Our patient has wrist pain because of a scapholunate ligament tear. This is the most common ligament injury in the wrist. Normally the scaphoid and lunate move together but when a scapholunate tear occurs the scaphoid flexes and the lunate extends. This causes pain in the wrist. There are four classes of injury: 1 occult seen only on MRI, 2. Dynamic showing up on stress xrays or MRI, 3. Static visible on plain films as a gap between the scaphoid and lunate and 4. Advanced collapse where the ligament is completely torn and the injury has been there for years causing arthritis.
The pt may complain of pain while doing pushups or any activity that loads the wrist. A stress xray may be performed by making a tight fist for one xray and then bending the wrist towards the small finger for another xray and then bending toward the thumb for a final xray. A gap will occur at the scapholunate junction during activity if there is an injury. If there is a widening of 3-4 mm this is diagnostic and referred to as the Terry Thomas sign named for a British comedian who had a gap between his two front teeth.
World class tennis players are at risk for these wrist injuries . It is estimated that serves pack rotational velocities of 1,500 degrees per second which is nearing the limits of human physiology. Richard Berger of the Mayo clinic is currently operating on microscopic tears of the scapholunate ligament which are not even visible on MRI in these elite athletes so continued pain is a reason for referral even if there is no radiologic abnormality. These injuries also occur in the more common “fall on outstretched arm” injuries that we see associated with distal radius fractures.
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