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A Comparative Study of Thumb Metacarpal Morphology and Shape Categorization.
Gretchen M Pavelich1, Kyle R Brena1, Jared D Heinze1
1Vail-Summit Orthopaedic Foundation, Vail-Summit Orthopaedics and Neurosurgery, Vail, CO.
The Journal of Hand Surgery
|December 23, 2021
Summary
A new biplanar thumb metacarpal (MC) head shape, distinct from flat and round types, has been identified. This triangular shape may influence thumb joint motion and injury risk.
Area of Science:
- Orthopedics
- Anatomy
- Radiology
Background:
- The morphology of the metacarpal (MC) head influences the biomechanics of the metacarpophalangeal (MCP) joint.
- Previous classifications have primarily described flat and round MC head shapes.
Purpose of the Study:
- To describe the novel biplanar thumb MC head shape.
- To differentiate this shape from existing flat and round MC head classifications.
Main Methods:
- Retrospective analysis of lateral thumb radiographs from 210 patients (age 18-75).
- MC heads classified as flat or round based on a ratio of articular surface dimensions.
- Identification of MC heads not fitting flat or round criteria.
Main Results:
- Out of 210 participants, 113 had round, 79 had flat, and 18 had biplanar MC head shapes.
- A subset of MC heads could not be classified as flat or round due to measurement challenges.
- The biplanar shape was characterized as triangular with two converging planes.
Conclusions:
- A distinct biplanar MC head shape has been identified.
- This shape presents unique morphological characteristics, differing from flat and round types.
- Further research is needed to understand the clinical implications of MC head shape on joint function and injury patterns.
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