Quantitative assessment of four men using above-elbow prosthetic control

Area of Science:

• Biomedical Engineering
• Rehabilitation Science
• Prosthetics and Orthotics

Background:

• Above-elbow (AE) amputations present challenges for prosthetic control.
• Myoelectric prostheses offer advanced control but require effective user interfaces.
• Evaluating prosthetic performance necessitates understanding both constrained and unconstrained tasks.

Purpose of the Study:

• To investigate the relationship between kinematically unconstrained activities of daily living (ADL) and a kinematically constrained task in AE amputees.
• To compare the performance of a conventional velocity elbow control scheme with a novel "natural" controller.
• To assess the synergistic shoulder-elbow joint coordination during a constrained task.

Main Methods:

• Four male subjects with unilateral AE amputation participated.
• Subjects used a myoelectric prosthesis with two distinct elbow control schemes (conventional and "natural").
• Performance was evaluated through timed ADL tasks (meat cutting, sock donning, dough rolling) and a constrained crank-turning task, quantifying shoulder-elbow coordination.

Main Results:

• Significant differences in performance were observed between the two controllers for the crank-turning task.
• No significant performance differences were found for the ADL tasks between the controllers.
• A strong positive canonical correlation (0.77) was identified between time-based and crank domain measures.

Conclusions:

• Biomechanical assessments are crucial for a comprehensive evaluation of AE amputee performance with myoelectric devices.
• Integrating time-based clinical tests with biomechanical assessments provides a more complete understanding of prosthetic function.
• Current myoelectric control schemes may not universally improve performance across all functional tasks.