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Design and Effect of Ankle-Foot Orthoses Proposed to Influence Muscle Tone: A Review

Kobayashi, Toshiki PhD; Leung, Aaron K.L. PhD; Hutchins, Stephen W. PhD

JPO: Journal of Prosthetics and Orthotics: April 2011 - Volume 23 - Issue 2 - p 52-57
doi: 10.1097/JPO.0b013e3182173a61
Article

Ankle-foot orthoses (AFOs) designed and proposed to influence muscle tone are generally called as “tone-reducing” AFOs, “tone-inhibiting” AFOs, or “dynamic” AFOs. These orthoses were originally evolved from the use of plaster casts to influence the positive support reflex or tonic reflex, which were either triggered by pressing reflexogenous areas on the plantar surface of the foot or suppressed by offloading them. The effects of wearing AFOs to influence muscle tone have mainly been studied in patients with cerebral palsy, stroke, or head injury. Although different AFO designs exist, it seems that there is a lack of evidence to demonstrate that these AFOs can actually reduce or inhibit spastic muscle tone. This article specifically reviews the classification of patient groups recruited in previous studies, the design characteristics of AFOs, and the clinical and biomechanical effects reported. The results of this review suggested that the level of evidence for AFOs being able to influence muscle tone was very low. Therefore, further research with randomized controlled trials is required to investigate their clinical effects.

Ankle-foot orthoses designed and proposed to influence muscle tone are generally called as “tone-reducing,” “tone-inhibiting” or “dynamic” AFOs (TRAFOs, TIAFOs or DAFOs). The effects of wearing AFOs to influence muscle tone have mainly been studied in patients with cerebral palsy, stroke or head injury. Although different AFO designs exist, it appears that there is lack of evidence to demonstrate that these AFOs can actually reduce or inhibit spastic muscle tone. This paper specifically reviews the classification of patient groups recruited in previous studies, the design characteristics of AFOs, and the clinical and biomechanical effects reported.

TOSHIKI KOBAYASHI, PhD, is affiliated with the Orthocare Innovations, Mountlake Terrace, Washington.

AARON K.L. LEUNG, PhD, is affiliated with the Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China.

STEPHEN W. HUTCHINS, PhD, is affiliated with the Centre for Health, Sport and Rehabilitation Sciences Research, University of Salford, Salford, United Kingdom.

Disclosure: The authors declare no conflict of interest.

This work was supported by The Hong Kong Polytechnic University International Postgraduate Scholarships for PhD studies.

Correspondence to: Toshiki Kobayashi, PhD, 6405 218th SW, Suite 301, Mountlake Terrace, WA 98043; e-mail: tkobayashi@orthocareinnovations.com.

© 2011 American Academy of Orthotists & Prosthetists