TRIGGER FINGER/ THUMB

TRIGGER FINGER/ THUMB


TRIGGER FINGER/THUMB

  • A Trigger Finger is described as the catching or locking of a finger in a bent (flexed) position.
  • Stenosing tenosynovitis, more commonly known as “trigger finger” or “trigger thumb”.
  • Affecting the tendons that bend the fingers.
  • Caused by inflammation that prevents the tendon from gliding smoothly.  

Mechanism:
  • Tendons that bend the fingers pass through a series of loops, called “pulleys”.
  • If the tendon swells, or if the pulleys tighten, the tendon can get caught which limits smooth motion of the finger.

The pulleys are of two types:

  1. Annular A – These are composed of single fibrous bands. Thus these are ring-like structures
  2. Cruciate C – Cruciate pulleys consist of crossing fibrous bands.
  • A1 – over metacarpophalangeal joints. It is the pulley where triggering phenomenon occurs.
  • A2 – over proximal end of the proximal phalanx
  • C1 – over the middle of the proximal phalanx
  • A3 – over the proximal interphalangeal (PIP) joint
  • C2 – over the proximal end of the middle phalanx
  • A4 – over the middle of the middle phalanx
  • C3 – over the distal end of the middle phalanx
  • A5 – over the proximal end of the distal phalanx

 

Epidemiology:

  • more common in diabetics
  • More common in women
  • ring finger most commonly involved
Associated conditions:

  • diabetes mellitus
  • rheumatoid arthritis
  • amyloidosis

Symptoms:

    • finger clicking
    • pain at distal palm near A1 pulley
    • finger becoming “locked in flexed position
  • Physical exam
    • tenderness to palpation over A1 pulley 
    • a palpable bump may be present near the same location
Treatment:

Nonoperative

night splinting, activity modification, NSAIDS

  • indications
  • first line of treatment

steroid injections 

  • indications
  • best initial treatment for fingers, not for thumb
  • technique
  • give 1 to 3 injections in flexor tendon sheath
  • diabetics do not respond as well as non-diabetics

Operative

surgical debridement and release of the A-1 pulley

  • indications
  • in cases that fail nonoperative treatment

release of A1 pulley and 1 slip of FDS (usually ulnar slip) 

  • indications
  • pediatric trigger finger
  • presents with Notta’s nodule (proximal to A1 pulley), flexion contracture and triggering
  • may need to release remaining FDS slip and A3 pulley as well

Exam Important

  • Stenosing tenosynovitis of the flexor tendon sheath is also known as Trigger finger.
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