Primary and secondary stabilizers of the scapholunate joint: a systematic review of cadaveric ligament sectioning studies.
Joshua Andrews, Simon Bellringer, Melanie Amarasooriya et al.
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In 30 seconds
This systematic review synthesized cadaveric wrist-biomechanics studies examining changes after carpal ligament sectioning. Across 33 studies involving 406 wrists, the scapholunate interosseous ligament (SLIL) was the primary stabilizer: its sectioning increased the scapholunate gap by a mean of +1.7 mm, the scapholunate angle by +8°, and the radiolunate angle by +3°. The dorsal intercarpal ligament (DIC) was identified as the dominant secondary stabilizer. Combined SLIL-DIC sectioning produced the greatest changes, while dorsal intercalated segment instability occurred only when the SLIL and either the DIC or scaphotrapeziotrapezoid complex were sectioned.
Key findings
- With the SLIL intact, sectioning extrinsic carpal ligaments caused minimal changes in scapholunate gap, scapholunate angle, or radiolunate angle.
- SLIL sectioning increased the scapholunate gap by a mean of +1.7 mm, the scapholunate angle by +8°, and the radiolunate angle by +3°.
- Clenched-fist loading after SLIL sectioning further increased the scapholunate gap (+0.7 mm) and scapholunate angle (+4°).
- Dorsal intercalated segment instability occurred only after combined SLIL and DIC or scaphotrapeziotrapezoid-complex sectioning.
Why it matters
The findings clarify the distinct contributions of intrinsic and extrinsic ligaments to scapholunate stability. Recognizing the SLIL as the primary restraint and the DIC as an important secondary restraint may help clinicians interpret instability patterns and understand why injury to both structures can produce greater biomechanical disruption than isolated ligament sectioning.
What to keep in mind
The evidence comes from cadaveric biomechanical studies and qualitative synthesis; it does not establish clinical outcomes or the effectiveness of reconstruction strategies.