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Updated: Dec 8, 2025
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Three-Dimensional Finger Motion Tracking during Needling: A Solution for the Kinematic Analysis of Acupuncture Manipulation
Published on: October 28, 2021
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Flexion Angles of Finger Joints in Two-Finger Tip Pinching Using 3D Bone Models Constructed from X-Ray Computed
Satoshi Shimawaki1, Yoshiaki Nakamura1, Masataka Nakabayashi1
1Mechanical Systems Engineering Course, Department of Fundamental Engineering, Utsunomiya University, Tochigi 321-8585, Japan.
Applied Bionics and Biomechanics
|September 23, 2020
Summary
Analyzing two-finger tip pinching reveals that the thumb
Area of Science:
- Biomechanics
- Robotics
- Hand Surgery
Background:
- Two-finger tip pinching is essential for object manipulation.
- Designing effective electric prosthetic hands requires understanding hand joint mobility.
Purpose of the Study:
- To identify highly mobile joints during two-finger tip pinching.
- To measure joint flexion angles across different grip diameters.
Main Methods:
- Computed tomography (CT) imaging of ten participants' hands.
- Creation of 3D bone models for joint angle measurement.
- Analysis of hand postures during pinching of varying cylinder diameters (2, 10, 30 mm).
Main Results:
- Index finger proximal interphalangeal and metacarpophalangeal joint flexion angles decreased with increasing cylinder diameter.
- Distal interphalangeal joint of the index finger and all thumb joints (flexion/rotation) remained constant regardless of cylinder size.
- Thumb posture is fixed, while index finger posture adapts to object size during pinching.
Conclusions:
- Electric prosthetic hand design for two-finger tip pinching can focus on index finger joint actuation.
- Thumb joint mobility is not a primary factor in adapting to different object sizes during this grip.
- This research provides key insights for developing more functional prosthetic devices.
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