3D-printed custom-designed prostheses for partial hand amputation: mechanical challenges still exist

Study Design: This is a technical report involving evaluation of two 3D-printed custom-designed prosthetic prototypes for an adult male with partial amputation of his dominant hand. Introduction: Prosthetic solutions for partial hand amputations have progressed modestly in comparison with advances in full hands for transradial and higher amputations. 3D-printing technology allows Bespoke prosthetic design and rapid prototyping, but evidence regarding functional performance and consumer ratings of devices is lacking. Purpose of the Study: The purpose of this study was to compare grip strength, dexterity, and consumer perceptions for two novel 3D-printed devices with a myoelectric prosthesis. Methods: This study involves a 2-year iterative design process with an input from the participant, engineers, a prosthetist, and a hand therapist. The evaluation involved standardized tests of grip/pinch strength and dexterity and participant ratings of key criteria. Results: Both 3D-printed devices had very poor grip and pinch strength but comparable dexterity with the myoelectric prosthesis. The participant was more satisfied with the weight and thermal attributes of the 3D-printed devices. Discussion: Aspects of both 3D-printed designs showed the potential for future refinements; however, the mechanical solutions to minimize force required at the wrist to activate grip are still required. Conclusion(s): Future design efforts should be client-centered and involve professionals with specialist prosthetic and engineering knowledge.