Research Article: Objective measures of rollator user stability and device loading during different walking scenarios

Date Published: January 30, 2019

Publisher: Public Library of Science

Author(s): Eleonora Costamagna, Sibylle B. Thies, Laurence P. J. Kenney, David Howard, Ulrich Lindemann, Jochen Klenk, Rose Baker, Heidi H. EWEN.


Walking aids are widely used by older adults, however, alarmingly, their use has been linked to increased falls-risk, yet clinicians have no objective way of assessing user stability. This work aims to demonstrate the application of a novel methodology to investigate how the type of walking task, the amount of body weight supported by the device (i.e., device loading), and task performance strategy affect stability of rollator users. In this context, ten users performed six walking tasks with an instrumented rollator. The combined stability margin “SM” was calculated, which considers user and rollator as a combined system. A Friedman Test was used to investigate the effects of task on SM and a least-squares regression model was applied to investigate the relationship between device loading and SM. In addition, the effects of task performance strategy on SM were explored. As a result, it was found that: the minimum SM for straight line walking was higher than for more complex tasks (p<0.05); an increase in device loading was associated with an increase in SM (p<0.05); stepping up a kerb with at least 1 rollator wheel in ground contact at all times resulted in higher SM than lifting all four wheels simultaneously. Hence, we conclude that training should not be limited to straight line walking but should include various everyday tasks. Within person, SM informs on which tasks need practicing, and which strategy facilitates stability, thereby enabling person-specific guidance/training. The relevance of this work lies in an increase in walking aid users, and the costs arising from fall-related injuries.

Partial Text

Falls and fall-related injuries among older people are a major health problem; around 40% of the over 65s living at home are estimated to fall at least once a year, with around one in forty of the falls leading to hospitalisation [1]. The incidence of falls and the severity of the consequences increase rapidly with age [1, 2], cost the NHS an estimated £2.3 billion per year [3], and have major social impacts on the individual and their families [4]. As the number of over 65s is due to double by 2050, without changes to falls prevention strategies, the number of fall-related injuries is also likely to increase.

All tasks were completed by all patients within a maximum of 20 minutes and without any obvious signs of fatigue (not tested).

This is the first study that, in a cohort of 10 in-patients in a geriatric ward, assessed stability with an instrumented rollator for six everyday walking tasks. Stability was investigated with an objective assessment methodology previously developed by the authors [10], which treats the user and their rollator as a single combined system and informs on the corresponding stability margin, i.e. how far the system is from the point of “tipping over”. It is noteworthy that since its initial development [10], the method has been further refined in that SMSystem is now normalized to take into account the size of the BoS, because a smaller SMSystem may simply be the consequence of a smaller BoS. However, despite this normalization, the sample data of two participants (one fit and one comparatively frail) indicate that, whilst SM is a direct measure of stability (nearness to tipping), a larger SM (as observed for the more frail user) does not necessarily mean a safer gait and lower risk of falling. For instance, those users who need a rollator only as a balance aid, and which do not transfer substantial amounts of body weight onto the device, will likely have a lower SM than those who need it for weight-bearing support. In future, a measure representative of overall stability that does not depend on absolute values of SM would be more informative, especially when it is the aim to characterize relative stability of participants.

In summary, our approach provides objective data on walking stability of the combined system (user and rollator) for a range of everyday tasks, and provides first insights into how to objectively assess alternative rollator use strategies to inform evidence-based training. The relevance of our approach lies in an increase in users of walking aids within our ageing population, and the associated costs arising from fall-related injuries. One key insight gained is that training should not be limited to straight line walking alone, but should include more complex tasks representative of daily walking activities. Within person, the stability margin SM can be used to identify which tasks needs to be practiced, and which strategy facilitates stable performance of a given task. Indeed, in principle, the use of instrumented rollators as assessment tools in clinics could enable person specific guidance and training. Longer-term, evidence-based training should increase the benefits of using rollators as a means of fall prevention.




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