The extensor mechanism of the finger is most vulnerable to rupture at which zone following closed trauma to the distal phalanx?

• A Zone V (dorsum of hand over metacarpal)
• B Zone I (distal to DIP joint — terminal tendon) ✓
• C Zone III (proximal interphalangeal joint — central slip)
• D Zone VI (over the wrist extensor retinaculum)

Explanation

Zone I (distal to the DIP joint) injury of the terminal extensor tendon produces a mallet finger deformity — an extensor lag at the DIP joint due to avulsion or rupture of the terminal extensor tendon. It is the most common closed tendon injury of the hand. Treatment is continuous DIP joint splinting in full extension for 6–8 weeks. Central slip (Zone III) rupture causes boutonnière deformity.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.