AKA infected tenosynovitis. These are bad news; the flexor sheaths in the hand are a closed continuous system; if they get infected, the swelling can lead to necrosis, necrotising faciitis, and osteomyelitis.
Common causes include animal bites, puncture wounds, IV drug use, and wounds exposed to fresh or salt water. Scarily, the case report given by this article describes a case in which the wound occurred 22 months previously. The GP referred the man to an urgent, but not same-day, clinic, and fortunately the consultant happened to be going through the letters the same day and spotted the urgency. (Which, by the way, was apparently due to the GP documenting everything so well, so useful lesson there.)
The four cardinal signs are known as the Kanavel signs:
- An exquisite tenderness specifically over the sheath. (From the picture they gave, this seems to run from just proximal to the MCP joint to just distal to the DIP joint.)
- The finger sits in a resting flexed posture.
- Extension of the finger is exquisitely painful, more so at the proximal end.
- Fusiform swelling (I had to look this up; ‘fusiform’ means ‘spindle-shaped’; wide in the middle, tapering at the ends) of the whole finger.
Temperature isn’t very helpful; fever is frequently absent.
Get the patient urgently to a hand surgery department, and advise them to keep the hand elevated meanwhile, to minimise swelling.
Bottom line? When it comes to hands, deep wound + signs of infection = speak to orthopaedics pronto. I think that’s good advice regardless of the specifics. (Also, hooray for Consultant Connect.)
(BJGP, June 2019)