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Mallet Finger vs Jersey Finger

Compare mallet finger and jersey finger injuries, including extensor vs flexor tendon anatomy, X-ray findings, MRI clues, and treatment urgency.

Analyze My Hand
Editorial policyEducational. Not a diagnosis.

Key Takeaways

  • Mallet finger is an extension problem; jersey finger is a flexion problem
  • Jersey finger can be time-sensitive because the flexor tendon may retract
  • Normal X-rays do not exclude a tendon-only injury
Glass finger in side view with the extensor and FDP flexor tendons glowing where they attach to the fingertip bone
Two tendons control the fingertip: the extensor on the back straightens it, and the FDP flexor on the palm side bends it. Mallet finger injures the first, jersey finger the second. Educational illustration, not a medical scan.

Mallet finger and jersey finger both affect the fingertip, but they are opposite tendon problems. Mallet finger affects active extension. Jersey finger affects active flexion.

The Fast Difference

  • Mallet finger: the fingertip droops and cannot actively straighten
  • Jersey finger: the fingertip cannot actively bend
  • Mallet injury is on the extensor side near the back of the DIP joint
  • Jersey injury is on the flexor side where the FDP tendon inserts
Two glass fingers compared: mallet finger with a drooping tip and torn extensor, jersey finger with a retracted flexor tendon
Left: mallet finger, where the extensor tendon on the back of the DIP joint separates and the fingertip droops. Right: jersey finger, where the FDP flexor tendon pulls away from the palm side and can retract, so the fingertip cannot bend. Educational illustration, not a medical scan.

How Imaging Helps

X-rays look for bony avulsion fragments and joint alignment. MRI or ultrasound can directly assess tendon continuity and retraction, especially when the X-ray is normal but the exam shows loss of active motion.

Frequently Asked Questions

Which injury is more urgent?

Jersey finger is often treated as more time-sensitive because the flexor tendon can retract. Mallet finger also deserves prompt assessment, especially with a large bony fragment or DIP subluxation.

Can both injuries happen without a fracture?

Yes. Both can be pure tendon injuries. That is why active fingertip bending and straightening are important parts of the exam, even when X-rays do not show a clear fracture.

Sources

  1. Leddy JP, Packer JW. Avulsion of the profundus tendon insertion in athletes. J Hand Surg Am. 1977;2(1):66-69.
  2. Bendre AA, Hartigan BJ, Kalainov DM. Mallet finger. J Am Acad Orthop Surg. 2005;13(5):336-344.
  3. Lin JD, Strauch RJ. Closed soft tissue extensor mechanism injuries (mallet, boutonniere, and sagittal band). J Hand Surg Am. 2014;39(5):1005-1011.
  4. Weintraub MD, Hansford BG, Stilwill SE, et al. Avulsion injuries of the hand and wrist. Radiographics. 2020;40(1):163-180.

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Related Conditions

Mallet FingerJersey FingerBoutonniere Deformity

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Medical Disclaimer: This page is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. AI-generated analysis may contain errors. Always consult a qualified healthcare professional for medical decisions. Full Disclaimer