The ligament of Testut (radioscapholunate ligament, RSL) is a structure on the palmar surface of the radiocarpal joint running from the radial styloid to the scaphoid-lunate interosseous interval. Despite its name, it is now recognised as a vascular structure (neurovascular bundle carrying blood to the scapholunate interosseous ligament) rather than a true structural stabilising ligament. It does not contribute meaningfully to wrist stability.
Carries vascular supply to the scapholunate interosseous ligament rather than functioning as a mechanical stabiliser. Historically considered a palmar radiocarpal ligament but now reclassified as a neurovascular fold.
Understanding that the ligament of Testut is not a true stabilising ligament has important surgical implications: it can be divided safely during arthroscopic wrist procedures to improve visualisation without compromising wrist stability, whereas dividing adjacent true wrist ligaments such as the radioscaphocapitate would cause instability. On MRI arthrography, the ligament of Testut may be mistaken for a pathological structure. Its recognition during wrist arthroscopy, where it appears as a soft tissue fold in the palmar radiocarpal recess, prevents unnecessary conservation of a non-structural element.
The ligament of Testut can be safely divided during wrist arthroscopy to improve access to the palmar radiocarpal joint and the scapholunate interval, unlike true radiocarpal ligaments such as the RSC and long RL which must be preserved; its vascular nature means it bleeds when cut but its division causes no instability.
