A Task-Agnostic Hip Exoskeleton for Osteoarthritis Pain Relief: Energetic Control Across Activities of Daily Life.

Hip osteoarthritis (OA) affects millions worldwide, yet effective conservative (non-surgical) treatments are still limited. Conventional hip braces cannot reduce painful joint loads associated with contractile forces from flexors and extensors during locomotion. Powered hip exoskeletons could potentially reduce biological hip moments by applying flexion/extension torques, thus attenuating muscle forces that contribute to OA pain. Here, we present a novel task-agnostic controller for a backdrivable hip exoskeleton that relieves hip O A pain across the primary activities of daily life. Inspired by the energy shaping method, this controller utilizes biomechanicsbased components to assist with level walking, ramp and stairs ascent/descent, and sit-to-stand transitions, which can be customized to different populations, like hip OA. In a pilot study with three hip OA participants, the hip exoskeleton holistically reduced pain and perceived difficulty during a multi-activity test (except difficulty of level walking). The exoskeleton also increased hip range of motion during walking, with subject-specific improvements in walking speed. This pilot study suggests that hip exoskeletons may offer a promising new intervention for managing hip O A.