Mallet Finger

Overview

Mallet finger refers to an injury where the extensor tendon at the tip of the finger is damaged
- Results in being unable to extend the DIP joint
This often occurs from a forceful flexion of an extended fingertip, such as being hit by a ball
The result is a drooped fingertip that looks like a mallet/hammer

Anatomy Involved

Terminal extensor tendon: Runs along the backside/dorsal side of the finger and attaches to the distal phalanx
- Is what allows extension at the fingertips to occur
This part of the extensor tendon is what is injured
Sometimes an avulsion fracture occurs simultaneously (part of the distal phalanx pulls off when the tendon is injured)

Causes

A common cause is an object striking the tip of an extended fingertip, forcing it into sudden flexion
- Causes the tendon to tear
Cuts/abrasions

Symptoms

Inability to actively straighten the DIP joint
Fingertip presents in a flexed/drooped position
Pain, swelling, and tenderness at the DIP joint

Prognosis/Timeline

Most mallet fingers are treated non-surgically and have a good prognosis if the strict orthosis protocol is followed by patients
The DIP joint is put into slight hyper-extension and then an orthosis is fabricated that is worn at all times for 6-8 weeks
- Any flexion at the DIP joint during this time can restart the timeline for healing
- Patients usually come in weekly or biweekly to have a new orthosis fabricated
- PIP joint flexion should be encouraged when the orthosis is worn to prevent stiffness in this joint
An orthosis is then worn just at night for another few weeks
Full recovery usually takes 10-12 weeks but extensor lag may linger in some cases (person cannot actively extend their DIP joint but it can be moved to full range passively)

Treatment Ideas

Always ask your fieldwork educator or supervising therapist and review any followed protocols before implementing any of the following

These activities are usually performed once the orthosis is no longer being worn at all times

AROM extension of affected finger

Pegboard with digit extension after each peg placed

Theraputty flatten with finger

Quiz Questions

1. What is mallet finger?

A. A fracture at the distal phalanx

B. An injury to the terminal extensor tendon at the fingertip

C. A torn flexor tendon at the fingertip

D. A dislocated DIP joint

2. Which joint is affected in mallet finger?

A. MCP joint

B. PIP joint

C. DIP joint

D. Nonsense, there is no joint involvement in mallet finger

3. The terminal extensor tendon inserts on which bone?

A. Distal phalanx

B. Proximal phalanx

C. Middle phalax

D. Trapezium

4. What symptom is most characteristic of mallet finger?

A. Tingling in the fingertip

B. Inability to active flex the DIP joint

C. Inability to actively extend the DIP joint

D. Triggering with finger flexion

5. What kind of injury sometimes occurs in addition to the tendon injury?

A. Radial head fracture

B. Avulsion fracture of the distal phalanx

C. MCP joint dislocation

D. Torn lateral band

6. What is a possible lingering issue after recovery from mallet finger?

A. Chronic edema in the finger

B. Numbness in the finger

C. Extensor lag

D. Joint instability at the PIP joint

7. Which of the following statements is true about orthosis use in mallet finger treatment?

A. It must be worn full-time for 6–8 weeks with no DIP flexion

B. It should be worn only during exercise and activity for at least 4 weeks

C. It should immobilize the entire hand for at least 8 weeks to prevent activiation of wrist and finger flexors

D. It is optional unless pain increases

Quiz Answers

References

Yee, J., & Waseem, M. (2025). Mallet finger injuries. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK459373/

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