Development of a hand dynamometer for the control of manually applied forces

Area of Science:

• Biomechanics
• Rehabilitation Engineering
• Manual Therapy

Background:

• Manual therapy involves applying forces to treat musculoskeletal conditions.
• Inconsistent force application can lead to suboptimal treatment outcomes.
• Existing methods lack objective feedback on applied forces.

Purpose of the Study:

• Develop a prototype tool for instantaneous feedback on manually applied forces.
• Assess force constancy during varied application postures.
• Compare tactile stiffness sensitivity with and without the tool.

Main Methods:

• Utilized a modified JAMAR dynamometer as a mobilizing tool.
• Subjects applied Grade II and IV mobilizing forces at near, midway, and far body positions.
• Stiffness discrimination was tested using hands alone versus the tool.

Main Results:

• Grade II force was maintained at varying distances, but Grade IV force decreased.
• Significant within- and between-subject variation in applied force was observed.
• Stiffness discrimination sensitivity was comparable between hands-only and tool-assisted methods.

Conclusions:

• Instantaneous force feedback can potentially improve control over manual therapy forces.
• Developing tools to control applied force and distribute load may mitigate hand injuries in therapists.
• Further research is needed to refine devices for enhanced manual therapy practice.