Trigger Finger Definition
Trigger finger, also known as stenosing flexor tenosynovitis, is a common tendinopathy characterized by entrapment of the flexor tendon at the A1 pulley, resulting from a size mismatch between the flexor tendon and the first annular (A1) pulley. 1, 2
Pathophysiology
- The underlying mechanism involves a size discrepancy between the flexor tendon and the A1 pulley through which it glides, leading to mechanical catching and locking of the affected digit. 2
- The pathology represents degenerative tendinopathy (tendinosis) rather than acute inflammation, despite the historical term "tenosynovitis." 3
- Repetitive loading causes degenerative changes in the normally well-organized collagen fiber structure of the flexor tendons. 3
Clinical Presentation
- Patients experience catching, clicking, or locking of the affected finger during flexion and extension movements. 1
- The condition causes functional deficit of the hand that can significantly impact daily activities. 4
- Pain and tenderness are typically localized over the A1 pulley at the base of the affected finger. 1
- In advanced cases, the finger may become locked in flexion and require passive manipulation to extend. 2
Diagnostic Approach
- Clinical assessment is usually adequate for diagnosis, with imaging reserved for uncertain cases. 5
- When imaging is needed, ultrasound is the preferred modality because the flexor tendons are superficially located and the technique allows dynamic real-time assessment during finger movement. 5
- MRI can accurately diagnose stenosing tenosynovitis when advanced imaging is required, though it is seldom necessary for uncomplicated cases. 5
Common Pitfalls
- Avoid labeling chronic cases as "tendinitis" when they represent degenerative tendinopathy, as this distinction affects treatment planning. 3
- The condition differs from infectious tenosynovitis (such as nontuberculous mycobacterial tenosynovitis following trauma), which requires entirely different management. 6