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, clicking, or locking of the affected finger during flexion and extension movements. 1, 2, 3
Pathophysiology
- The condition occurs when inflammation and thickening of the tendon sheath creates a mechanical obstruction at the A1 pulley level, preventing smooth gliding of the flexor tendon 4, 3
- The thickened retinaculum or pulley constricts the osseofibrous tunnel through which the tendon runs, causing the characteristic triggering phenomenon 4
- This represents a stenosing flexor tenosynovitis affecting the flexor digitorum tendons of the fingers 1, 2
Clinical Presentation
- Patients experience painful catching, clicking, or frank locking of the digit during flexion and extension movements 2, 3
- The finger may become stuck in a flexed position and require passive manipulation to extend 2
- Pain is typically localized to the palm at the base of the affected finger, corresponding to the A1 pulley location 3
- In long-standing cases, proximal interphalangeal joint contracture may develop 5
Risk Factors and Associated Conditions
- Diabetes mellitus is strongly associated with trigger finger, and diabetic patients often respond less favorably to conservative treatments 5, 3
- Rheumatoid arthritis patients may develop trigger finger, though the underlying pathology differs (requiring tenosynovectomy rather than simple A1 pulley release) 5, 3
- The condition is more common in adults but can occur in pediatric populations, particularly trigger thumb in children 2
Diagnostic Approach
- Diagnosis is primarily clinical, based on history and physical examination demonstrating the characteristic triggering phenomenon 1, 2
- Ultrasound examination using high-frequency probes has become part of comprehensive assessment, showing thickened tendon sheath and A1 pulley 1, 4
- The cardinal ultrasound finding is a thickened retinaculum or pulley constricting the osseofibrous tunnel 4
- Functional scales and physical examination findings guide treatment planning 1
Distinction from Other Conditions
- Trigger finger specifically involves the flexor tendons and A1 pulley, distinguishing it from other forms of stenosing tenosynovitis such as de Quervain tenosynovitis (affecting the first dorsal compartment) or intersection syndrome 4, 5
- Unlike generalized tenosynovitis associated with inflammatory arthritis, trigger finger represents a localized mechanical problem at the A1 pulley 4, 3