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.