What is the diagnosis?

The diagnosis is jersey finger (also known as rugby finger), which is an avulsion injury of the flexor digitorum profundus (FDP) tendon from its insertion on the distal phalanx.  

• Pearl: Tendon injuries in the hand are uncommon, occurring at a rate of 33.2 per 100000 person-years. [1]Only 4% of these injuries are found to occur in the flexor tendon zone (zone I) of the hand, or distal to the insertion of the flexor digitorum superficialis on the middle phalanx. [2] Jersey finger is the most common closed flexor tendon injury.  

Image 2. Image courtsey of Rasuli B, Lustosa L, Knipe H, Radiopaedia.org, rID:75425

(https://radiopaedia.org/articles/75425)

What is the mechanism of injury?

Jersey finger occurs when there is a forced extension of a flexed digit, for example when a player grabs an opponent’s jersey during a tackle. The FDP tendon is forcibly extended during maximum contraction of the muscle belly. 

• Pearl: the ring finger is the most commonly injured (up to 75% of cases). [3] This is likely because it is the longest when gripping, and is bordered by lumbrical muscles on both sides, making it more prone to hyperextension injuries. The ring finger also requires a smaller load to failure of the FDP than the other digits do. 

What physical exam findings are expected?

The patient will likely be unable to actively flex the DIP. When asked to make a fist, the affected digit will remain in extension. The patient may complain of pain at the volar aspect of the injured finger, and may have pain with flexion against resistance. At times, the retracted tendon can be palpated proximally to the avulsion. 

Which imaging modalities can be used?

Ultrasound can be used to determine the anatomy of the injured tendon and evaluate the degree of tendon retraction. [4] Outpatient MRI can also be used to determine the tendon-bone distance for operative planning. 

• Pearl: Jersey finger is diagnosed by physical exam and history. An x-ray must be obtained to rule out concomitant fracture. 

What is the management in the ED?

Obtain AP and lateral views of the finger to assess for concomitant fracture. Splinting is appropriate in a position of comfort in slight flexion. [5]

When do you consult Orthopedics?

Consult orthopedics in the ED for open fracture or neurovascular compromise. Otherwise patient should have an orthopedic consult outpatient urgently. The treatment for jersey finger is surgery within 7-10 days for the most favorable outcomes because as the tendon contracts it becomes less viable.[6] If you have orthopedics available, it would be beneficial to let them know about the patient to facilitate close follow up.