Developpement d'une approche d'evaluation clinique de la cinematique tridimensionnelle du genou durant la marche pour des patients gonarthrosiques

The general purpose of this study was to propose a biomechanical approach, applicable in a clinical context, for evaluating three-dimensional (3D) angular kinematic parameters at the pathological knee level of osteoarthritis (OA) patients during gait. Specific objectives were to determine the feasibility of the measurement method here proposed (study 1) and to evaluate psychometric properties like construct validity (in study 2 and a section of supplementary analyses) and reliability (in study 3) of the knee angular kinematic parameters.;The second study (on construct validity) aimed at finding 3D knee angular kinematic parameters apt to discriminate OA patients from the AS participants or to find parameters that were sensitive to the evolution of the structural deterioration of the knee joint (with regard to the radiographic severity). OA patients were subdivided in four subgroups (OAKL1, OAKL2 , OAKL3 and OAKL4) for analysis purposes. In order to determine significantly discriminating parameters, analyses of variance using contrast AS vs. OAKL1,2,3,4 (regrouping the four OA patients' subgroups) were performed on the 22 knee angular kinematic parameters. To identify from these parameters those that covaried significantly with the deterioration of knee joint, analyses of isotonous variation (E 2) were realised. Nine parameters resulting of the analysis of the three plans of joint motion (flexion/extension, adduction/abduction and internal/external tibiae rotations) were significantly sensitive to the progressive deterioration levels of the knee. Four parameters, all resulting from the analysis of the frontal plane of joint motion (adduction/abduction), were significantly discriminating. Furthermore, additional analyses (correlation coefficients and Dunnett's t-tests) showed that three parameters (amplitude of motion in the frontal plane as well as varus bending, both occurring during the loading phase of gait, and frontal knee misalignment during the phase of single support of gait) are knee angular kinematic measurements having a better discriminating capacity than other biomechanical measures that have been recognised as development and progressive factors of knee OA (static knee misalignment in varus/valgus and external knee adduction moment parameters). Comparisons between the clinical measurements (from the battery of clinical tests) with the biomechanical measurements have shown that the parameter measuring varus bending around the knee during gait was significantly associated to knee pain and to the physical function of knee OA patients.;The last study was conducted to determine the test-retest reliability (measurement property related to inter-session stability) of the 3D knee angular kinematics parameters that have been shown to be discriminating or sensitive to the deterioration levels of knee joint at the second study. The intra class coefficients of correlation (ICC) obtained all reached over 0.75 and the associated standard errors of measurement (SE) were lower than 3.0°. These results show that the biomechanical method of measurement proposed in this research allows the evaluation of reliable 3D angular kinematic parameters at the pathological knee level of OA patients. (Abstract shortened by UMI.);The first study (on the feasibility of the measurement method) was focused on the determination of the effects of wearing the exoskeleton on pain in the pathological knee (results of VAS) and on gait patterns of the OA patients (assessed by the spatiotemporal as well as by the force and time-force parameters). These effects were evaluated across the biomechanical follow-up in order to estimate their inter-sessions stability. Analyses of variance were realised to determine statistical significant changes. Wearing the exoskeleton induced a small increase of knee pain (10 mm on average) which was statistically significant and, from a practical point of view, on the border of clinical significance. Wearing the exoskeleton altered significantly one of the 13 spatiotemporal parameters analysed and 14 of the 42 force and time-force parameters. Over all, observed effect sizes were less than 7%. The results obtained on gait parameters demonstrated that patients preserved gait symmetry for the two lower limbs, but they adopted a more cautious gait strategy when walking with the exoskeleton. Moreover, all effects observed in this study were stable across the three sessions of gait analysis.