Trigger Digits

Order of Incidence

  • Ring > Thumb > Middle > Index > Little

Classification

  • Nodular or Diffuse
  • Nodular type responds better to injections than diffuse type

Pathological Process

Adults:

  • The flexor tendons enter the pulley system at an acute angle
  • Causes friction at the A1 pulley
  • Results in thickening of tendon sheath and inflammation → tenosynovitis
  • A nodule from tendon fraying forms just distal to the pulley or
  • Diffuse inflammation of the sheath occurs distal to A1
  • The pulley secondarily thickens in response, exacerbating the problem
    • Undergoes fibrocartilaginous metaplasia
  • In the thumb, the FPL enters at an acute angle to put it at a mechanical advantage, but this predisposes to triggering

Children:

  • Primarily affects the thumb
  • Associated with nodule formation but not A1 pulley thickening
  • Don’t respond well to non-operative treatment as they are usually longstanding

Associations

  • Females
  • Dupuytren’s contracture
  • Diabetes
  • De Quervain’s tenosynovitis
  • Rheumatoid arthritis
  • Gout
  • Hypertension

Diagnosis

  • Pain, catching, locking of the finger
  • Worse in morning if nodular type

Treatment

Determining Factors:

  1. Is it nodular or diffuse?
  2. What is the duration of symptoms?
  3. Is there an underlying treatable pathology?
  4. Duration over 6 months decreases likelihood of non-operative treatment success
  5. Diffuse disease decreases likelihood of non-operative treatment success
  6. But – even in these situations, injection will cure half

Non-Operative Treatment

  • NSAIDs, ice, activity modification
  • Splinting (MCPJ only)
  • Steroid Injection:
    • Effective in up to 90% with nodular type (with up to 3 injections)
    • Complications:
      • Damage to NV bundle
      • Intratendinous injection
      • Skin pigmentation changes
      • Recurrence
      • Transient hyperglycemia

Operative Treatment

  • Open procedure under local anesthesia with tourniquet
  • Incision Types:
    • Oblique, transverse, or longitudinal incision
  • Landmarks:
    • Proximal phalanx crease distance for A1 pulley landmark over MCPJ
    • Thumb: Skin crease at the base of the thumb (beware of radial digital nerve)
    • Release thumb A1 on radial aspect – away from oblique pulley
  • If diffuse, a more extensive release and debridement of inflamed synovium
  • Utmost care when approaching A2 pulley (can be windowed in worst cases)

Complications:

  • NV damage (especially in thumb)
  • A2 pulley release
  • Recurrence (rare)
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