Subject Specific Knee Joint Modelling Based on In Vivo Clinical Data

The knee is one of the most complex and studied joint of the musculoskeletal system provided its great importance in locomotion. Therefore, a deep understanding of its behaviour and of the role played by each of the structures composing it is fundamental. Knee joint models are an invaluable tool to understand the behaviour of the knee and their usefulness is proved in many fields such as surgical planning and prosthetic design. A huge amount of models has been proposed in the literature focusing on the kinematic, the kinetostatic and the dynamic behavior of the joint. Models can be based on in vivo or in vitro data. While the kinematic and the kinetostatic models are defined properly on in vitro data, the dynamic ones cannot. This discrepancy leads to a gap, a lack of coherence, between the usually in vitro defined kinematic and kinetostatic models and the study of the active structures of the joint. In order to achieve a comprehensive knee joint description in which the kinematic, kinetostatic and dynamic models coherently stem one from the other, the identification of a procedure that allows to obtaining reliable kinematic and kinetostatic models in vivo is needed. In the present dissertation a procedure is defined that allows for the identification of a subject specific knee joint model in vivo starting from standard clinical data obtained by the use of non invasive techniques such as computed tomography (CT), magnetic resonance imaging (MRI) and fluoroscopy. This procedure leads to an accurate identification of the parameters needed to personalize the 5-5 parallel mechanism and its patello-femoral extension on a single patient in order to accurately reply the knee joint original motion. Furthermore, following the sequential approach to the modelling of the joint, a stiffness model of the knee is specialized on the specific subject's anatomy.