From the Research
Trigger finger is a condition characterized by inflammation and narrowing of the tendon sheath in the finger, specifically the A1 pulley, resulting from repetitive microtrauma, leading to fibrocartilaginous metaplasia and a vicious cycle of inflammation and irritation. This pathology occurs when the flexor tendon develops nodular thickening or tenosynovitis, creating a size mismatch between the tendon and its sheath. As a result, the tendon catches or locks when the finger attempts to extend after flexion, causing the characteristic "triggering" or clicking sensation. The pathological process begins with repetitive microtrauma to the tendon, leading to inflammation, collagen deposition, and eventual fibrocartilaginous metaplasia at the tendon-pulley interface, as discussed in a recent review 1.
Some key points to consider in the pathology of trigger finger include:
- The role of repetitive microtrauma in initiating the inflammatory process
- The development of nodular thickening or tenosynovitis in the flexor tendon
- The creation of a size mismatch between the tendon and its sheath, leading to mechanical impingement
- The vicious cycle of inflammation and irritation that perpetuates the condition
- The histological changes in the affected tendon sheath, including fibrous tissue proliferation, hyalinization, and chondroid metaplasia, as well as collagen disorganization and mucoid degeneration in the tendon itself.
The clinical presentation of trigger finger is characterized by pain, stiffness, and the characteristic locking or catching of the affected digit, typically worse in the morning or after periods of inactivity, as noted in a study on the effectiveness of corticosteroid injections for trigger finger 2. Common risk factors for trigger finger include activities requiring repetitive gripping, diabetes mellitus, rheumatoid arthritis, and other inflammatory conditions.
In terms of diagnosis and treatment, trigger finger can be diagnosed through a combination of medical history, physical examination, and functional scales, with ultrasound examination using modern high-frequency probes becoming increasingly important in the comprehensive assessment of patients with trigger finger 1. Treatment options include conservative management with physical therapies, such as external shock wave therapy (ESWT) and ultrasound therapy (UST), as well as surgical interventions, such as percutaneous or open surgery 3. The effectiveness of these treatment options is still being studied, with some evidence suggesting that ESWT and UST may be effective in reducing pain and trigger severity and improving functional level and quality of life 3. However, further research is needed to fully understand the optimal treatment protocol for trigger finger.