Causes of Trigger Finger
Trigger finger is fundamentally a mechanical problem caused by a size mismatch between the flexor tendon and the A1 pulley, leading to inflammation and narrowing that prevents smooth tendon gliding. 1
Primary Pathophysiology
The core mechanism involves stenosing flexor tenosynovitis where the flexor tendon becomes too large to glide smoothly through the A1 pulley, creating the characteristic catching, clicking, and locking symptoms. 2, 1 While inflammation and pulley alteration are identified as triggering factors, the true etiology remains incompletely understood in the literature. 3
Key Risk Factors and Associations
Demographic Factors
- Female sex is a major risk factor, with trigger finger occurring much more commonly in middle-aged women than men, typically in the fifth to sixth decade of life. 4, 2
- Age over 40 years represents the typical age of onset, though it can afflict anyone. 4, 2
Medical Comorbidities
- Diabetes mellitus is strongly associated with trigger finger and makes the condition less responsive to conservative treatment measures. 4, 1
- Carpal tunnel syndrome frequently coexists with trigger finger. 4
- Rheumatoid arthritis patients develop trigger finger through a different mechanism involving tenosynovitis rather than simple A1 pulley stenosis. 1
Mechanical and Occupational Factors
- Repetitive finger movements and repetitive occupational hand tasks contribute to development, though the exact dose-response relationship varies by specific task patterns. 4, 3
- The thumb is the most commonly affected digit, followed by other fingers depending on usage patterns. 4
Important Clinical Distinctions
The condition represents a degenerative tendinopathy (tendinosis) rather than purely inflammatory tenosynovitis, despite the traditional nomenclature. 1 This distinction matters because it explains why anti-inflammatory treatments alone may not fully resolve the mechanical obstruction.
In pediatric trigger thumb, the pathophysiology differs from adults and typically requires different surgical considerations, including potential excision of flexor digitorum superficialis slips if A1 release alone is insufficient. 5
Common Pitfalls
Do not confuse trigger finger with other hand conditions that may present similarly—fractures, tumors, or other traumatic soft tissue injuries must be excluded through careful clinical examination. 2 In diabetic patients, expect reduced response to conservative measures and plan treatment accordingly. 1