Evidence of concurrent validity between a portable force plate and an instrumented walkway when measuring limits of stability

Cal Johnson, SPT and Jessica Landry, SPT

DPT2018 LoS.pptx

17 Comments on “Evidence of concurrent validity between a portable force plate and an instrumented walkway when measuring limits of stability

  1. When using the Prokinetic Zeno Walkway, must there be special markings applied to match the 4 quadrants of the Bertec Force Plate when using it to measure Limits of Stability?

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    • If you are using the Zeno Walkway independently to measure Limits of Stability you would not need to apply any special markings. The system would measure your starting position and your furthest excursion points to determine those values. We only used markings to ensure that foot placement remained the same between the two devices. Thanks for the question!

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  2. I understand this was not the purpose of your study but do you see any significant benefits to one versus the other device given they both seem to be accurate?

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    • Accuracy is similar between the two but there are benefits to using each device. The Bertec is much smaller so it would be ideal for a small work environment or if you had to travel for a project. The Zeno Walkway is much larger but also measures gait. If you were planning to assess but static balance and gait deviations, this would be a better choice. Thanks for your question!

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  3. I was curious if in your research you came across the use of these tools for pre- and post-treatment for changes in balance? I was wondering if you did find this tool to be used for balance assessments, was one used more often and why? Lastly, did you find any research using either of these tools for participants who are not healthy or have known deficits in balance/LoS and the reliability/validity in those populations? Thanks!

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    • all excellent questions! unfortunately when we were looking for research on the bertec and zeno we were looking in its specific relation to limits of stability and glazed past a wealth of research on the tools’ uses. The bertec is a well established tool for measuring balance however the zeno is very new and this is some of the first research done to validate it. In terms of future research you were right on the money for where we hope to take the research in terms of finding out if the reliability holds true with impaired populations such as individuals with Parkinsons.

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  4. Great study and thank you for providing validity to allow options for assessment!
    I have two questions:
    1. You mention that these products can be used to help identify those at risk for falls by measuring LoS. Does any research you have seen suggest which factors are best predictors for predicting falls? For instance in your study you measured reaching in anterior, posterior, right, and left. Is one of these directions a better predictor for falls risk than another?
    2. This is a speculative question, but in your opinion and experience with these devices, can they be utilized to provide measures of dynamic balance and if so, do you believe that these products would still offer similar results?

    Thank you for your time and consideration

    Jon Gray

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  5. 1. We didn’t use a pathological population in our study, but I have found some articles that discuss limitations in posterior and posterior right/left directions of LOS in relation to individuals with MS. I’d have to look further into the details but you could extrapolate that the decreased limits in this direction would result in increased falls in a posterior direction due to the decreased BOS in that direction. I will include a link to an article that might explain it better. http://www.sciencedirect.com/science/article/pii/S1877065715000482
    2. This depends greatly on the definition of dynamic balance that you’re using. Dynamic postural stability is defined as a moving COM with a fixed BOS, whereas functional postural stability is controlling a moving COM with a changing BOS. In our study we looked at dynamic postural stability but functional stability would be the common balance thought of as dynamic. Functional balance would be difficult to measure with the Bertec based on the limited size of the balance board. You would not be able to take multiple steps to measure balance over distance. The ZenoWalkway was originally designed to measure gait but it would be difficult to compare the two systems in this setting.

    Cal might have additional thoughts on this.

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  6. Great job on your research! Your poster was very neat, organized, and easy to read. One question regarding the price of these devices. Since both devices provide reliable measurement for LoS, is one cheaper compared to the other?

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    • The between the software and the different specifications you can by the products in the price varies a lot. Because of this the companies traditionally have potential buys talk to a salesmen before giving an estimate. The university of South Dakota has the equipment on lease because it is so expensive.

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  7. I understand that your subjects were healthy young adults, but if this study were to be recreated with a more vulnerable population (i.e. balance impaired older adults), would there be any special considerations for the researcher to keep in mind when guarding for safety in order to avoid influencing the data?

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    • The current future we have in mind for furthering this research is to eventually collect data on patients with Parkinsons. Like with our normal trials when a patient employees a balance strategy outside of the ankle system we could classify it as a mistrial and start over. the only extra precaution we would need for patients with balance impairments is a physical therapist that is on stand by assist for when they do lose balance and need an outside assist to stabilize themselves.

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  8. My question does not relate to your results but rather your thoughts as researchers. Did you find that one device was more user friendly besides the portability aspect of the Bertec? And if so, what about that device made it easier to work with?

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    • This is a difficult question to answer as we were each operated only one of the devices throughout the data collection. We were able to complete participant testing and save the results in a similar amount of time so there was not a noticeable difference in the operation difficulty affecting timelines.

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  9. Great work guys! It was mentioned that both the Bertec BalanceCheck Force Plate and The Zeno Walkway were portable, I was wondering if this mobility would relate to the clinic and if you believe more clinicians will start to implement these pieces of equipment in their practices?

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    • Although the smaller size would make the Bertec easier to utilize at a clinic with limited space, I do not see the mobility factor largely affecting implementation at this point in time due to the high cost associated with the devices. They would be appropriate for conducting testing and retesting of balance impairments but many clinical situations do not require the high level of technical information that is provided by either device. Similar devices are currently in practice in clinical settings and these often include balance training modes that allow individuals to challenge their balance while monitoring their movements. As prices lower, hopefully these will become more and more available for clinical use but until then, they are great tools for research and can be tested again other testing measures such as the Berg Balance Test, FAB-Q, or MiniBEST.

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  10. Hey guys, great poster and sorry for the late post! I was just wondering if these two devices are used only as an assessment tool, or can you use them for intervention as well? In the clinic I’ve seen some other devices like the Biodex that you can use as an assessment and then for balance training as well. Since these are more expensive, I feel like a clinic might be more open to investing in one if you’d be able to also use it for training rather than just for assessments.

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