October 13, 2011

Spanish Team Designs Customizable Active Knee-Ankle Orthosis

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A team from the Department of Mechanical Engineering and the Center for Research and Biomedical Engineering of the Universitat Politècnica de Catalunya (UPC), Spain, also known as UPC-Barcelona Tech, has developed a customizable active knee-ankle orthosis (KAO)to assist gait in people who have limited control over the movement of their knee and ankle joints due to incomplete spinal cord injuries (SCI). Collaborating universities include the Universidade da Coruña, Spain, and the Universidad de Extremadura, Spain, and the team members include engineering, medical, and orthopedic professionals.

Photograph courtesy of UPC-Barcelona Tech.

The first device developed within the framework of the project is an active knee-ankle orthosis. The prototype orthosis was designed and built at the Escola Tècnica Superior d’Enginyeria Industrial de Barcelona (ETSEIB), where researchers analyzed the dynamics of the human gait with an optical system consisting of 12 cameras that measure and capture the movement of the human body while a subject is walking. The system can simultaneously measure foot-ground contact force by means of force plates that contain four triaxial force sensors. The results are used to design devices that support movement in people with incomplete SCIs. Josep Maria Font, PhD, is the UPC researcher responsible for designing the first prototype.

The system incorporates robotic and orthopedic technology. A novel feature of this active knee-ankle orthosis is the mechanical design of the knee joint, which incorporates two independent systems for activating and locking the joint. This allows the device to provide better support at different phases of the gait cycle and reduces energy consumption.

Now that the active orthosis prototype has been built, a group at the Universidad de Extremadura Department of Mechanical, Energy, and Materials Engineering will continue the project. Their role is to design and install the electronic system that controls the movement of the device. The motor, located on the side of the knee, is activated and deactivated based on information received from two sets of sensors: plantar sensors, which detect foot-ground contact, and sensors that measure the joint angles to determine what phase of the gait cycle the user is in.

The goal of the Mechanical Engineering Laboratory of the Universidade da Coruña is to develop a dynamic simulation program that will make it possible, based on gait analysis and modeling of the human body, to predict how a person with an SCI will move when wearing the orthosis. With this information it will be possible to design customized assistive devices for each patient. Researchers said that the simulation ensures that the orthosis will be as good a match as possible for the end user, and it saves money and time because it will no longer be necessary to go through a trial-and-error process using real components.

The device will be tested on patients at Juan Canalejo Hospital, A Coruña, Spain, a facility linked to the Universidade da Coruña. Testing will serve to validate the simulator and wider use of the orthosis.

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