“Don’t pull my finger!” – a case of flexor tenosynovitis.

Resident Clinical Pearl (RCP) – July 2018

Mandy Peach – FMEM PGY3, Dalhousie University, Saint John NB

Reviewed by Dr. David Lewis

You are working a rural ED and a 70 yo male presents with an injury to his right hand about one week ago. He has no known past medical history, is widowed and lives alone. He has no family doctor; a family member made him come in.

In triage he denies any major discomfort in the finger, and has taken nothing for pain. However he has noticed it is increasing in size, becoming more red and even black in places.

Vital signs show he is hypertensive, but otherwise afebrile with a normal heart rate.

You walk into the room to do the assessment and immediately your eyes are drawn to his hand:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WHOA.

As you get further history it turns out the injury was a rusty nail to the digit – it just keeps getting better.

You are worried about an infectious flexor tenosynovitis – a can’t miss diagnosis. This is when purulent fluid collects between the visceral and parietal layers of the flexor tendon¹. This infection can rapidly spread through the deep fascial spaces. Direct inoculation, like this penetrating injury, is the most common cause¹.

4 clinical signs of tenosynovitis – Kanavel’s signs

• ‘sausage digit’ – uniform, fusiform swelling
• Digit is held in flexion as the position of comfort
• Pain with passive extension
• Tenderness along the tendon sheath

Figure 1: Sketchy Medicine – Flexor Tenosynovitis http://sketchymedicine.com/2012/10/flexor-tenosynovitis-kanavels-signs/

 

As you can imagine this guy had all 4 signs – slam dunk diagnosis, with a little gangrene at the tip to boot. But the diagnosis isn’t always clear cut, and some of these are late signs of infectious flexor tenosynovitis. Patients may present earlier in the course of illness, so what can we use to help diagnose this condition? PoCUS of course!

Place a high frequency linear probe at the wrist crease where you should visualize flexor tendons overlying carpel bones.

Figure 2: Normal flexor tendons (yellow) and carpel bones in transverse plane¹

In infectious flexor tenosynovitis you would see anechoic edema and debris in the flexor tendon sheath, and potentially thickening of the synovial sheath. You can assess in both longitudinal and transverse planes.

Figure 3: Transverse (A) and Longitudinal (B) images showing edema in flexor tendon sheath¹.

 

Treatment:

So the most common bug that causes these infections is Staphylococcus, however they can be polymicrobial². Broad spectrum coverage is required – think ceftriaxone or pip tazo. If there is concern for MRSA than vancomycin would be indicated.

But let’s remind ourselves – he had exposure to a rusty nail – you must cover Pseudomonas as well.

We chose ceftriaxone and ciprofloxacin, administered a tetanus (he never had one before) and urgently contacted plastics. He stayed overnight in the rural ED and was transferred out the next morning for OR. Unfortunately, he did have up having the digit amputated but he recovered well.

 

Take home message: Flexor tenosynovitis is a surgical emergency – examine for Kanavel’s signs. Ultrasound can be helpful in confirming diagnosis in the right clinical context. Cover with broad spectrum antibiotics, consider MRSA or Pseudomonas coverage if indicated. Urgent plastics referral needed.

 

References:

1. Padrez, KP., Bress, J., Johnson, B., Nagdev, A. (2015). Bedside ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department. West J Emerg Med; 16(2): 260-262.
2. Flexor Tenosynovitis (Karavel’s signs). Sketchy Medicine. Retrieved from http://sketchymedicine.com/2012/10/flexor-tenosynovitis-kanavels-signs/ June 12, 2018.
3. Tintinalli, JE. (2016). Flexor Tenosynovitis (8th ed.) Tintinalli’s Emergency Medicine: A Comprehensive Study Guide (page 1922). New York: McGraw-Hill.