Merck Manual

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Flexor Digitorum Profundus (FDP) Avulsion

(Jersey Finger; Rugby Finger; Sweater Finger)


Paul L. Liebert

, MD, Tomah Memorial Hospital, Tomah, WI

Reviewed/Revised Nov 2023

Flexor digitorum profundus avulsion generally occurs at the tendon's insertion at the distal phalanx. The injured finger cannot actively be flexed at the distal interphalangeal joint. X-rays are needed to rule out avulsion fracture. Treatment is with surgery.

The injury occurs primarily in football and other contact sports (eg, rugby). The ring finger is the most injured (75% of cases).

Etiology of Jersey Finger

Flexion of the hand digits is controlled by the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS). The FDP inserts on the distal phalanx and flexes the distal interphalangeal (DIP) joint.

The most classical mechanism of FDP avulsion is that an athlete grips the jersey or shirt of a second athlete, catching the flexed finger, which gets extended forcefully as the second athlete suddenly moves away, rupturing the tendon.

FDP avulsion can avulse a bone fragment.

Symptoms and Signs of Jersey Finger

The injured athlete cannot actively flex the distal interphalangeal (DIP) joint. Palpation of the volar/palmar surface of the fingertip is painful. The affected finger rests in slight extension.

Diagnosis of Jersey Finger

  • X-ray

X-rays are needed to rule out an avulsion fracture of the distal phalanx. Active flexion of the affected distal interphalangeal (DIP) joint must be done or the diagnosis can be easily missed.

Pearls & Pitfalls

  • Test active DIP joint flexion in contact sport athletes who have unexplained pain at the DIP joint, particularly if the resting position is in extension.

Treatment of Jersey Finger

  • Surgery

The treatment of choice is surgical repair done by a hand specialist.

Key Points

  • Jersey finger occurs in contact sports such as football and rugby.

  • To avoid missing the injury, test active distal interphalangeal (DIP) joint flexion of the involved finger.

  • Refer affected patients to a hand specialist for surgical repair.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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