Christian Cifuentes-De la Portilla1, Ricardo Larrainzar-Garijo2, Javier Bayod3. 1. Applied Mechanics and Bioengineering Group (AMB), Aragón Institute of Engineering Research (I3A), Universidad de Zaragoza, Spain; Facultad de Ciencias Médicas - Departamento de Medicina, Universidad Espíritu Santo, Ecuador. Electronic address: cjcifuentesd@unal.edu.co. 2. Orthopaedics and Trauma Department, Surgery Department, Hospital Universitario Infanta Leonor, Madrid, Spain. 3. Applied Mechanics and Bioengineering Group (AMB), Aragón Institute of Engineering Research (I3A), Universidad de Zaragoza, Spain.
Abstract
BACKGROUND: Adult acquired flatfoot deformity (AAFD) is traditionally related to a tibialis posterior tendon deficiency. In the intermediate stages, treatments are commonly focused on reinforcing this tissue, but sometimes the deformation appears again over time, necessitating the use of more aggressive options. Tissue stress cannot be consistently evaluated through traditional experimental trials. Computational foot modeling extends knowledge of the disease and could help guide the clinical decisions. This study analyzes the biomechanical stress of the main tissues related to AAFD and their capacity to support the plantar arch. METHODS: A FE foot model was reconstructed. All the bones, cartilages and tissues related to AAFD were included, respecting their biomechanical characteristics. The biomechanical tissue stress was quantified. The capacity of each soft tissue to support the plantar arch was measured, following clinical criteria. FINDINGS: Biomechanical stress of the tibialis posterior tendon is considerably superior to both the plantar fascia and spring ligament stress. However, it cannot maintain the plantar arch by itself. Both the tibialis posterior tendon and spring ligament act in reducing the hindfoot pronation, while the plantar fascia is the main tissue that prevents arch elongation. The Achilles tendon action increases the plantar tissue stress. INTERPRETATION: The tibialis posterior tendon stress increases when the spring ligament or the fascia plantar fails. These findings are consistent with the theory that regards the tibialis posterior tendon as a secondary actor because it cannot support the plantar arch and claudicates when the hindfoot has rotated around the talonavicular joint.
BACKGROUND: Adult acquired flatfoot deformity (AAFD) is traditionally related to a tibialis posterior tendon deficiency. In the intermediate stages, treatments are commonly focused on reinforcing this tissue, but sometimes the deformation appears again over time, necessitating the use of more aggressive options. Tissue stress cannot be consistently evaluated through traditional experimental trials. Computational foot modeling extends knowledge of the disease and could help guide the clinical decisions. This study analyzes the biomechanical stress of the main tissues related to AAFD and their capacity to support the plantar arch. METHODS: A FE foot model was reconstructed. All the bones, cartilages and tissues related to AAFD were included, respecting their biomechanical characteristics. The biomechanical tissue stress was quantified. The capacity of each soft tissue to support the plantar arch was measured, following clinical criteria. FINDINGS: Biomechanical stress of the tibialis posterior tendon is considerably superior to both the plantar fascia and spring ligament stress. However, it cannot maintain the plantar arch by itself. Both the tibialis posterior tendon and spring ligament act in reducing the hindfoot pronation, while the plantar fascia is the main tissue that prevents arch elongation. The Achilles tendon action increases the plantar tissue stress. INTERPRETATION: The tibialis posterior tendon stress increases when the spring ligament or the fascia plantar fails. These findings are consistent with the theory that regards the tibialis posterior tendon as a secondary actor because it cannot support the plantar arch and claudicates when the hindfoot has rotated around the talonavicular joint.