Assessing Functional Changes With the Integration of Wrist Flexion Into a Myoelectric Prosthesis

This study investigates functional performance using a two-degree-of-freedom (2DOF) prosthetic wrist compared to a single-degree-of-freedom (1DOF) wrist in individuals with transradial (below-elbow) amputation. Five participants were fitted with a custom-designed 2DOF prosthetic wrist system integrated with an Ottobock Transcarpal hand and operated via a pattern recognition-based myoelectric control interface. Participants completed two test conditions: one using wrist rotation alone (1DOF, NoWF), and another using wrist rotation combined with wrist flexion and extension (2DOF, WF). A battery of standardized functional assessments was used to evaluate performance in both conditions, including the Southampton Hand Assessment Procedure (SHAP), Box and Blocks Test (BBT), Jebsen-Taylor Hand Function Test (JTHFT), Activity Measure for Upper Limb Amputees (AM-ULA), Clothespin Relocation Task (CRT), and the Assessment of Capacity for Myoelectric Control (ACMC). Across all outcome measures, no statistically significant differences were found between the 1DOF and 2DOF conditions. While the lack of measurable improvement may reflect the influence of factors inherent to the 2DOF design, such as its greater length, added mass compared to 1DOF wrists, or increased control complexity, the results nonetheless indicate that the addition of a second wrist degree of freedom did not compromise functional performance. These findings suggest that more complex multi-DOF systems can be implemented without detriment to user function, an encouraging result for the continued development of advanced upper-limb prosthetic technologies.