A Comparison of Two Combined Shape Modeling Approaches of Knee Bones for Patellofemoral Instability

Motivation: Statistical shape models (SSMs) used to quantify musculoskeletal pathologies generally ignore correlations in shape and orientation across bones. Goal(s): The goal of this study was to investigate alternative approaches for modeling bone shapes in subjects with and without patellofemoral instability (PFI). Approach: Two models, one using combined point sets and the other using combined SSMs of the knee (femur, patella, and tibia), were created from MRI-based reconstructions and compared in terms of compactness, specificity, generalizability, and separability. Results: The combined points model was more specific and general while the combined SSMs model showed better separability between control and PFI subjects. Impact: Better characterization of the shapes and orientations of skeletal morphologies and their correlations could lead to improved diagnosis and more targeted treatments for musculoskeletal pathologies such as PFI.