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Trigger finger

Incidence
Trigger fingers are very common in adults, particularly in middle aged women and diabetics.

Other predisposing factors can include
  • Collagen disorders
  • Secondary to sharp trauma (partial laceration of flexor tendon)
  • Rheumatoid Arthritis (causes tenosynovitis- inflammation of the tendon)
  • Gout

Pathology
Thickening of the fibrous tendon sheath occurs with chronic inflammation
    • often following minor trauma or unaccustomed activity
  • The flexor tendons become trapped at the entrance to the sheath
  • On forced extension it passes the constriction with a snap

Presentation
  • Any finger can lock or snap but most often it is the ring and middle
  • Finger locks with flexion, remains flexed when trying to straighten, then snaps into extension
  • Tender nodule over the A1 pulley which is the entrance to the tendon sheath(just proximal to the distal palmar crease)
  • Many people complain of pain at the proximal interphalangeal joint of the finger

Treatment
  • Steroid injection at  the entrance to tendon sheath
    • Can be curative if early presentation and symptoms mild 
  • Surgical release
    • Usually performed under local anaesthetic and sedation
    • Small incision just distal to the distal palmar crease
    • A1 pulley/ tendon sheath is longitudinally incised until triggering is relieved
    • Explore tendon sheath, remove nodules and complete tenosynovectomy
  • In rheumatoid arthritis the pulley is preserved (synovectomy performed through an extensile approach)

Recovery
  • The triggering/ locking is relieved immediately but soreness often persists (from tendon inflammation) for 4- 6 weeks
  • Improvement continues for about 3 months

Nb. Trigger fingers in kids are less common but more complicated
  • Usually are not fixed in flexion
  • Role of non-operative treatment is unclear
  • There may be abnormal tendon anatomy, nodular formation within tendon and/ or tightness of A2 or A3 pulleys
  • Potential for extensile approach in case release of A1 pulley does not relieve triggering