Jersey Finger

Etiology

The distal phalanx suffers exposure to substantial forces during pull-away mechanisms. Flexor digitorium distal avulsion commonly presents in young athletes, especially in contact sports.[4] The mechanism of injury typically results from forceful extension of a flexed digit. A common example is grabbing the jersey of an opposing player to make a tackle during American football or rugby, resulting in a forced extension of the flexor digitorium profundus tendon during maximum contraction of the muscle belly.

Epidemiology

Finger injuries account for 38% of all acute upper extremity injuries.[5] A recent study showed that tendon injuries in the hand occur at a rate of 33.2 per 100000 person-years. Only 4% of these injuries occur in flexor tendon zone I (distal to the insertion of flexor digitorum superficialis on the middle phalanx).[6]

Jersey finger can happen in any digit and represents the most common closed flexor tendon injury.[7] The ring finger is the most common involved digit (75% of the cases). When performing gripping, the ring fingertip becomes the most prominent digit in the vast majority of the population. Also, the ring finger is bound on both sides by lumbrical muscles, making it more prone to hyperextension injuries. There are reports that the load to failure of the FDP tendon needed for the ring finger is much less than other digits.[8]

Pathophysiology

DIP joint hyperextension during maximal FDP muscle belly contraction (clenched fist) leads to failure. The injury occurs to the distal tendon insertion at the base of the phalanx as this area represents its weakest point.[9]

History and Physical

It is crucial to have a high level of suspicion for a jersey finger in athletes with finger pain and to associate these injuries to sport-related trauma. Pain and tenderness of the volar aspect of the injured finger are the common presentations. In a resting position, the injured finger will usually remain in extension compared to the other digits. Sometimes, the retracted tendon can be palpated proximally to the avulsion. Flexion of the DIP joint is absent. Grip and flexion against resistance will usually cause pain.

Evaluation

Although physical examination should be enough to reach the diagnosis of jersey finger, X-rays and ultrasound may play an important role. Plain radiographs are mandatory to rule out fractures. Antero-posterior and lateral views may reveal a bony fragment, if present. Ultrasound may be useful to asses tendon anatomy in cases without fracture. In chronic injuries, ultrasound becomes crucial to evaluate tendon retraction and guide further treatment.

MRI is rarely performed but can be used to determine the increased tendon-bone distance more accurately.[10]

Treatment / Management

The typical treatment for jersey finger injuries is surgery. Early treatment is essential to restore blood supply and function. Flexor tendons nourish themselves from blood vessels located inside the mesotendon (long and short vincula). Conservative treatment has been minimal reporting in cases of high-risk surgical patients.[11][12](B3)

Surgical Management

• Acute: within 3 weeks after injury.
  • Without fracture: direct tendon repair or tendon reinsertion (mini-suture anchor).
  • Fracture fragment: calls for open reduction and internal fixation (mini-screws, wires). Currently, suture anchors are being used in cases of bony avulsions as well. 

There are multiple, described proven treatment techniques for acute injuries. None of these seem to be significantly superior to the others.[13]

• Chronic: over 3 months after injury.
  • Two-stage tendon grafting (if the full range of motion is present).
  • DIP joint arthrodesis (if chronic stiffness is present). Joint arthrodesis requires careful discussion with each patient. The distal interphalangeal joint motion may be essential for some patients (occupation and hobbies), and tendon reconstruction may become a valid alternative. Unfortunately, tendon reconstruction requires a significant time commitment from the patient to achieve a successful long-term rehabilitation outcome.

Differential Diagnosis

Jersey finger injuries may get dismissed as minor sprains or phalanx fractures. There are several reports of athletes “playing through” the injury, even at a competitive level.[3]

Treatment Planning

The surgical approach in the presence of a bony avulsion is challenging. Preoperative planning should consider fragment size, fragment displacement, and soft tissue repair.[14]

Treatment of a jersey finger should take into account each patient’s goals and expectations. Treatment in sport-related injuries may be influenced by the athlete’s playing position and the level of competition.

Staging

Jersey Finger Injury Classification[9]

• Type 1: Severe avulsion. The tendon retracts into the palm. Blood supply is severely compromised.
• Type 2: The tendon retracts but remains at the A3 pulley (proximal interphalangeal joint).
• Type 3: The avulsion includes a bony fragment. Both tendon and fracture fragment remain at the A4 pulley.
• Type 4: Rare injury, defined by the presence of both a fracture and a tendon avulsion from the bony fragment. The tendon can retract into the palm. 

Prognosis

Early diagnosis leads to expedited treatment with excellent functional outcomes. Surgery within 10 days after the injury correlates with excellent patient-reported outcomes.[15]

Patients may return to sports with both full active functional range of motion and the absence of pain (approximately 8 to 12 weeks).

Functional consequences of impaired DIP joint motion includes loss of dexterity and loss of pinch strength.[3]

Postoperative functional and aesthetic results depend on accurate reduction, repair quality, and an adequate rehabilitation protocol. Prevention of scar contracture formation is crucial to maintain finger function.[16][17]

Complications

A tendon advancement of over 1 cm carries the risk of quadriga. The term quadriga refers to an inability to flex the digits adjacent to the involved digit from increased tension over the repaired tendon.[18]

Other surgical complications include infection, skin necrosis, tendon repair rupture, nail matrix injury, and adhesions.[19][20]