What is trigger finger?

Trigger Finger: Definition, Pathophysiology, and Management

Trigger finger is a common hand condition characterized by painful catching or locking of the affected finger during flexion and extension, caused by a size mismatch between the flexor tendon and the first annular (A1) pulley, resulting in stenosing tenosynovitis. This condition significantly impacts hand function and quality of life, with treatment options ranging from conservative management to surgical intervention depending on severity.

Pathophysiology

• Trigger finger occurs when the flexor tendon becomes inflamed and develops nodular thickening, creating a mismatch with the A1 pulley
• This mismatch causes the tendon to catch or "trigger" when passing through the pulley during finger movement
• The A1 pulley is located at the metacarpophalangeal joint (MCP), where the tendons enter the fibrous digital sheath 1
• The condition results in:
  • Pain at the base of the finger or palm
  • Catching or popping sensation during finger movement
  • Locking of the finger in a bent position
  • Morning stiffness of the affected digit

Epidemiology and Risk Factors

• Prevalence of approximately 3% in the general population 2
• Higher prevalence (5-20%) in diabetic patients 2
• More common in women, typically in the fifth to sixth decade of life 3
• Risk factors include:
  • Diabetes mellitus
  • Rheumatoid arthritis
  • Repetitive gripping activities
  • Female gender
  • Middle age

Diagnosis

Diagnosis is primarily clinical, based on:

1. History of clicking, catching, or locking of the affected finger
2. Pain at the base of the digit, often worse in the morning
3. Palpable nodule or tenderness over the A1 pulley
4. Demonstration of triggering with active finger flexion and extension

Imaging is generally not necessary for diagnosis but may be used to exclude other pathologies:

• Ultrasound can identify abnormalities of the flexor tendons and tendon sheaths 4
• MRI may be helpful in atypical presentations to evaluate tendon injuries 4

Treatment Algorithm

1. Conservative Management (First-line)

• Activity modification to reduce repetitive gripping
• Splinting of the affected digit in extension, particularly at night
• NSAIDs for pain and inflammation
• Corticosteroid injections:
  • Highly effective with resolution in 61% of cases after a single injection 5
  • Can be repeated if symptoms recur after initial improvement
  • Nearly 90% success rate with one or more injections 5
  • Potential side effects include pain at injection site, subcutaneous fat atrophy, and skin depigmentation

2. Surgical Management (For refractory cases)

Indicated when:

• Failed response to conservative measures (including 1-2 corticosteroid injections)
• Recurrent symptoms after initial improvement
• Fixed flexion contracture

Surgical options include:

• Open A1 pulley release (standard approach)
• Percutaneous A1 pulley release
• In persistent cases, excision of a slip of the flexor digitorum superficialis may be required 6

Special Populations

1. Diabetic Patients

   • Less responsive to conservative measures 1
   • May require earlier surgical intervention

2. Rheumatoid Arthritis Patients

   • Require tenosynovectomy rather than simple A1 pulley release 1

3. Pediatric Patients

   • Trigger thumb resolves reliably with A1 pulley release
   • Other digits may require more extensive surgery 1, 6

Complications

Complications are rare but may include:

• Bowstringing of the flexor tendon
• Digital nerve injury
• Continued triggering despite treatment
• Infection (rare with proper technique)
• Tendon rupture (extremely rare)

Prognosis

With appropriate treatment, the prognosis for trigger finger is excellent:

• Conservative treatment is successful in approximately 90% of cases 5
• Surgical release has a success rate of over 95%
• Recurrence is possible but uncommon after successful treatment

Early diagnosis and treatment are important to prevent permanent contracture of the affected digit and to restore normal hand function and quality of life.