The potential influence of the heel counter on internal stress during static standing: A combined finite element and positional MRI investigation

Plantar pressure relief under the metatarsal heads – Therapeutic insole design using three-dimensional finite element model of the foot

“…Few assumptions were made to the model, including isotropic linear elastic material properties assigned to the ligaments and cartilages, isotropic hyperelastic model to the plantar tissue, simplified method to calculate muscle forces, and structural simplifications to intrinsic muscles and joint capsules. Similar assumptions have been made by other researchers (Gefen, 2002;Cheung and Zhang, 2005;Erdemir et al, 2005;Spears et al, 2007;Garcia-Gonzalez et al, 2009), which were deemed reasonable and necessary to limit modeling complexity. Lastly, our FE model was based on single-subject design.…”

The influence of foot posture, support stiffness, heel pad loading and tissue mechanical properties on biomechanical factors associated with a risk of heel ulceration

“…where µ is the long-term shear modulus, taken as 0.29 kPa for fat and 640 kPa for skin (Miller-Young et al, 2002;Spears et al, 2007); α is a dimensionless material parameter, taken as 8.8 for fat and 6.8 for skin (Miller-Young et al, 2002;Spears et al, 2007); k is the bulk modulus, calculated to be 28.9 kPa for fat and 63.8 MPa for skin given the aforementioned values of shear moduli and Poisson's ratio; λ i are principal stretch ratios and J = det(F) where F is the deformation gradient tensor. The long-term shear moduli of the aforementioned tissues were used under the assumption that the foot posture is maintained for a prolonged period, so that stress relaxation in the viscoelastic soft tissues is already in its plateau phase.…”

“…The load-bearing response of the heel was only studied in the context of standing, walking and running, e.g. in the FE analyses of Spears (Spears and Miller-Young, 2006;Spears et al, 2007Spears et al, , 2005. Hence, a FE model of the heel during bedrest, as related to HU, is missing in the literature.…”

Role of gastrocnemius–soleus muscle in forefoot force transmission at heel rise — A 3D finite element analysis

“…The plantar soft tissue was modeled by the incompressible, hyperelastic Ogden formulation (1st-order), a constitutive model that has previously been reported in literature to model nonlinear plantar soft tissue material behavior Spears et al, 2007). The strain energy function U of the Ogden model employed was defined by:…”