Désaxation scapholunaire : physiopathologie et orientations thérapeutiques

The interosseous scapholunate ligament (IOSLL) is the main stabilizer of the scapholunate (SL) couple but a static instability can appear only in the event of an associated injury of the extrinsic ligaments. Thus, SL dissociation covers a broad spectrum in which only static instability leads with certainty to osteoarthritis. Classically described as a rotatory subluxation of the scaphoid with DISI collapse, static SL instability manifests itself as a complex deformity with dorsolateral subluxation of the unit formed by the scaphoid and the distal carpal row. This deformity explains the dorsolateral radioscaphoid conflict and capitolunar decentering that is the origin of the radioscaphoid and midcarpal osteoarthritis that later appears. It is only within the first 4 to 6 weeks that a repair of the IOSLL, possibly associated with a capsulodesis, makes it possible to expect a good result and can prevent osteoarthritis. Beyond that time, no soft tissue procedure will modify the natural history of the condition. For us, surgery is indicated only for acute injuries and for symptomatic chronic instabilities. Before the occurrence of osteoarthritis, with newfound knowledge of the medium-term results of capsulodesis, it seems reasonable to favour a limited fusion. But in the event of failure, the patient is likely to remain in pain even after a total fusion. It is thus not aberrant to perform a capsulodesis in a sedentary person but it is necessary to inform the patient that osteoarthritis will occur. After occurrence of osteoarthritis, if it is symptomatic, proximal row carpectomy, SLAC procedure, total wrist fusion and denervation, can be considered, depending on the stage, the mobility of the wrist and the wishes of the patient. Denervation of the wrist can give good results with few risks, and does not jeopardize the results of a subsequent procedure.