title: Simple finite element models for use in the design of therapeutic footwear.
abstract: Therapeutic footwear is frequently prescribed in cases of rheumatoid arthritis and diabetes to relieve or redistribute high plantar pressures in the region of the metatarsal heads. Few guidelines exist as to how these interventions should be designed and what effect such interventions actually have on the plantar pressure distribution. Finite element analysis has the potential to assist in the design process by refining a given intervention or identifying an optimal intervention without having to actually build and test each condition. However, complete and detailed foot models based on medical image segmentation have proven time consuming to build and computationally expensive to solve, hindering their utility in practice. Therefore, the goal of the current work was to determine if a simplified patient-specific model could be used to assist in the design of foot orthoses to reduce the plantar pressure in the metatarsal head region. The approach is illustrated by a case study of a diabetic patient experiencing high pressures and pain over the fifth metatarsal head. The simple foot model was initially calibrated by adjusting the individual loads on the metatarsals to approximate measured peak plantar pressure distributions in the barefoot condition to within 3%. This loading was used in various shod conditions to identify an effective orthosis. Model results for metatarsal pads were considerably higher than measured values but predictions for uniform surfaces were generally within 16% of measured values. The approach enabled virtual prototyping of the orthoses, identifying the most favorable approach to redistribute the patient's plantar pressures.
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Spirka
authors.affiliation: Computational Biomodeling (CoBi) Core and Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Erdemir
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Ewers Spaulding
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Yamane
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA; Institute of Applied Health Research, Glasgow Caledonian University, Glasgow, UK.
authors.forename: Scott
authors.initials: S
authors.lastname: Telfer
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA. Electronic address: cavanagh@uw.edu.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Cavanagh
mesh_terms: D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology; D020342:Finite Element Analysis; D005528:Foot / Q000503:physiopathology; D061826:Foot Orthoses; D006801:Humans; D008297:Male; D008682:Metatarsal Bones / Q000503:physiopathology; D008875:Middle Aged; D008954:Models, Biological; D010146:Pain / Q000503:physiopathology; D011312:Pressure; D012775:Shoes
keywords: Diabetes; Finite element method; Foot; Footwear; Model