Scapholunate Dissociation
What is it: Scapholunate dissociation occurs when the ligaments between the scaphoid and lunate are disrupted, usually due to an injury from a fall on an outstretched hand.
How does it present: The patient may present with wrist pain or difficulty with grasping objects and grip strength.
Common exam findings: The exam may show tenderness over the scapholunate junction. They may also have a positive Watson's Test or Shuck Test.
Tests and treatment: A widening of the space between the scaphoid and lunate to greater than three millimeters on x-ray is indicative of this injury. This abnormality may be best seen on the PA view of the wrist done in the position of a fist in a slightly flexed pose. This widened space has been called the "Terry Thomas" sign named after an actor who had a large gap between his two front teeth. If the x-rays do not show evidence of the injury, but it is strongly suspected on physical exam, an MRI arthrogram of wrist would better identify ligament injury. Referral to orthopedics is indicated if this injury is found.