Gait analysis before and after a novel personalized system for high tibial osteotomy: statistical analysis of the entire data set and definition of parameters for biomechanical evaluation

Knee arthrosis is one of the most common orthopaedic diseases today and afflicts a large segment of the elderly population. Being a chronic degenerative pathology, its course, although slow, is often inexorable and has as its only solution prosthesisation, an invasive and impactful procedure, particularly for young people, as well as a high health cost. In recent years, there has been an increasing move towards a conservative approach, aimed at preventing the onset of this pathology, by intervening on what has been shown to be one of the main risk factors, such as knee varus. It has been shown how an alteration in knee mechanics, such as varus, is linked to the triggering of arthritic problems in the medial compartment of the tibial plateau. The technique of choice for the correction of this disorder is the high tibial osteotomy (HTO), which allows intervention in the early stages of the pathology. This technique realigns the proximal tibia preserving the patient's tibial plateau and restores physiological loads, delaying or eliminating the need for more invasive surgery. The verification of the effectiveness of this technique represents an open problem in biomechanical assessment; its use at a preliminary stage of pathology in which the subject has not yet undergone major morphological or functional changes means that normal procedures are not suitable for such valuations. Currently, clinical and functional investigations are based on two techniques: gait analysis, and medical imaging. These two tools are used in a complementary manner and provide functional and morphological information on the patient, respectively. Gait analysis provides kinetic and kinematic data (the ground reaction force, or GRF), while medical imaging provides static information about a patient's anatomy. Recently, a link between functional and morphological data has been proposed in the biomechanical assessment of knee pathology, combining morphological data with functional information to characterise external forces with respect to knee anatomy. The aim of this thesis work is to confirm the validity of this innovative procedure, which combines CT images and gait analysis data, to obtain a patient-specific representation of the state of the knee during movement useful in diagnosis and planning of surgery. The present work was performed within a clinical study in which 25 patients with knee varus were enrolled who underwent HTO by means of a procedure that exploits 3D technology from the planning phase to the post-operative evaluation and experiences for the first time the use of a custom-made plate and cutting guides (TOKA®). From the analysis of the functional data, rotations and joint moments, it was possible to demonstrate how the surgical technique had a considerable impact on the joint status, which in the post-operative period showed a substantial approximation to the data of a non-pathological sample, where available, and in general an alteration of the same. In particular, a more physiological trend in knee abd/adduction data was observed after HTO. While the imposition of the GRF in the plane of the tibial plateau, carried out both on the pathological knee and after the HTO, it was seen that the trajectories and force peaks underwent a lateralisation. In the initial phase, it can be seen that the GRF during the stance phase is localised more in the medial area, as are the force and moment peaks, as would be expected for a varus knee, whereas a lateralisation is seen after the procedure.