title: Finite element analysis of plantar fascia during walking: a quasi-static simulation.
abstract: BACKGROUND
  The plantar fascia is a primary arch supporting structure of the foot and is often stressed with high tension during ambulation. When the loading on the plantar fascia exceeds its capacity, the inflammatory reaction known as plantar fasciitis may occur. Mechanical overload has been identified as the primary causative factor of plantar fasciitis. However, a knowledge gap exists between how the internal mechanical responses of the plantar fascia react to simple daily activities. Therefore, this study investigated the biomechanical responses of the plantar fascia during loaded stance phase by use of the finite element (FE) modeling.
  
  
  METHODS
  A 3-dimensional (3-D) FE foot model comprising bones, cartilage, ligaments, and a complex-shaped plantar fascia was constructed. During the stance phase, the kinematics of the foot movement was reproduced and Achilles tendon force was applied to the insertion site on the calcaneus. All the calculations were made on a single healthy subject.
  
  
  RESULTS
  The results indicated that the plantar fascia underwent peak tension at preswing (83.3% of the stance phase) at approximately 493 N (0.7 body weight). Stress concentrated near the medial calcaneal tubercle. The peak von Mises stress of the fascia increased 2.3 times between the midstance and preswing. The fascia tension increased 66% because of the windlass mechanism.
  
  
  CONCLUSIONS
  Because of the membrane element used in the ligament tissue, this FE model was able to simulate the mechanical structure of the foot. After prescribing kinematics of the distal tibia, the proposed model indicated the internal fascia was stressed in response to the loaded stance phase.
  
  
  CONCLUSIONS
  Based on the findings of this study, adjustment of gait pattern to reduce heel rise and Achilles tendon force may lower the fascia loading and may further reduce pain in patients with plantar fasciitis.
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, Tainan City, Taiwan Metal Industries Research & Development Centre, Kaohsiung City, Taiwan.
authors.forename: Yen-Nien
authors.initials: YN
authors.lastname: Chen
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, Tainan City, Taiwan Department of Orthopedics, National Cheng Kung University Hospital, Tainan City, Taiwan.
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Chang
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, Tainan City, Taiwan.
authors.forename: Chun-Ting
authors.initials: CT
authors.lastname: Li
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, Tainan City, Taiwan.
authors.forename: Chih-Han
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Department of Physical Therapy, National Cheng Kung University, Tainan City, Taiwan connie@mail.ncku.edu.tw.
authors.forename: Cheng-Feng
authors.initials: CF
authors.lastname: Lin
mesh_terms: D000328:Adult; D005205:Fascia / Q000502:physiology*; D036981:Fasciitis, Plantar / Q000503:physiopathology / Q000517:prevention & control; D020342:Finite Element Analysis; D005528:Foot / Q000502:physiology*; D006801:Humans; D008953:Models, Anatomic; D013314:Stress, Mechanical; D016138:Walking / Q000502:physiology*
keywords: finite element (FE) model; foot arch; gait simulation; plantar fascia