By Greg Gargiulo
Ankle foot orthoses (AFOs) improve self-reported balance confidence and may also improve physical functioning in individuals with chronic poststroke hemiplegia, according to a study published in the April issue of Prosthetics and Orthotics International.
Self-efficacy, or the belief in one’s ability to succeed in particular situations, as it relates to falls may be an important aspect of balance, but this has not been studied relative to AFO use, according to Angelika Zissimopoulos, PhD.
Zissimopoulos and her fellow researchers at Northwestern University Prosthetics-Orthotics Center in Chicago assessed the effect of AFOs on self-efficacy for 15 individuals (8 women, mean age 55 years) with poststroke hemiplegia for a mean duration of 12 years. Participants were all currently wearing a variety of nonrigid polymer AFOs; articulated AFOs with a plantar flexion stop were the most common (60%).
All patients attended two sessions, one with and one without the AFO, in a randomized order for data collection. Forward walking speed was calculated using an eight-camera motion capture system with a marker placed over the patients’ sacrum while they walked back and forth.
After the gait speed assessment during each session, participants used the activities-specific balance confidence (ABC) scale to imagine 16 commonplace activities and estimate their confidence (from 0%-100%) in performing the activities without losing their balance or falling. Patients provided two sets of estimates, based on performing activities with and without AFOs.
The ABC Scale scores indicated that participants were significantly more confident in their balance with an AFO (68%) than without it (52%), and the change in walking speed from no AFO to AFO was positively associated with ABC scores.
In addition, the researchers classified the participants’ functional levels based on ABC score categories established in a 1998 study of older adults published in the Journals of Gerontology. In the Northwestern study, 27% of participants were classified as high functioning and 53% as moderate functioning with the AFO, compared with only 7% and 53%, respectively, without the AFO.
These findings suggest AFO use is associated with improved function in some hemiplegic stroke survivors, and this may be related to improved balance confidence.
The Northwestern investigators were not able to determine if these improvements were due to a particular gait parameter or a psychological effect of wearing the device. Also, due to the small sample size and variation in AFO type, they were not able to assess which type of AFO led to the greatest improvements. It’s also difficult to generalize these results to acute poststroke patients or other AFO types just yet, Zissimopoulos said.
“We’d really just like to work towards clarifying whether there is one type of AFO that’s better or if it is just the presence of the device,” she said. “If it’s not merely the presence, then what specific benefits is it providing, and can we identify a biomechanical difference that may explain why the confidence goes up?”
Alex Aruin, PhD, a professor of physical therapy at the University of Illinois at Chicago who has studied orthotic management of stroke patients, agreed that the current Northwestern findings should be considered preliminary.
“While the study provides information about the beneficial effect of AFOs on self-efficacy measured with the ABC scale, in my opinion, it could not be generalized to a large population of individuals with stroke, and I would consider the outcome with caution,” he said.
While some, including Aruin, still favor traditional measures for assessing balance, this first-of-its-kind study suggests that balance self-efficacy may be an alternative outcome measure worth investigating in future studies on poststroke balance.
“Now that we’ve actually demonstrated that a difference does exist, the next step is to figure out the ‘why,’” Zissimopoulos said.
She hopes to accomplish this by expanding to a larger sample size to further confirm these results, since they were based on a small initial group.
Zissimopoulos A, Fatone S, Gard S. The effect of ankle-foot orthoses on self-reported balance confidence in persons with chronic poststroke hemiplegia. Prosthet Orthot Int 2014;38(2):148-154.
Myers AM, Fletcher PC, Myers AH, et al. Discriminative and evaluative properties of the Activities-Specific Balance Confidence (ABC) Scale. J Gerontol A Biol Sci Med Sci 1998; 53(4):M287-M294.