Causes / typical injury mechanism: Jersey finger (often called rugby finger in Europe and Australia) refers to the avulsion of the flexor digitorum profundus (FDP) from its distal insertion into the volar aspect of the distal phalanx. This injury typically occurs when the FDP is fully contracting the distal interphalangeal (DIP) joint but the distal phalanx is pushed into extension.

Classic history and presentation: The typically cited event is a player grabbing the jersey of the opponent. The patient will notice immediately that their finger is injured but may play through the injury.

The finger will rest in an extended position with an inability to flex the DIP joint. There may or may not be a palpable FDP tendon. Around 75% of cases involve the ring finger.

Prevalence:

• Age – Jersey finger is usually seen in younger patients playing contact sports.
• Sex / gender – Predominantly male patients.

Risk factors: Risk factors include playing contact sports or activities where the fingers are in a flexed position (eg, rock climbing).

Grade / classification system: The disease is categorized according to the Leddy and Packer classification –

• Type I: FDP has completely retracted into the palm.
  • Blood supply is maintained through the vinculum longus profundus (VLP). The vinculum brevis profundus (VBP) is lost with this type of injury.
• Type II: The FDP tendon is retracted to the proximal interphalangeal (PIP) joint. The VLP remains intact as a blood supply to the tendon, allowing for less urgency of repair.
• Type III: The FDP remains at the level of the DIP joint due to a large avulsion fracture.
• Type IV: Involves both an osseous avulsion fracture off of the distal phalanx and avulsion of the tendon, with retraction of the tendon into the palm.
• Type V: Bony avulsion in combination with an extraarticular or intraarticular fracture of the distal phalanx.