Clinical Presentation of Jersey Finger
Jersey finger presents with inability to actively flex the distal interphalangeal (DIP) joint of the affected finger following forced hyperextension of a flexed digit, most commonly affecting the ring finger (80% of cases). 1
Key Clinical Features
Mechanism of Injury
- Classic mechanism: Forced hyperextension of the DIP joint while the finger is actively flexing, typically when gripping an opponent's jersey during contact sports 2, 3
- Occurs when the flexor digitorum profundus (FDP) tendon avulses from its insertion at the base of the distal phalanx 1
- The ring finger is most vulnerable due to its anatomical position and relatively weaker FDP tendon 3
Physical Examination Findings
- Loss of active DIP joint flexion - the pathognomonic finding 4, 5
- Patient cannot flex the fingertip while the proximal interphalangeal (PIP) joint is held in extension
- Tenderness along the flexor tendon sheath, particularly in the palm or at the base of the affected finger
- Palpable tender mass may be present in the palm if the tendon has retracted proximally 4
- The finger may rest in slight extension compared to adjacent digits
Associated Findings
- Bony avulsion fragments may be present and visible on radiographs - these can be small or, rarely, involve up to 80% of the distal phalanx 6, 7
- Swelling and ecchymosis along the volar aspect of the finger
- Pain with passive extension of the DIP joint
Diagnostic Approach
Initial Imaging
Plain radiographs are mandatory to identify avulsion fractures, which occur in approximately 25-75% of cases and significantly influence surgical planning 1. Standard 3-view hand radiographs should be obtained.
Advanced Imaging
MRI is the ideal modality for evaluating jersey finger when surgical planning is needed, as it determines 1:
- Level of tendon retraction (critical for surgical approach)
- Quality of the tendon stump
- Associated pulley injuries
- Presence of peritendinous adhesions in delayed presentations
Clinical Pitfalls
Common Diagnostic Errors
- Delayed presentation is common - patients may present weeks after injury, particularly in non-athletic trauma 4, 6
- The injury can be mistaken for a simple "jammed finger" if DIP flexion is not specifically tested
- Proximal ruptures can occur at the lumbrical origin rather than at the distal insertion, mimicking jersey finger but requiring different surgical exposure 5
Critical Timing Considerations
Early diagnosis is essential because:
- Tendon retraction increases with time, making repair more difficult 4
- Adhesion formation occurs rapidly, complicating surgical retrieval 4
- Optimal surgical outcomes require intervention within 7-10 days, though successful repairs have been reported up to several weeks post-injury 4
Examination Technique
To avoid missing the diagnosis:
- Isolate DIP joint testing: Hold the PIP joint in full extension and ask the patient to flex only the fingertip
- Compare with the contralateral hand
- Test each finger individually, as patients may compensate using adjacent digits
Rare Variants
Type IV jersey finger combines FDP avulsion with a fracture of the volar base of the distal phalanx 7. Double jersey finger involves simultaneous avulsion of both FDP and flexor digitorum superficialis tendons, significantly complicating management and prognosis 2.