Heel Pad Analysis During Plantarflexion Using a Force Plate and 3D Motion Capture System

Abstract

The calcaneus fat pad or heel pad (HP) is made of a dense, thick layer of corpus adipose, acting as a shock absorber and protecting the calcaneus bone and foot arch from impact injuries. Various factors such as age, gender, and body mass index (BMI) influence the soft tissues of the calcaneus fat pad. Tremendous physical activities, long-standing, rigorous practices, and inappropriate footwear usage cause cracks and discomfort in the heel region, heel pain, and calcaneus fat pad inflammation. This research aims to analyze the HP for different classes of people based on weight category during plantarflexion movement. Based on the BMI, thirty healthy participants without any history of lower limb injuries were selected for the study. Participants were made to perform the plantarflexion movement, which was categorized into baseline, unloading, and loading subphases on the force plate integrated with a 3D motion capture system to capture and analyze the kinetic and kinematic data during plantarflexion movement. The biomechanical outputs, such as stiffness, HP displacement, strain, strain ratios, and compliance, were estimated for all the phases of plantarflexion. Statistical analysis was performed and validated at a 95% confidence level. The findings indicate that the stiffness of HP increases with an increase in BMI, ultimately leading to heel pain. The study’s findings can also be used to design customized shoe soles that relieve heel discomfort for different groups of people.