L'objectif de ce travail était de comparer les enregistrements électrogoniométriques de la marche d'un groupe témoin de 9 sujets et de 2 groupes de sujets porteurs de prothèses totales de genou, conservant ou sacrifiant le ligament croisé postérieur (LCP), comportant respectivement 10 et 6 patients. La marche a été étudiée en terrain plat à 3 vitesses différentes. Nous avons recueilli les angles de flexion-extension du genou et les principaux paramètres spatio-temporaux de la marche.

La marche s'effectuait de la même façon avec les prothèses conservant ou sacrifiant le LCP, malgré les différences théoriques de cinématique articulaire entre les deux implants. Il existait une modification de la phase d'appui, pendant laquelle l'amplitude de flexion était liée à la vitesse et était diminuée dans le groupe des prothèses. Cette diminution d'amplitude se répercutait probablement sur la qualité de la marche car elle était corrélée avec une diminution des paramètres spatio-temporaux en rapport avec la performance de la marche.

Nous avons attribué cette diminution d'amplitude pendant la marche, que la mobilité sans appui ne laissait pas prévoir, par une interaction entre la cinématique articulaire, le système musculo-ligamentaire et le schéma locomoteur.

We wanted to check whether the differences in joint kinematics between the normal and prosthesis knee, with or without preservation of the posterior cruciate ligament, have an effect on knee flexion-extension during gait and on gait performance.

A control group of nine subjects was compared with two groups of subjects with total knee prostheses, with (n = 10 patients) or without (n = 6 patients) preservation of the posterior cruciate ligament. Gait was studied on flat ground at three different walking speeds. We measured the principal temporospatial gait parameters as well as knee flexion and extension angles using continuous electrogoniometry. Non-parametric statistical tests were used to analyze data due to the small number of subjects in each group.

The flexion-extension cycles were different between the control group and the prostheses groups, but there was no difference between the two prostheses groups. Measurements made during gait confirmed this result, demonstrating a modification of the temporospatial parameters and a decrease in knee flexion during weight bearing in the prostheses groups compared with the control group. The statistical analysis demonstrated a correlation between these two results.

The individual nature of gait parameters hindered data analysis. Indeed, there are many different ways to walk “normally”. We were however able to demonstrate the following points. The theoretical differences in joint kinematics between prostheses with or without preservation of the posterior cruciate ligament did not have any effect on gait. There were however significant differences between the control group and the prostheses groups, and these differences depended on walking speed. The most interesting results concerned the changes in the weight-bearing phase. Flexion during this phase was related to walking speed and was decreased in amplitude in both prostheses groups. This lesser amplitude in knee flexion probably affected the quality of gait because it was correlated with decreased temporospatial parameters related to gait performance.

This decreased amplitude of flexion during gait, which cannot be expected from motion measurements without weight bearing, can be explained by an interaction between joint kinematics, the musculoligamentary system and the locomotor schema.