Title: Assessing lower limb proprioception with a novel mechatronics device
Supervisors: Dr. Jean-Sébastien Blouin
Committee members: Dr. Calvin Kuo, Dr. Martin Héroux
Abstract:
The ability to sense the position, orientation, and movement of our body without looking at it is crucial for everyday activities like standing upright, navigating the world or reaching for something. This internal sense, called proprioception, combines information from various sensors located in our joints, muscles, skin, and tendons to create an internal representation of the body position and orientation. Multiple tests of proprioception have been proposed but these typically involve testing a specific joint and have limited functional implications. Here, I developed a novel mechatronics system to assess lower limb proprioception in a functional context: standing balance. As stance width is a key factor for the control of balance, I propose a novel proprioceptive assessment method to quantify detection thresholds to changes in stance width.
I will recruit 32 healthy adult participants which will be divided into two experimental groups. For the first experimental group, I will measure the proprioceptive thresholds to a imposed stance width changes while freely balancing. I will examine how the thresholds, measured in terms of support surface movement velocity, vary as a function of the support surface displacement amplitude. I hypothesize that movement velocity thresholds will decrease as displacement amplitude increases. For the second group of participants, I will examine the effect of changing initial stance width on the estimated proprioceptive thresholds. I hypothesize that proprioceptive threshold to an imposed stance width change will be higher when balancing with a larger initial stance width due to increased noise at the hip joints that result from whole-body movements. Also, I will test the impact of body immobilization on the measured thresholds. Given that whole-body immobilization removes postural sway, I hypothesize that proprioceptive thresholds will decrease due to the reduced noise at joints. The proposed study will contribute to our understanding of the limits of the lower limb proprioceptive system. Potentially, the findings can be used to develop a functional test of proprioception and simplified version of our current mechatronic platforms, which will be beneficial both in assessing clinical conditions with proprioceptive deficits. Lastly, the results can help construct future experiments that explores the body’s response to sub-threshold perturbations which will give insight into the functions of the body’s balance controller.