The scaphoid shift test aka midcarpal shift test is a variation of the Watson Test for scaphoid instability. A positive test can be caused by scapholunate ligament laxity or injury.
The Watson test evaluates scaphoid instability as the wrist is moved from radial to ulnar deviation (it’s not an “active” test)
To do the scaphoid shift test (as described by Lane in 1993)
Use the same hand as the patient’s affected hand (suspicious of a right scaphoid problem? Use your right hand to test)
Place your hand on the patient’s so that your thumb is over the volar surface of the scaphoid tubercle (the distal pole). Don’t apply any pressure (remember this area is probably at least a little sore and you want to remain friends for now)
Gently move the wrist through ulnar/radial deviation (you can be fancy and consider this your Watson Test) and flexion/extension to relax the patient
With the patient’s wrist in neutral extension and neutral (or slight radial deviation), forcefully and quickly push the scaphoid tubercle in the dorsal direction
At this point, the patient is likely no longer your friend
Note the degree of shift, any crepitus or clunk, and pain evoked.
Suppurative (infectious) flexor tenosynovitis is a medical emergency because the tendon sheath is a closed space and too much swelling can lead to compartment syndrome and necrosis.
* You can’t really get these complications in extensor tendons as it is an open space (no tendon sheath)
There are 4 cardinal signs of flexor tenosynovitis (Kanavel’s Signs)
Tenderness along the whole tendon sheath (late sign)
Finger held in flexion
Fusiform swelling (sausage finger)
Pain with passive extension *this is the earliest finding
It is usually caused by some sort of inoculation, but this can be something very small and the patient may not be aware that he/she had ever been injured (can also be caused by local or hematogenous spread). It’s not unreasonable to get an x-ray to rule out other things and if there’s a fever or they seem very unwell, you can do blood cultures. You also probably want to start the patient on some broad spectrum antibiotics such as vancomycin + ciprofloxacin (or ceftriaxone).
Treatment is tendon sheath drainage and debridement as well as antibiotics.