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)