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

Area of Science:

• Biomedical Engineering
• Rehabilitation Science
• Prosthetics and Orthotics

Background:

• Transradial amputees often face functional limitations with current prosthetic devices.
• Advanced prosthetic wrists aim to restore more natural hand and wrist movements.
• Evaluating the functional impact of additional degrees of freedom (DOF) in prosthetic wrists is crucial for technological advancement.

Purpose of the Study:

• To compare the functional performance of a two-degree-of-freedom (2DOF) prosthetic wrist against a single-degree-of-freedom (1DOF) system in individuals with transradial amputation.
• To assess whether adding wrist flexion/extension (2DOF) to wrist rotation (1DOF) enhances or compromises functional outcomes.
• To provide insights into the usability and effectiveness of multi-DOF prosthetic wrist systems.

Main Methods:

• Five participants with transradial amputation were fitted with a custom 2DOF prosthetic wrist system.
• Participants performed standardized functional assessments under two conditions: 1DOF (rotation only) and 2DOF (rotation with flexion/extension).
• Outcome measures included the Southampton Hand Assessment Procedure (SHAP), Box and Blocks Test (BBT), Jebsen-Taylor Hand Function Test (JTHFT), and others.

Main Results:

• No statistically significant differences in functional performance were observed between the 1DOF and 2DOF prosthetic wrist conditions across all tested outcome measures.
• Despite potential design challenges of the 2DOF system (e.g., increased length, mass, control complexity), it did not lead to a decline in functional performance.
• Individual functional assessment scores showed no detriment with the addition of the second degree of freedom.

Conclusions:

• The addition of a second degree of freedom (wrist flexion/extension) to a prosthetic wrist system did not negatively impact functional performance in transradial amputees.
• This suggests that more complex multi-DOF prosthetic systems can be developed and implemented without compromising user function.
• Findings support the continued development of advanced upper-limb prosthetics with enhanced kinematic capabilities.