Mallet Finger: Diagnosis, Splinting, and Surgical Indications

🧠 What is Mallet Finger?

Mallet finger, also known as baseball finger, is the disruption of the terminal extensor tendon at the distal interphalangeal (DIP) joint, causing the fingertip to droop and preventing active extension.

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🦴 Pathophysiology

• Mechanism: Sudden forced flexion of an extended DIP joint (e.g., catching a ball)

• Injury site:

  • Tendinous rupture of the extensor digitorum tendon

  • Or bony avulsion fracture at the dorsal base of distal phalanx
    

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👀 Clinical Presentation

🖐 Symptoms:

• Sudden inability to extend DIP joint

• Fingertip droops at rest

• Localized pain, swelling, tenderness over dorsal DIP
  

👨‍⚕️ Physical Exam:

• Passive extension is possible, but no active extension

• Tenderness over dorsal DIP joint

• No rotational deformity
  

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🧪 Investigations

• X-ray of the affected finger (lateral + AP view):

  • Look for avulsion fracture at the distal phalanx

  • Assess for joint subluxation
    

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🩺 Management Plan

🟢 Non-Operative (First-line in most cases)

Indications:

• Tendon rupture or small avulsion fracture

• No joint subluxation

🔹 Splinting:

• Continuous extension splinting of the DIP joint

• PIP joint must remain free

• Splint types: stack splint, aluminum foam, or custom thermoplastic

⏱ Duration:

• 6–8 weeks 24/7

• Additional 2–4 weeks night splinting

• Patient must avoid any DIP flexion, or clock restarts
  

🔴 Surgical Indications

• Large bony avulsion (>30–50% of joint)

• DIP joint subluxation

• Failed conservative therapy

• Chronic mallet with swan-neck deformity

Surgical Options:

• ORIF (open reduction internal fixation)

• K-wire fixation

• Tendon repair with anchor
  

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📚 Prognosis

• Excellent recovery with compliant splinting

• Delay in treatment ➜ permanent extensor lag

• Chronic untreated ➜ swan-neck deformity
  

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🔑 Clinical Pearls

• Always X-ray before splinting to avoid missing a fracture

• Educate patient: one flexion resets 6-week healing

• Compare with mallet thumb—treatment differs in splint design and joint involved
  

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✅ Key Summary for OSCE/USMLE

Item	Details
Affected Joint	DIP of fingers (not thumb)
Cause	Forced flexion of extended DIP
Diagnosis	Clinical + lateral finger X-ray
First-line Treatment	DIP extension splint for 6–8 weeks
Surgical Indication	Subluxation, large avulsion, failure of splinting