Tibiotalar arthrodesis and total ankle replacement (TAR) are the current standards for treatment of end-stage ankle osteoarthritis (OA). Our clinical understanding of the biomechanical causes and risk factors for subtalar secondary OA development following surgical treatment is limited. Dynamic joint level measurements can be investigated in combination with morphology analyses to investigate the form and function relationship of the subtalar joint. The objective of this thesis was to develop a methodology to investigate joint level morphological differences that may influence subtalar joint measurements following tibiotalar arthrodesis and total ankle replacement compared to asymptomatic healthy controls.

Our prior work included calculated in vivo bone kinematics using biplane fluoroscopy in individuals with unilateral TAR or tibiotalar arthrodesis, and healthy controls during an overground walking task. A calcaneus statistical shape model (SSM) was created of the study population. Correspondence particles from the SSM were used to compare joint level measurements across the different groups. During each timepoint of gait, joint space distance and congruence index between matched surfaces of the calcaneus and talus were calculated and paired to correspondence particles;​ these were statistically compared using a temporal statistical parametric mapping analysis. Additionally, from SSM, morphological differences were quantified and characterized using a linear discriminate model to characterize the cohorts.

Minimal statistical significance for congruence index was found when comparing patient groups to healthy controls. However, tibiotalar arthrodesis participants showed an increased joint space distance in the anteromedial facet during early stance that was statistically significant when compared to healthy controls. From the linear discriminant model, the TAR group was closer in shape scores to arthrodesis than healthy controls. Patient groups showed decreased height of the anteromedial facet, including flattening and widening of the posterior facet.

In vivo kinematics combined with SSM provide valuable information concerning the interplay between bone morphology and joint level measurements in patients treated for end-stage ankle OA. We created a methodology to compare measurements of joint morphology. This thesis highlights the complexity of the subtalar joint, the value of robust 3D analyses, and the necessity to further investigate interactions of subtalar function and morphology to clinically evaluate subtalar OA.