An Adaptable Prosthetic Wrist Reduces Subjective Workload

Many presently available prostheses lack a functional wrist. To fill this niche and to better understand the impact a wrist has in prosthetic functionality, we designed a low-cost, adaptable, 3D-printable prosthetic wrist that can be adapted to various prosthetic hands and sockets. The wrist utilizes inexpensive but powerful servo motors to provide simultaneous and proportional control of two degrees of freedom: pronation/supination and flexion/extension or radial/ulnar deviation. Participants used both our wrist and a commercially available wrist (DEKA \"LUKE\" Arm) to complete a modified version of the clothespin relocation task with and without the wrists enabled. Through use of the NASA Task Load Index we found that both wrists significantly reduced the subjective workload associated with clothespin relocation task (p < 0.05). However, we found no significant difference in task completion speed, presumably due to compensation strategies. This inexpensive and adaptable prosthetic wrist can be used by amputees to reduce task workload, or by researchers to further explore the importance of wrist function.