برگشت پذیری

Recently, the use of coronary stents in interventional procedures has rapidly increased. Biodegradable magnesium alloy stents gained increasing interest in the past years due to their potential prospect. However, for the magnesium alloy stents to be feasible for widespread clinical use, it is important that their performance can be compared to modern permanent stents. In this project, a finite element method is used for investigating the effect of the stent geometry and material properties on its behavior. The stent designs made with two different materials, stainless steel 304 and magnesium alloy AZ 31, and the Palmaz-Schatz geometry are modeled and their behavior during the deployment is compared in terms of stress distribution in the stent, vessel wall, plaque as well as in terms of outer diameter changes, radial recoil ratio, axial recoil ratio and Foreshortening. Moreover, the effect of stent material properties on the restenosis after coronary stent placement is investigated by comparing the stress distribution in the arteries. According to the findings, the possibility of restenosis after coronary stenting is lower for magnesium alloy stents in comparison with stainless steel 304 stent.

Gait rehabilitation using body weight support on a treadmill is a recommended rehabilitation technique for neurological injuries, such as spinal cord injuries. Over the last few years, the use of robots in gait rehabilitation has been considered. The robots can substitute physiotherapy training, and are particularly suitable when the exercise is very intensive. Moreover, robots can reduce therapist intensity and the exercise time can be increased. This paper introduces a new robotic orthosis for the automation of treadmill training. The robot design basis is body weight supported treadmill training (BWSTT). In doing So, a part of the body weight is balanced using a supporting system. Then, the patient is placed on the treadmill and the walking algorithm is applied to the leg using an exoskeleton to perform the rehabilitation exercises. In the design, many criteria such as the low inertia of robot components, backdrivability, high safety, and degrees of freedom, based on human walking, are considered. This robot is composed of a leg exoskeleton for leg control and a segment for pelvis control. In the exoskeleton, two degrees of freedom are considered for the hip joint and one degree of freedom for the knee joint and two degrees of freedom are considered for the pelvis. Different tests are designed to investigate the performance of the robot. Measuring the inertia of this robot reveals that it exhibits less resistive forces compared to other existing rehabilitation robots. Furthermore, different walking algorithms of a healthy human are applied to the robot with an artificial leg on a treadmill. Primitive tests, with artificial legs and healthy humans, indicate that the robot has enough capability of fulfilling the walking algorithms. It can be concluded that the presented robot has the necessary design criteria, such as suitable degrees of freedom, low inertia and high safety, and so, is suitable for use in gait rehabilitation exercises.