CASE                               24                               

A 34-year-old man presents to the emergency department with pain in his left small finger. He reports that he was cutting meat when his knife slipped and punctured the volar surface of his proximal phalanx. It did not bleed, and he did not seek further medical treatment. He presents with pain in the finger. A diagnosis of flexor tenosynovitis is suspected.

Which of the following is a classic sign of flexor tenosynovitis, as described by Kanavel?

1. A painful finger held in extension

2. Fusiform swelling of the digit

3. Erythema of the digit

4. Pain with axial loading of the digit

5. Tenderness along the lateral aspect of the finger

Discussion

The correct answer is (B). Kanavel’s four cardinal signs of flexor tenosynovitis are intense pain with passive extension, a finger held in flexion, fusiform swelling of the entire digit, and percussion tenderness along the course of the tendon sheath. Erythema is not a cardinal sign of flexor tenosynovitis. Pain with axial loading is suggestive of a septic joint.

Which of the following will most likely rule out flexor tenosynovitis?

1. A normal white blood count without a shift

2. A normal ESR

3. A normal CRP

4. A normal x-ray

5. Painless passive extension

Discussion

The correct answer is (E). The earliest sign of flexor tenosynovitis is pain with passive extension. Normal labs and a normal x-ray cannot rule out flexor tenosynovitis, as the negative predictive value of normal inflammatory markers is low for flexor tenosynovitis.

The patient does not improve on antibiotics. His finger is markedly swollen. He needs surgical decompression, irrigation, and debridement.

Which incision should be avoided?

1. An oblique incision over the A1 pulley and a radially based chevron incision over the A5 pulley

2. A Brunner zigzag incision

3. An ulnar posterolateral midaxial longitudinal incision

4. A transverse incision at the proximal edge of the A1 pulley and a transverse incision at the distal interphalyngeal flexion crease

Discussion

The correct answer is (B). The Brunner incision should be avoided because with severe swelling, skin closure may be difficult and the tendons can then desiccate. Incisions accessing the sheath over the A1 and A5 pulleys are used to access the tendon sheath and perform the incision and drainage. Midaxial incisions are preferred if the swelling of the digit is compromising vascularity in order to relieve the pressure and prevent necrosis of the skin.

The patient refuses surgical intervention. As the infection progresses without surgical treatment, which of the following is unlikely?

1. Tendon necrosis

2. Skin necrosis

3. Osteomyelitis

4. Flexor tenosynovitis of the thumb

5. Paronychial infection

Discussion

The correct answer is (E). Increased pressure secondary to infection can lead to skin loss and tendon necrosis, which may require amputation. A direct extension of the infection to the bone causes osteomyelitis. Infection of the small finger may extend to the thumb in what is called a “horseshoe abscess” as the small finger and thumb tendon sheaths communicate. This may involve other digits, as the communications are quite anomalous. A paronychial infection is unlikely as a direct extension of the flexor tenosynovitis because the infection would have to extend through the distal interphalyngeal capsule joint and into the dorsal tissues.

Objectives: Did you learn...?

Identity the physical examination findings of flexor tenosynovitis? Describe the negative predictive value of normal laboratory findings? Select which incisions are indicated for drainage?

Describe the natural course of untreated flexor tenosynovitis?