Extensor Tendon Laceration Finger 6 smInjuries to the hand are fraught with multiple, concurrent injuries. Many injuries may have chronic debilitating complications, if not detected early. One such example is a finger laceration with a concurrent extensor tendon injury, causing delayed boutonniere deformity formation and limited function. Review the anatomy of the extensor tendon. View the video on how to perform the Elson’s test to detect a central slip tendon injury.

Finger anatomy

The extensor tendon complex of each finger consists of a central band (or central slip) and paired lateral bands.

  • Central band: Portion of the extensor tendon which inserts on the dorsal aspect of the middle phalanx
  • Lateral bands: Extends from the interosseous muscles and inserts at the base of the distal phalanx

CentralSlipExtensorTendon sm


The upper diagram shows normal anatomy, and the lower diagram shows a central slip tendon laceration (denoted by blue asterisk).

A ruptured central slip tendon injury will cause the lateral bands to slide volarly and cause abnormal flexion of the PIP joint and extension of the DIP joint.

Elson’s test

The Elson’s test essentially isolates the central band/slip of the extensor tendon complex [1]. [original Elson test PDF]

  1. Position the patient’s PIP in 90-degrees flexion. This normally keeps the central band taut and the lateral bands loose.
  2. Ask the patient to extend the PIP, while the provider’s finger applies counterforce at the middle phalanx.
  3. NORMAL Elson’s test: Results in active extension of the PIP joint and a floppy DIP.
  4. ABNORMAL Elson’s test: Results in no active extension of the PIP joint and a slightly extended, taut DIP.



  1. Rubin J, Bozentka DJ, Bora FW. Diagnosis of closed central slip injuries. A cadaveric analysis of non-invasive tests. J Hand Surg Br. 1996 Oct;21(5):614-6. Pubmed
Michelle Lin, MD
ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg SF General. ALiEM Founder @aliemteam #PostitPearls at https://t.co/50EapJORCa Bio: https://t.co/7v7cgJqNEn
Michelle Lin, MD