Julkunen, P. | Search bioRxiv

bioRxiv2023

An Automated and Robust Tool for Musculoskeletal and Finite Element Modeling of the Knee Joint

ObjectiveTo develop and assess an automatic and robust knee musculoskeletal finite element (MSK-FE) modeling pipeline. MethodsMagnetic resonance images (MRI) were used to train nnU-Net networks for auto-segmentation of knee bones (femur, tibia, patella, and fibula), cartilages (femur, tibia, and patella), menisci, and major knee ligaments. Two different MRI sequences were used to broaden applicability. Next, we created MSK-FE models of an unseen dataset using two MSK-FE modeling pipelines: template-based and auto-meshing. MSK models had personalized knee geometries with multi-degree-of-freedom elastic foundation contacts. FE models used fibril-reinforced poroviscoelastic swelling material models for cartilages and menisci. ResultsVolumes of knee bones, cartilages, and menisci did not significantly differ (p>0.05) across MRI sequences. MSK models estimated secondary knee kinematics during passive knee flexion tests consistent with in vivo and simulation-based values from the literature. Between the template-based and auto-meshing FE models, estimated cartilage mechanics often differed significantly (p<0.05), though differences were <15% (considering peaks during walking), i.e., <1.5 MPa for maximum principal stress, <1 percentage point for collagen fibril strain, and <3 percentage points for maximum shear strain. ConclusionThe template-based modeling provided a more rapid and robust tool than the auto-meshing approach, while the estimated knee biomechanics were comparable. Nonetheless, the auto-meshing approach might provide more accurate estimates in subjects with distinct knee irregularities, e.g., cartilage lesions. SignificanceThe MSK-FE modeling tool provides a rapid, easy-to-use, and robust approach to investigating task- and person-specific mechanical responses of the knee cartilage and menisci, holding significant promise, e.g., in personalized rehabilitation planning.

bioengineering↗

bioRxiv2021

Cyclic loading regime considered beneficial does not protect injured and interleukin-1-inflamed cartilage from post-traumatic osteoarthritis

Post-traumatic osteoarthritis is a degenerative musculoskeletal condition where homeostasis of articular cartilage is perturbated by lesions and inflammation, leading to abnormal tissue-level loading. These mechanisms have rarely been included simultaneously in in vitro osteoarthritis models. We modeled the early disease progression in bovine cartilage regulated by the coaction of (1) mechanical injury, (2) pro-inflammatory interleukin-1 challenge, and (3) cyclic loading mimicking walking and considered beneficial (15% strain, 1 Hz). Surprisingly, cyclic loading did not protect cartilage from accelerated glycosaminoglycan loss over 12 days of interleukin-1-culture despite promoting aggrecan biosynthesis. Our time-dependent data suggest that this loading regime could be beneficial in the first days following injury but later turn detrimental in interleukin-1-inflamed cartilage. Consequently, early anti-catabolic drug intervention may inhibit, whereas cyclic loading during chronic inflammation may promote osteoarthritis progression. Our data on the early stages of post-traumatic osteoarthritis could be utilized in the development of countermeasures for disease progression.

pathology↗