Analyse de la dynamique de deux designs de prothèses de genou

Abstract

GOALS: Knee arthroplasty is a common option for patients who suffer from end-stage knee arthritis. There are two types of prosthesis design: one that preserves the cruciate ligaments (2C design) and one that sacrifices them (PS design). The benefits of either approach are still being debated. Some studies have focused on the joint moments at the knee, which give information about the amplitude and the direction of the mechanical action, but the two designs (2C and PS) are yet to be compared directly. The main goal of this project is to compare these two prosthesic designs in terms of moments at the ankle, knee and hip, and to use a new tool (the 3D angle) to determine whether the joints (hip, knee, ankle) are being driven or stabilized. This study is coupled with the analysis of joint power. The first sub-goal is to determine whether the subjects with a TKA adopt a walking strategy that differs from that of healthy subjects. The second sub-goal is to study the stability margin in the medio-lateral and the antero-posterior directions. METHODS: This study has been carried out with a sample of 11 subjects who underwent knee surgery (PS = 5, 2C = 6), including 7 women and 4 men with an average age of 60.18 ± 5.67 (years), a BMI of 33.56 ± 3.37 (kg/m²) and a comfortable walking speed of 1.78 ± 0.63 (km/h). Three walking trials of 45s each have been performed on an instrumental treadmill (AMTI™) with the KneeKG™ harness. The motions of the reflective markers have been recorded by 12 optoelectronic cameras connected to a Vicon™ system. A calibration has been done using the Functional & Postural Method (Hagemeister et al., 2005). The calculation of the joint moments has been performed according to the method described by (Dumas & Chèze, 2007a), and the sign convention according to ISB (Wu, 2002). The calculations of the 3D angle and of the joint power have been made according to the method described by (Dumas & Cheze, 2008). The study on the stability margin has been carried out according to (Robert, 2019). RESULTS: The results show no statistically significant difference between the 2C and the PS, no matter which of the three planes is considered. A greater variability for the 2C subjects has however been observed in all three planes. The same walking strategy is adopted by both TKA and healthy subjects, although we can notice a diminution of the peaks' amplitude in terms of resistance and propulsion. No difference in terms of stability margin in the medio-lateral and antero-posterior directions has been found between PS and 2C subjects. DISCUSSION: The absence of difference in all three planes does not allow us to conclude on the superiority of one or the other prosthesic design. However, the greater inter-subjects variability for the 2C prostheses can be explained by the fact that the PS prostheses are more constrained. Our preliminary study is however limited by the small amount of subjects.

Date	23 Jul 2020
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Nicola Hagemeister (Supervisor) & Raphaël Dumas (Co-supervisor)