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Quantifying catch-and-release: the extensor tendon force needed to overcome the catching flexors in trigger fingers
Szu-Ching Lu1, Li-Chieh Kuo, I-Ming Jou
1Department of Biomedical Engineering, National Cheng Kung University, 1 University Road, Tainan, Taiwan.
Summary
Extensor tendons need 1.54 times flexor force to overcome catching in trigger fingers. This biomechanical model quantifies forces, aiding trigger finger understanding and treatment.
Area of Science:
- Biomechanics
- Orthopedics
- Hand Surgery
Background:
- Trigger finger involves unknown extensor tendon forces needed to overcome flexor catching.
- Understanding these forces is crucial for diagnosing and treating trigger finger.
Purpose of the Study:
- To estimate the extensor tendon force required to overcome flexor tendon catching during trigger finger extension.
- To develop a biomechanical model for quantifying these forces.
Main Methods:
- A biomechanical model using moment equilibrium equations and least squares was employed.
- A custom pulling tester measured pulling force, and a motion capture system recorded finger displacement.
- Kinematic and kinetic data were collected from 10 trigger fingers during extension.
Main Results:
- Sudden joint release occurred at the distal and proximal interphalangeal (PIP) joints, with MCP joint extension beginning early.
- Extensor tendons required approximately 1.54 times the force of the flexor tendons to overcome catching at PIP and MCP joints.
- Flexor digitorum profundus tension exceeded flexor digitorum superficialis (FDS) tension in most cases.
Conclusions:
- The developed biomechanical model offers a clearer understanding of trigger finger tendon forces.
- Quantitative insights into trigger finger movement characteristics can improve etiology understanding.
- Findings support the development of enhanced assessments and treatments for trigger finger.
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