Designing a wearable sensor system to monitor the internal mechanism of a stance-phase control passive prosthetic knee

Reding, Rachel 1, 2 ; Andrysek, Jan 1, 2

1. Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2. Bloorview Research Institute, Holland Bloorview Children's Hospital

Gait is the repetitive locomotion of the leg, and gait analysis is often used to study pathological gait. One example of pathological gait can be observed in amputees. There are several causes of amputation, including congenital defects, trauma, diabetes, cancer and vascular disease. One in 150 North Americans are currently living with an amputation, 65% of which involve the lower limb and of which 30% are above-the-knee. Prostheses and prosthetic rehabilitation are the most common form of treatment for these amputees and generally help amputees regain function, but amputees still face problems such as fear of falling and injuries associated with falling. Gait analysis in amputees is important to improve prosthetic knee design and adjustments to address some of these problems. The focus of this study is creating a wearable gait analysis tool for above-knee amputees who use a stance-phase passive prosthetic knee.

This project aims to further develop a testing system to determine the performance of the All-Terrain Knee, a monocentric knee prosthesis that utilizes the articulation of a knee lock to facilitate gait for above-the-knee amputees. The purpose of this project is to better understand the internal locking mechanism as it relates to kinematic gait events, as well as create a self- contained and portable testing unit. The wearable gait analysis tool will be prototyped and used in validation trials with amputee and able-bodied users wearing a gait simulator to determine the performance of the tool when compared to a standard gait analysis method (using a load transducer).

Since this is a wearable tool, the data will provide more insights about above-knee amputee gait in real-life settings where amputees face instability, which will better inform the design changes and prosthetic adjustments. Moreover, the empirical data has the possibility of being inputted into computer models of the prosthetic knees to better characterize the performance of the knee designs and allow for predictive capabilities of the knee in different environments. Overall, it is a new technique that can be applied to other passive knees because there is flexibility in the sensors chosen for the wearable gait analysis tool.