Trigger Finger: Causes and Treatment
Trigger finger results from a size mismatch between the flexor tendon and the A1 pulley, creating stenosing tenosynovitis that causes the characteristic catching or locking of the digit. 1
Pathophysiology
The fundamental problem is a discrepancy between the diameter of the flexor tendon and its sheath at the A1 pulley level. 2 This mechanical mismatch leads to inflammation and thickening of the tendon sheath, which progressively worsens the catching phenomenon. 1
Diagnosis
Clinical diagnosis is typically sufficient, though imaging can confirm stenosing tenosynovitis when the diagnosis is uncertain. 3
- Ultrasound is well-suited for evaluating stenosing tenosynovitis due to the superficial location of hand tendons and ability to perform dynamic assessment. 3
- MRI without IV contrast can diagnose stenosing tenosynovitis when advanced imaging is needed, though it is rarely necessary for straightforward cases. 3
Treatment Algorithm
First-Line: Conservative Management
Start with corticosteroid injection into the flexor tendon sheath, which resolves symptoms in approximately 61% of patients after a single injection. 4
- Inject depo-methylprednisolone acetate or triamcinolone acetonide directly into the involved flexor tendon sheath. 4
- Success rates reach nearly 90% when including patients who respond to repeat injections after recurrence. 4
- At 3 months, injectable NSAIDs (diclofenac sodium) show equivalent efficacy to corticosteroids (70% vs 53% complete resolution), though steroids provide faster relief at 3 weeks. 2
Alternative conservative options:
- Activity modification and splinting can be attempted before injection. 5
- Oral NSAIDs or topical NSAID applications may provide symptomatic relief but are less definitive. 2
Important Caveat: Diabetic Patients
Trigger finger in diabetic patients is often less responsive to conservative measures, though the evidence shows no statistically significant difference in injection response rates between diabetic and non-diabetic patients. 2, 1
Second-Line: Surgical Release
If symptoms recur after prolonged pain-free intervals (occurs in 27% of cases), re-injection is effective. 4 However, if injection fails initially or early recurrence occurs (12% of cases), proceed to surgical release. 4
Surgical options include:
- Open A1 pulley release - the standard definitive treatment. 5
- Percutaneous A1 pulley release - minimally invasive alternative. 5
- Excision of a slip of flexor digitorum superficialis - reserved for persistent triggering despite A1 release or persistent flexion contracture. 5
Special Populations
Pediatric trigger thumb: Treat with open A1 pulley release. 5
Pediatric trigger finger: Release A1 pulley, but if triggering persists, excise a slip or all of the flexor digitorum superficialis. 5
Rheumatoid arthritis patients: Require tenosynovectomy instead of A1 pulley release due to different underlying pathology. 1
Complications and Adverse Effects
Corticosteroid injection complications are self-limited and include:
- Pain at injection site, stiffness, ecchymosis, or subcutaneous fat atrophy. 6, 4
- No episodes of postinjection infection or tendon rupture have been reported in prospective studies. 4
Surgical complications are rare but include:
- Bowstringing, digital nerve injury, and continued triggering. 1