Lofstrand, or forearm, crutch users experience a concerning amount of force in their wrists that can approach 30% of body weight during swing-through gait, along with hyperextension of the wrist [1]. Such repetitive large loads and poor wrist posture could cause joint pain, injury and carpal tunnel syndrome in long-term crutch users [2].

To address these issues in Lofstrand crutch users, we previously reported two different designs. The first involved attaching a passive orthosis to the grip handle and shaft that directly supported the wrist [3]. The second proposed a soft pneumatic sleeve attached to the forearm cuff of the crutch along with a concept to harvest pneumatic energy during walking via a piston pump at the crutch tip, i.e., the Pneumatic Ergonomic Crutch (PEC) [4].

This paper first describes the full system design of the PEC, which contains an improved pneumatic sleeve orthosis, an energy-harvesting shock-absorbing crutch tip, and a control system with three modes of operation and safety protection. We also present pilot data from one healthy control subject performing a proposed biomechanical evaluation of the pneumatic sleeve orthosis. More tests will be conducted with a group of able-bodied subjects to evaluate the overall effectiveness of the PEC.

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