What is Trigger Finger
Trigger finger, also known as stenosing flexor tenosynovitis, is a common hand condition caused by a size mismatch between the flexor tendon and the first annular (A1) pulley, resulting in painful catching or locking of the affected finger during flexion and extension movements. 1, 2, 3
Pathophysiology
- The condition occurs when the flexor tendon becomes too large to glide smoothly through the A1 pulley at the base of the finger, creating mechanical obstruction 3
- This size discrepancy leads to inflammation of the synovial sheath surrounding the flexor tendon, perpetuating the problem 1, 4
- The thickened retinaculum or pulley constricts the osseofibrous tunnel through which the tendon runs, which is the cardinal pathologic finding 4
Clinical Presentation
- Patients experience painful catching, clicking, or locking of the affected finger, particularly during flexion movements 1, 2
- The finger may become stuck in a flexed position and require passive extension 2, 5
- In long-standing cases, proximal interphalangeal joint contracture may develop 5
- Symptoms typically cause functional deficit of the hand, limiting daily activities 1
Risk Factors and Associated Conditions
- Diabetes mellitus is strongly associated with trigger finger, making it particularly common in this population 5, 3
- Rheumatoid arthritis increases risk, though these patients require different surgical management (tenosynovectomy rather than simple A1 pulley release) 5, 3
- The condition can affect both adults and children, though pediatric cases (especially trigger thumb) have distinct treatment considerations 2, 3
Diagnostic Approach
- Diagnosis is primarily clinical, based on history and physical examination findings of catching or locking during finger flexion 1, 2
- Ultrasound examination using high-frequency probes has become part of comprehensive assessment, showing thickened hypoechoic tenosynovial sheath and the constricted A1 pulley 1, 4
- MRI without IV contrast can diagnose stenosing tenosynovitis when comprehensive soft tissue evaluation is needed 6
Important Clinical Caveats
- In diabetic patients, trigger finger is often less responsive to conservative measures, requiring earlier consideration of surgical intervention 3
- Multiple fingers can be affected simultaneously 2, 5
- The condition represents stenosing flexor tenosynovitis specifically, distinguishing it from other forms of tenosynovitis affecting extensor tendons 4