Trigger finger is a condition in which a finger or the thumb is unable to flex or extend smoothly. It is typically described as a painful snapping or catching sensation during finger extension. The affected digit may remain partially flexed at the proximal interphalangeal (PIP) joint, and attempts to straighten it often result in a sudden release accompanied by an audible or palpable click. Pain may occasionally radiate proximally toward the forearm or even up to the elbow.
The condition results from entrapment of the flexor tendon at the level of the A1 pulley, which becomes thickened—sometimes up to three times its normal size. As the finger extends, the tendon forcibly passes through the narrowed pulley, causing a jerking motion reminiscent of a trigger being released.
In the early stages, symptoms are often more pronounced in the morning and tend to improve throughout the day.
A painful palpable nodule can sometimes be felt at the level of the metacarpophalangeal (MCP) joint. The presence of such a nodule distinguishes the nodular form from the diffuse form of the disease.
Epidemiology
Trigger finger is more commonly observed in females and in patients with underlying conditions such as diabetes mellitus, hypertension, gout, rheumatoid arthritis, carpal tunnel syndrome, De Quervain’s tenosynovitis, and Dupuytren’s disease. It may also occur without any underlying pathology, following local trauma or repetitive, unaccustomed activities.
The thumb is the only digit affected during infancy.
In adults, the ring finger is most frequently involved, followed by the thumb, middle, index, and little fingers, in decreasing order of incidence. This distribution is attributed to anatomical variations. In some cases, multiple digits and even both hands may be affected concurrently.
Treatment
In early stages—particularly in the nodular form—conservative treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), splinting, and local corticosteroid injections is often effective. Response rates to corticosteroid injections range from 50% to 90%, though there are potential adverse effects to consider.
If symptoms persist beyond six months of conservative therapy, surgical intervention is recommended. Intraoperative and postoperative pain control is of particular importance. Additionally, a corticosteroid injection at the end of surgery is often advised to reduce the risk of postoperative tenosynovitis, which may otherwise persist for several months.
In cases of rheumatoid arthritis, preservation of the fibrous pulley is crucial, and only synovectomy should be performed to avoid ulnar drift of the fingers.
Although percutaneous release techniques exist, they are not yet universally accepted as reliably effective.
In cases of congenital trigger thumb, it is generally recommended to observe until the infant reaches one year of age, as spontaneous resolution is common.