Sexual dimorphism in the anatomy of the ulnar collateral thumb ligament
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Treatment of ruptured ulnar collateral thumb metacarpophalangeal (MCP) joint ligaments (UCL) necessitate a profound anatomic knowledge for optimal surgical repair in order to preserve range of motion and ensure postoperative joint stability. Therefore, knowledge of the angle between the UCL and the longitudinal axis of the first metacarpal bone could be useful.
In this study 46 ulnar collateral thumb MCP joint ligaments in 15 male and 15 female embalmed anatomic specimens were dissected and the angles between the longitudinal axis of the first metacarpal bone and the proper (PUCL) as well as the accessory ulnar collateral thumb MCP ligament (AUCL) were measured.
In male specimens the angle for the PUCL measured on average 133.5° (±2.35°) and 122.75° (±3.8°) for the AUCL. A significantly different angle was measured for female specimens which showed on average 137.88° (±3.51°) for the PUCL and 128.65° (±4.14°) for the AUCL.
Optimal surgical repair or reconstruction of torn ulnar collateral thumb MCP joint ligaments should aim for an angle of approximately 135° in PUCL and 126° in AUCL in relation to the longitudinal axis of the metacarpal bone. Differences in men and women should be considered if possible.
Level of evidence
IV (anatomic study).
KeywordsUlnar collateral ligament thumb Thumb metacarpophalangeal joint Anatomic sexual dimorphism Collateral ligament thumb
The authors gratefully thank all donors who placed their bodies at disposal by last will and testament to the body donation program of this university. Without their gift anatomic research would not be possible.
None of the authors has a financial interest in any of the products or devices mentioned in this manuscript. This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Compliance with ethical guidelines
Conflict of interest
M.F. Vierhapper, G.K. Muschitz, S. Hacker, S.E. Boesmueller, M. Pretterklieber, and H.B. Kitzinger declare that they have no competing interests.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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