What is Trigger Finger?
Trigger finger, also known as stenosing tenosynovitis or stenosing flexor tenosynovitis, is a condition where inflammation and thickening of the tendon sheath causes the flexor tendon to catch or lock as it passes through the A1 pulley, resulting in painful clicking, catching, or locking of the affected finger during movement. 1, 2
Underlying Pathophysiology
The core problem is a size mismatch between the flexor tendon and the first annular (A1) pulley that creates a mechanical obstruction 2. This occurs when:
- The synovial sheath surrounding the flexor tendon becomes inflamed and thickened 1
- The A1 pulley (a fibrous tunnel through which the tendon glides) becomes constricted 3
- The tendon cannot smoothly pass through the narrowed osseofibrous tunnel, causing it to catch or lock 3
Clinical Presentation
Patients typically experience:
- Painful clicking or snapping when attempting to bend or straighten the affected finger 1
- Locking of the finger in a bent position, requiring passive straightening with the other hand 4
- Morning stiffness that may improve throughout the day 4
- Palpable nodule at the base of the affected finger, typically at the level of the metacarpophalangeal joint 2
- Functional deficit of the hand that interferes with daily activities 1
High-Risk Populations
Certain groups are particularly susceptible to developing trigger finger:
- Middle-aged women are affected more frequently than men 4
- Diabetic patients often show less response to conservative treatments 2
- Patients with rheumatoid arthritis may develop secondary stenosing tenosynovitis 2, 4
- Individuals with gout or other connective tissue disorders 4
Critical Caveat for Rheumatoid Arthritis
In patients with rheumatoid arthritis, the underlying pathology differs—these patients require tenosynovectomy rather than simple A1 pulley release because the problem is proliferative synovitis rather than mechanical constriction alone 2.
Diagnostic Approach
The diagnosis is primarily clinical and can be made through adequate physical examination without requiring imaging in most cases 4. However, modern diagnostic tools include:
- Ultrasound examination using high-frequency probes can visualize the thickened A1 pulley constricting the tendon and confirm the diagnosis 1, 3
- MRI or ultrasound can diagnose stenosing tenosynovitis when imaging is needed to differentiate from other tendon pathologies 5
Pediatric Considerations
Trigger finger in children represents a distinct entity from the adult form: