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.
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
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.
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
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.
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