Ageing of the human heelpad: tissue properties and gait biomechanics

About the Project

The human heel pad is a complex biological material composed of fat and connective tissue. It is important in impact management during gait, and it is linked to foot pathologies and heel pain. We have recently finished an MRC-funded project (MR/Y010140/1) assessing heel pads in a large sample (n > 200) in three locations: UK, India and Namibia. That study involved field work using portable ultrasound measurements to quantify the thickness of the two layers of the heel pad. Therefore, it remains quite descriptive across the comparative sample. However, for the UK population, we also have foot MRI scans and biplanar X-Ray footage that can provide more insight into the material properties and kinematics of the foot-heel system.

In the proposed project, the student will build on the previous study by doing in-depth characterisation of heel pads, across a range of ages, at the University of Liverpool. Techniques will include lab-based ultrasound scanning, shear-wave elastography, and gait assessment including motion capture, ground reaction force and impact accelerometery measurements. Existing MRI and X-Ray data will be used. Combined, the imaging and experimental data will serve as input in finite element models of “younger” and “older” feet. Within this framework, an inverse finite element simulation approach developed in our previous work (Readioff et al. 2020) will be employed to calibrate subject-specific material parameters of the heel fat pad across the wider population, thereby rigorously quantifying inter-subject and age-related variability in mechanical behaviour. The calibrated finite element models will then be used to evaluate internal stress and strain distributions within the heel pad and adjacent structures (e.g., skin and calcaneus) under physiologically representative loading conditions, with outcomes correlated to in vivo gait characteristics. These models will further provide a platform for simulating the mechanical effects of different footwear configurations (e.g., cushioned versus uncushioned soles, stiff versus compliant heel cups), enabling systematic evaluation of their influence on load transfer and tissue-level response.

This project will uniquely combine highly relevant, descriptive data from three very diverse populations with detailed lab data (incl. shear-wave elastography and biplanar X-Ray) on one of these populations (UK) and advanced modelling and gait analysis. The results will inform us if and how the heel pad ages, and how its mechanical properties influence whole-body gait.

The results will be important for future footwear design and the student will benefit from the Industrial Partner, Vivobarefoot Ltd (London), a leading manufacturer of so-called minimal footwear.