Grant: Research Tools and Instruments

The foot and ankle are critical structures that are essential to human locomotor tasks across a wide range of environments. With 26 bones, 33 joints, and over a hundred tendons, muscles, and ligaments, the foot and ankle are inherently complex structures and remain one of the least biomechanically understood parts of the human body. During locomotion, bones of the foot and ankle experience tremendous loads. However, with so much complexity, the foot and ankle have the ability to adapt, deform, and sense the environment it is interacting with to allow humans to move effortlessly across a variety of terrains. How the foot and ankle are able to perform locomotor tasks eloquently is unknown and this understanding is essential because any dysfunction in the foot and ankle severely compromises locomotion. The purpose of this NSERC RTI is to request funds for the building of a robotic device that can record bone motion and loading as well as control both the intrinsic and extrinsic muscles of the foot and ankle - this device will be named the Cadaveric, Robotic Ankle-Foot Treading (CRAFT) simulator. The current state-of-the-art in robotic gait simulators manipulates the extrinsic muscles to produce gross motions of the cadaveric foot-ankle, while recording ground reaction forces. But recent evidence shows that the intrinsic muscles are also critically important for modulating mid-foot and arch behaviors in vivo, yet there is no way to actuate these muscles with existing gait simulators. Further to this point, there is currently no research that has thoroughly characterized how the intrinsic muscles, tendons, and ligamentous network distribute forces throughout the foot during many day-to-day activities such as standing, walking, or running. We therefore propose the CRAFT Simulator as a new gait simulation device that will control the force/stiffness of up to a dozen extrinsic and intrinsic muscles of the foot and ankle. This device will be coupled with measurements of three-dimensional bone motions with advanced imaging technologies using two different designs. In Design 1, a Stewart Platform will apply forces to the human foot with a mounted force plate and optical motion capture device will record bone motion with controlled ground reaction forces. In Design 2, the device will be modified to be compatible with imaging technologies such as dynamic computed tomography (CT), weight-bearing CT, and dual-fluoroscopy to capture more comprehensive bone motion and loading of the foot and ankle with the robotic control of intrinsic and extrinsic muscles of the foot. This robotic device will be used to facilitate experiments and model identification of the foot's role in load bearing, whole body stability, and locomotion. The robotic device will provide a rich training environment for HQP allowing new research applications and industrial product development of footwear, prosthetic feet, orthotic devices, and wearable sensors in both academia and industry.