A novel analytical pipeline quantifying variance in foot morphology and function using statistical shape modelling and a 26-segment foot model.

The aim of this thesis is to outline an approach applying a statistical shape model and developing a 26-segment patient specific foot model to identify relationships between foot posture and function. The premise of structural and functional variance between different foot arch types exists, however an analytical pipeline using segmentations from medical images integrated into a 26-segment multi-body foot model capable of computing foot function could help address the gaps in knowledge. The proposed method aims to answer questions applied to extremes of foot posture. Knowledge around variance in position and morphology between foot postures is answered using a statistical shape modelling approach to bones of the hindfoot, midfoot and medial ray. Further knowledge relating to motion of the medial ray joints including ankle plantarflexion, subtalar eversion, talonavicular dorsiflexion, talonavicular abduction, talonavicular eversion and first metatarsophalangeal dorsiflexion is generated. The thesis was constructed to enable academics and researchers to apply similar, musculoskeletal modeling pipelines to the foot and ankle in future, and for clinicians to build upon these preliminary findings between foot postures to describe clinical populations using a larger number of patients. Using variations in extremes of foot postures, the thesis shows empirical positional shape differences between high and low arch foot types comparable to the clinical notion of medial longitudinal arch being a significant contributing factor to variance. In addition, subtle morphological differences were also present for each of the bones analysed. Using statistical parametric mapping, the thesis further shows kinematic differences at each of the medial ray joints analysed demonstrating the sensitivity of the 26-segment model to variance in foot postures. The significance of this thesis is in combining two modeling approaches to understand and start to quantitate the relationship between foot structure and function, where flat, normal and high arch foot types showed systematic differences.