Article
Ligament constraint of the first carpometacarpal joint
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Authors
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Wan Mohd Radzi Rusli
- Bioengineering Department, Imperial College London, London, United Kingdom
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Eushaa Mirza
- Bioengineering Department, Imperial College London, London, United Kingdom
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Sarah Tolerton
- Department of Hand Surgery, Chelsea and Westminster Hospital, London, United Kingdom
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Sarah Yong
- Department of Hand Surgery, Chelsea and Westminster Hospital, London, United Kingdom
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Riem Johnson
- Department of Hand Surgery, Chelsea and Westminster Hospital, London, United Kingdom
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Maxim Horwitz
- Department of Hand Surgery, Chelsea and Westminster Hospital, London, United Kingdom
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Angela Kedgley
- Bioengineering Department, Imperial College London, London, United Kingdom
| Published: | February 6, 2020 |
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Outline
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Objectives/Interrogation: The objective was to determine the role of the ligaments surrounding the first carpometacarpal (CMC) joint in maintaining stability of the joint.
Methods: Eleven specimens (mean = 49.2 years; 5 right hands and 6 left hands) were used in this study. The first and second metacarpals, trapezium and trapezoid were removed from each specimen, taking care not to violate the first CMC joint capsule. Each of the first CMC joints was oriented in neutral using a personalised 3D-printed jig. The distal end of the first metacarpal was fixed in a specimen holder using polymethylmethacrylate. Trapezium, trapezoid and the proximal end of the second metacarpal were fixed in the similar manner. An Instron testing machine equipped with a customised jig was used to apply external loads to the specimen. Translation of the first CMC joint was measured using linear variable differential transformers. Each specimen was tested during intact and ligament sectioning conditions. Four ligaments were included in the sequential sectioning - anterior oblique ligament (AOL), ulnar collateral ligament (UCL), intermetacarpal ligament (IML) and dorsal radial ligament (DRL). For each condition, load was applied to the specimen in four different directions - volar-dorsal (VD), dorsal-volar (DV), radial-ulnar (RU) and ulnar-radial (UR) - while the joint was compressed with 10N to maintain contact of the articular surfaces. The position of the joint in the intact state was taken as the baseline.
Results and Conclusions: Friedman tests indicated significant differences in the translation of the first CMC joint after the ligaments were sectioned, except in the dorsovolar direction when load was applied in both VD and UR directions. Post-hoc analysis showed that when load was applied in the VD, DV and RU directions, there were significant differences (p<0.008) in the translation of the joint after each of the ligaments were cut (Figure 1 [Fig. 1]).
The absence of the DRL can cause instability of the first CMC joint in the dorsovolar direction. This can cause high stress at the interface between the volar beak of the first metacarpal and trapezium.
