CURRENT AND FUTURE ASPECTS OF WEIGHTBEARING CT-BASED SHAPE MODELLING

Traditionally, anatomical variability of the human musculoskeletal system is assessed using measurements based on 2D images (e.g. radiographs) and primarily focuses on bone-to-bone alignment. 3D image based statistical shape models, however, allow to quantify such variations in a 3D manner as well as considering geometrical variations. Using data reduction techniques, bone geometries from a specific population can be used to determine an average shape but also the primary variations of individual bones, joints, or body segments. With respect to the foot-ankle complex, statistical shape modelling has been applied to individual bones (e.g. talus or calcaneus) as well as specific foot-ankle joints (e.g. subtalar, talonavicular, calcaneocuboid). Despite their potential to enhance our understanding of the structure/function relationship, statistical shape models of the whole foot-ankle complex are currently sparse - and are typically limited to unloaded conditions. Recent technological developments using weightbearing computed tomography (CT) allow to image and thus quantify the foot-ankle structure in a loaded condition. This enables the assessment of load-related parameters such as 3D alignment of the ankle and subtalar joint, which might be missed in the traditional supine imaging position. Within this study, we aim to compare foot-ankle statistical shape models generated from conventional supine 3D CT images (Killen et al., WCB 2022) with models based on novel weightbearing CT images in both healthy control subjects and patients with a flat foot pathology. By comparing primary geometrical variations, sensitive to the loading condition, we hope to gain a more detailed understanding of the role of anatomical variations of the foot-ankle complex on dynamic foot-ankle function in both a healthy and flat feet population.