The scapholunate joint is stabilised by both intrinsic ligaments (the scapholunate interosseous ligament, SLIL) and extrinsic ligaments. The dorsal extrinsic stabilisers include the dorsal intercarpal ligament (DIC, from scaphoid to triquetrum via the dorsal ridge) and the radioscapholunate ligament (RSL, Testut ligament). The volar extrinsic stabilisers include the radioscaphocapitate (RSC) and the long radiolunate (LRL). These extrinsic ligaments provide secondary stability when the SLIL is disrupted.
Provide secondary scapholunate stability when the primary intrinsic SLIL is compromised, maintaining scapholunate alignment and preventing progressive DISI carpal collapse.
Scapholunate instability management depends critically on the integrity of the extrinsic ligaments. In partial SLIL tears, intact extrinsic ligaments prevent progressive DISI and allow non-operative management. In complete SLIL tears with intact extrinsics (static SLIL instability), direct repair augmented by dorsal capsulodesis using the DIC ligament may be sufficient. In complete SLIL tears with extrinsic ligament failure (DISI with carpal collapse), four-corner fusion or ligament reconstruction is required. The DIC ligament is the primary target in dorsal capsulodesis procedures.
The dorsal intercarpal ligament (DIC) running from the scaphoid dorsal ridge to the triquetrum is used in dorsal capsulodesis procedures for scapholunate instability, where a DIC-based flap is advanced and anchored to the scaphoid to limit scaphoid flexion and prevent progressive DISI collapse.
