Is it Finger or Wrist Dexterity That is Missing in Current Hand Prostheses?

Area of Science:

• Biomedical Engineering
• Rehabilitation Engineering
• Prosthetics Design

Background:

• Current prosthetic hands often lack sufficient degrees of freedom (DoF), leading to compensatory movements.
• These compensatory movements can cause residual limb pain and overuse syndromes in amputees.
• Limited research has focused on the crucial role of the wrist in prosthetic hand function.

Purpose of the Study:

• To investigate if a prosthetic hand with wrist flexion/extension (1 DoF) can match the performance of a multi-DoF hand without wrist articulation.
• To evaluate the impact of shifting dexterity from the hand to the wrist on task performance and compensatory movements.

Main Methods:

• Emulation of four hand-wrist prosthesis architectures.
• Utilizing the Southampton Hand Assessment Procedure (SHAP) for performance evaluation.
• Assessing compensatory movements in unimpaired subjects using orthoses.

Main Results:

• Shifting prosthetic dexterity to the wrist (flexion/extension) maintained task performance for transradial amputees.
• This approach showed limited impact on compensatory movements compared to multi-DoF hands.
• Performance with a 1 DoF wrist-focused prosthesis was comparable to a multi-DoF hand-only prosthesis.

Conclusions:

• Prioritizing wrist function in prosthetic design is a viable strategy for improving functional outcomes.
• This approach may help mitigate pain and overuse syndromes associated with compensatory movements.
• Rehabilitation engineers should explore novel artificial wrist architectures for advanced prostheses.