Evidence for early stance phase pre-loading of the plantar aponeurosis
Journal of Foot and Ankle Research volume 1, Article number: O42 (2008)
An inverse dynamics approach has been used to gain an insight into the mechanical behaviour of the plantar aponeurosis (PA) at different walking speeds. Mechanical  and finite element models  have evaluated its biomechanics in quasi static conditions. To our knowledge only one study has addressed the dynamic behaviour of the PA with relation to the Achilles tendon force . The aims of this study were to create a multibody model to quantify PA tension and to examine how PA tension changes with walking speed.
Three healthy young subjects with no history of foot injuries or abnormalities participated in this study. A linear ultrasound probe was employed to identify the proximal attachment of the PA onto the plantar heel. An ad hoc 12 markers protocol, modification of , was designed to record the kinematics of heel, metatarsal bones and toes at different walking speeds.
Commercial software for multibody dynamics analysis (MSC.Adams) was used to build the model geometry and to calculate the elongation trajectories for five segments of the PA based on stance phase kinematics data (Figure 1). The metatarsal heads were modelled as cylinders under the metatarso-phalangeal joints. The windlass mechanism of the PA was modelled by contact elements that constrained the PA segments to wrap around the metatarsal heads. Bulk PA stiffness  was distributed equally among the five digits and was used to estimate segmental PA tension.
Preliminary results demonstrate model validity and reveal an interesting relation between PA tension and walking speed. The increase in PA tension with walking speed during early stance may represent a pre-loading protective mechanism to further support the longitudinal arch at higher impact forces.
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Caravaggi, P., Pataky, T.C., Savage, R. et al. Evidence for early stance phase pre-loading of the plantar aponeurosis. J Foot Ankle Res 1 (Suppl 1), O42 (2008). https://doi.org/10.1186/1757-1146-1-S1-O42
- Achilles Tendon
- Walking Speed
- Stance Phase
- Metatarsal Head
- Multibody Model