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The Best in FOAM Education

  • Sonika Raj MD, MS

When the Tendon is Tender: Flexor Tenosynovitis

A 50-year-old, right-handed, male, construction worker with diabetes presents with one day of rapid-onset right index finger pain, swelling, and redness. He states it started shortly after he accidentally slammed it against a slab of drywall. Vital signs are notable only for a fever. He refuses any kind of exam (beyond inspection) due to extreme pain whenever his finger is moved. Based on the photo below, what’s at the top of your differential?

This is flexor tenosynovitis! This disease is defined as inflammation/infection of the flexor tendon and its synovial sheath due to trauma, IV drug use, fresh/salt water, plants, animal/human bites, contiguous spread from a nearby infection, or hematogenous spread (i.e. from gonorrhea or Mycobacteria. Remember to look for skin lesions on the actual finger.)

The classic criteria used to identify flexor tenosynovitis are the Kanavel criteria, which you may recall using the mnemonic PEST:

  • flexed Position

  • pain with passive Extension

  • “fusiform” Swelling (or Sausage digit)

  • Tenderness along the flexor sheath.

Flexor tenosynovitis is a surgical emergency because any delay to care increases the risk of adhesion formation within the finger. This puts the patient at risk of loss of digital function, tendon necrosis/rupture, worsening infection, and even digit loss. Given this incredible risk of morbidity, how do you manage this patient?

First, consult a hand service (orthopedics, plastic surgery, etc.) for an emergent incision and drainage. This is definitive treatment and should be sought as soon as the diagnosis is made.

Next, start IV antibiotics. Some good choices (depending on the prevalence of MRSA in your area) including vancomycin and piperacillin-tazobactam, ampicillin-sulbactam, and cefoxitin. If you obtain any discharge spontaneously, send it for gram stain and culture. Instruct the patient to elevate the extremity.

Lastly, this patient requires admission for continued IV antibiotics and close observation.

On that note, what happened to our patient? Immediately after his initial evaluation, orthopedics was consulted and the patient was started on ampicillin-sulbactam. The orthopedics resident performed a bedside incision and drainage, after which the patient was admitted to a medical service for five days. At that time, his symptoms had greatly improved and he was discharged on oral antibiotics.

Take-Away #1:

Flexor tenosynovitis has a range of causes that include trauma, IVDA, fresh/salt water, plants, animal/human bites, contiguous spread, and hematogenous spread (don’t forget gonorrhea).

Take-Away #2:

Remember the Kanavel criteria using the mnemonic PEST: flexed Position, pain with passive Extension, fusiform” Swelling (or Sausage digit), and Tenderness along the flexor sheath.

Take-Away #3:

Consult a hand service and start empiric antibiotics early.


Sonika Raj MD, MS is a current third year resident at Stony Brook Emergency Medicine.


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