SBIR Phase II: Compliant Nonlinear Quasi-Passive Orthotic Joint

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This Small Business Innovation Research (SBIR) Phase II project aims to create a leg brace that addresses the underlying causes of mild/moderate walking dysfunction affecting 150 million people worldwide. Novel brace elements called Morphologically Switched Orthotic Joints combine field-adjustable, non-linear torsion springs with microprocessor controlled clutches to change the brace's mechanical state dynamically according to the user's gait. Internet updatable software, executing under a multi-processor, fault tolerant brace operating system, samples the brace's 40 sensors to monitor leg posture and activate clutch state transitions. Novel brace concepts include soft/flexible tissue interfaces that adapt to brace misalignment, a joint configuration that provides greater range of motion compared with existing braces, and a fitting scheme with potential for self-fitting capability. Three research objectives are planned: optimize the brace design for comfort level while minimizing interference with Activities of Daily Living (ADL); build/test five prototype braces; and conduct human subjects testing with disabled volunteers to assess brace safety and benefits. Primary biomechanical benefits include dynamically adapting to the user's leg strength to provide full support at all knee angles and reducing the total force across the knee joint by up to an order of magnitude during mobility activities. The broader impact/commercial potential of this project stems from creating a brace that offers biomechanical benefits that substantially surpass those of existing devices without interfering with non-mobile ADL. Anticipated benefits include: allowing Knee Osteoarthritis (KOA) patients to walk with less pain; improving walking/stair-descent safety; adapting to the user's preferred step-length/walking-speed; reducing the effort needed to walk; and allowing a full day of mobile ADL (including a 20-mile walk) on a single battery charge. This will have a transformative effect on the existing leg brace market (120K offloading braces/yr alone) and improve Quality-of-Life for as much as 40% of the world's population suffering mobility dysfunction. The benefit for KOA patients includes a new treatment alternative for multicompartmental or obese KOA patients or for patients who cannot have knee replacement surgery. The benefit for walking/stair-descent safety includes potential for reducing the incidence of falls. Falling accounts for two thirds of accidental deaths and is the leading cause of restricted activity days amongst America's elderly; persons with leg weakness have a four- to fivefold increased risk for falls; directly addressing leg weakness therefore has potential to increase longevity and reduce healthcare spending.