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Circumferential force production of the thumb
Zong-Ming Li1, Daniel A Harkness
1Hand Research Laboratory, Musculoskeletal Research Center, Departments of Orthopaedic Surgery of Bioengineering, E1641 Biomedical Science Tower, University of Pittsburgh, 210 Lothrop Street, Pittsburgh, PA 15213, USA. zmli@pitt.edu
Medical Engineering & Physics
|October 9, 2004
Summary
Researchers developed a new apparatus to measure finger grip strength in all directions. Maximal force was found in the flexion/adduction direction, highlighting potential for detecting neuromuscular disorders.
Area of Science:
- Biomechanics
- Human Physiology
- Hand Function Assessment
Background:
- Assessing maximal grip strength is crucial for evaluating hand function.
- Previous methods often focus on specific directions, limiting comprehensive analysis.
- Understanding circumferential forces is key to diagnosing neuromuscular disorders.
Purpose of the Study:
- To develop and validate an apparatus for measuring maximal continuous circumferential forces of the digit.
- To characterize the force envelope and identify maximal force directions in asymptomatic hands.
- To explore the potential of this method for detecting neuromuscular impairments.
Main Methods:
- An apparatus was designed to measure forces in the transverse plane, perpendicular to the digit's longitudinal axis.
- Subjects with asymptomatic hands produced maximal forces in all directions at the proximal phalanx of the thumb.
- Force components were recorded to construct a subject-specific force envelope.
Main Results:
- The force envelope stabilized after several trials, demonstrating reliability.
- The force envelope was asymmetric and oblique, with maximal force (112.1 ± 14.8 N) in the flexion/adduction direction.
- The lowest force was 50.3% of maximal in the extension/abduction direction, with other directions showing varied force outputs.
Conclusions:
- The developed apparatus provides a comprehensive measure of circumferential hand forces.
- The asymmetric force envelope suggests directional biases in thumb strength.
- This method shows promise for identifying deviations indicative of neuromuscular disorders.