An Investigation of Structure, Flexibility, and Function Variables that Discriminate Asymptomatic Foot Types
in Journal of Applied BiomechanicsClick name to view affiliation
It has been suggested that foot type considers not only foot structure (high, normal, low arch), but also function (overpronation, normal, oversupination) and flexibility (reduced, normal, excessive). Therefore, this study used canonical regression analyses to assess which variables of foot structure, function, and flexibility can accurately discriminate between clinical foot type classifications. The feet of 61 asymptomatic, healthy adults (18–77 years) were classified as cavus (N = 24), rectus (N = 54), or planus (N = 44) using standard clinical measures. Custom jigs assessed foot structure and flexibility. Foot function was assessed using an emed-x plantar pressure measuring device. Canonical regression analyses were applied separately to extract essential structure, flexibility, and function variables. A third canonical regression analysis was performed on the extracted variables to identify a combined model. The initial combined model included 30 extracted variables; however 5 terminal variables (malleolar valgus index, arch height index while sitting, first metatarsophalangeal joint laxity while standing, pressure-time integral and maximum contact area of medial arch) were able to correctly predict 80.7% of foot types. These remaining variables focused on specific foot characteristics (hindfoot alignment, arch height, midfoot mechanics, Windlass mechanism) that could be essential to discriminating foot type.
Shultz is with the School of Sport and Exercise, Massey University, Wellington, New Zealand. Song is with Gait Study Center, Temple University School of Podiatric Medicine, Philadelphia, PA, USA. Kraszewski, Backus, and H.J. Hillstrom are with Leon Root M.D. Motion Analysis Laboratory, Hospital for Special Surgery, New York, NY, USA. Hafer is with Leon Root M.D. Motion Analysis Laboratory, Hospital for Special Surgery, New York, NY, USA; and the Department of Kinesiology, University of Massachusetts Amherst, Amherst, MA, USA. Rao is with Leon Root M.D. Motion Analysis Laboratory, Hospital for Special Surgery, New York, NY, USA; and the Department of Physical Therapy, New York University, New York, NY, USA. R.M. Hillstrom is with Leon Root M.D. Motion Analysis Laboratory, Hospital for Special Surgery, New York, NY, USA; and Medical Engineering Research Group, Faculty of Science and Technology, Anglia Ruskin University, Chelmsford, Essex, UK.
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