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In vivo motion of the scaphotrapezio-trapezoidal (STT) joint
S E Sonenblum1, J J Crisco, L Kang
1Division of Engineering, Brown University, Providence, RI, USA.
Journal of Biomechanics
|March 30, 2004
Summary
The scaphotrapezio-trapezoidal (STT) joint exhibits subtle yet significant relative motion between the trapezoid and trapezium bones. This finding suggests a more complex articulation than previously modeled, impacting wrist biomechanics.
Area of Science:
- Orthopedics
- Biomechanics
- Anatomy
Background:
- Previous models simplified the scaphotrapezio-trapezoidal (STT) joint, treating the trapezium and trapezoid as a single unit.
- This simplification raised questions about the necessity of distinct articulating surfaces and its impact on overall wrist motion.
Purpose of the Study:
- To investigate the in vivo motion between the trapezium and trapezoid bones within the STT joint.
- To determine if there is relative motion between these carpal bones during wrist movements.
Main Methods:
- Utilized a markerless bone registration technique for in vivo analysis of 20 wrists from 10 subjects.
- Analyzed centroid spacing, displacements, kinematics, and postures of the trapezium and trapezoid relative to the scaphoid.
Main Results:
- Gross STT joint motion aligns with previous in vitro findings.
- Trapezium and trapezoid motion magnitude varies with wrist movement direction.
- Statistically significant, albeit small, relative motions (rotations and displacements) were observed between the trapezium and trapezoid.
Conclusions:
- The STT joint is more mobile and exhibits complex motions than previously understood.
- The findings challenge simplified models and highlight the nuanced articulation of these carpal bones.