is mastered, the other may be introduced. The ability to effectively improve walker use and track learning/compliance over time is vital to walker safety and fall prevention. Users can improve walker use in a short duration, and PTs can track the consistency of improvement over time. 

FUTURE WORK 

More data and more testing are needed to explore the exciting potential of the Stride Tech Go. Future work will call for longer testing sessions (to determine if increased training time results in decreased variability) and testing over multiple days (to assess if improvements are retained after a single session).   

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^1. _{Lawrence GP, Gottwald VM, Khan MA, Kramer RS. The Movement Kinematics and Learning Strategies Associated with Adopting Different Foci of Attention during Both Acquisition and Anxious Performance. Front Psychol. 2012 Nov 2;3:468. doi: 10.3389/fpsyg.2012.00468. PMID: 23130008; PMCID: PMC3487420.}