Pilot Study: Evaluation of Ankle Foot Orthoses (AFOs)
using Roll-over Shapes

Steven Gard, PhD, Principal Investigator
Stefania Fatone, PhD, Project Director

Co-Investigators:
Dudley Childress, PhD; Andrew Hansen, PhD; and Rebecca Stine, MS, Northwestern University
Bryan Malas, CO, MHPE, Department of Orthotics, Children's Memorial Hospital

Funded by: National Institute on Disability and Rehabilitation Research (NIDRR)

Purpose

Ankle Foot Orthoses (AFOs) are among the most commonly prescribed categories of lower-limb orthoses, and they have proven to be effective clinically in enhancing the function of the ankle-foot complex (Bowker et al., 1993). Although thermoplastic AFOs are the most common type of orthosis in the U.S. today (Whiteside et al., 2000), objective functional analyses are limited. Because able-bodied subjects appear to use roll-over shape as a goal for the ankle-foot complex during walking, it seems that this may also be a logical objective for orthotic ankle-foot systems. Roll-over shape is defined as the geometry the ankle-foot complex effectively conforms to between initial contact and opposite initial contact (Hansen, 2000). Assessment of roll-over shapes provides information regarding the net functional effects of the foot, ankle-foot, and knee-ankle-foot systems and how well ‘normal’ walking is re-established. It is not yet understood what influence varying aspects of AFO design, such as magnitude of ankle motion, motion through different portions of the normal ankle joint range, and foot-plate length, may have on roll-over shape. We believe that roll-over shape principles may be used to evaluate the function of current AFO designs and the extent to which various designs of AFOs re-establish a more ‘normal’ walking pattern. The challenge in improving AFO design is to determine how to improve the walking pattern without compromising any other goals the orthosis may have. The purpose of this pilot study is to evaluate the walking performance of AFOs using roll-over shapes.

References

Whiteside, S.R., Alaimo, J., Barringer, W.J., Beiswenger, W.D., Bulgarelli, T., Hentges, C.J., Lin, R.S., Miller, T.E., Parr, R.G., Reynolds, J.H., Stills, M.L. (2000) Practice Analysis of the Disciplines of Orthotics and Prosthetics. Practice Analysis Task Force, American Board for Certification in Orthotics and Prosthetics, Inc.

Bowker, P., Condie, D.N., Bader, D.L., Pratt, D.J. (1993) Biomechanical Basis of Orthotic Management. Butterworth Heinemann, Oxford, UK.

Hansen, A. (2002) Roll-over Characteristics of Human Walking With Applications for Artificial Limbs. PhD Dissertation, Northwestern University, Evanston, IL.

Related Publications

Sorci E., Fatone S., Hansen A. and Gard S. (2007) Pilot Study Evaluating Ankle Foot Orthoses using Roll-over Shapes.  Annual Meeting and Scientific Symposium of the American Academy of Orthotists and Prosthetists, March 21-24, San Francisco, California.  (Resident Poster).