scapholunate dissociation
A wrist injury involving disruption of the ligamentous connection between the scaphoid and lunate bones, leading to carpal instability.
Full Definition
Scapholunate dissociation is a common form of carpal instability resulting from injury to the scapholunate interosseous ligament, which normally maintains proper alignment between the scaphoid and lunate bones. This condition can range from partial ligament tears to complete dissociation with rotatory subluxation of the scaphoid. Patients typically present with dorsal wrist pain, weakness of grip, and a positive Watson test. Radiographically, it may present as widening of the scapholunate interval (Terry Thomas sign) and increased scapholunate angle. If left untreated, it can progress to scapholunate advanced collapse (SLAC) arthritis of the wrist.
Usage
Usage note: Distinguish from SLAC wrist, which is the arthritic consequence of untreated scapholunate dissociation.
In Context
- "The patient's chronic wrist pain was attributed to scapholunate dissociation with a widened scapholunate interval of 5mm on PA radiographs." — Clinical assessment
- "Arthroscopic examination confirmed complete scapholunate dissociation with a drive-through sign present between the scaphoid and lunate." — Operative report