Users of mechanical prosthetics have been left behind since WWII. Vast amounts of money and research have been devoted to electrical devices resulting in disappointing outcomes and little advancement for the last 40 years. Most notably, Colonel Geoffrey Ling of DARPA’s Defense Science Department told Weill Cornell Medicine “Upper extremity limb replacement has not really progressed since the days of Captain Hook.” The broader sentiment of active prosthetic users is best summed by Wolfe Schweitzer, an amputee himself and University of Zurich Forensic Science Scholar, “Myoelectric prosthetic arms do not "really" work, we all know that, and it has been clear for decades. Due to the high degree of error rates inherent to myoelectric control, use of a myoelectric arm for actual grips in everyday life as well as work related activities constitutes a risky behavior.” Creating true advancement and innovation is the broader societal need, while meeting this need presents an opportunity of increased productivity for every active transradial amputee.
Right now body-powered mechanical upper limb prosthetics are divided into two categories: voluntary opening (VO) and voluntary closing (VC). Within the VC category exists one sub-category: voluntary closing and locking (VC&L). Though the VC&L of its time was an incredible advancement in 1948 it has been left behind because it is unserviceable. The active users of voluntary closing and automatically locking hooks need help because they suffer a deficit of modern engineering. Their prosthetists need help because they have limited choices to present to the patient. This highly functional terminal device often catastrophically fails thus leaving the amputee without any device for weeks at a time. This common occurrence is at a great cost to the amputee financially, emotionally, and productively. They are struggling because the intuitive prehensor action of a voluntary closing and locking hook is superior to the voluntary opening hook, but the only VC&L device currently available lacks durability and serviceability. Our innovation meets both of those needs. The novel engineering separates the internal wear components from the exterior housing and fingers. It is a terminal device in the VC&L sub-category: automatically locking in any position with replaceable internal parts.
