Trigger finger, or stenosing tenosynovitis, is a condition causing discomfort and limited finger movement. It primarily manifests as a catching or locking sensation when a finger or thumb is bent and straightened.
Understanding Trigger Finger
Trigger finger develops when the smooth gliding mechanism of a finger tendon is disrupted. Tendons are cord-like structures connecting muscles to bones, enabling movement. Each flexor tendon moves through a protective tunnel called a tendon sheath, which contains tissue bands called pulleys. The A1 pulley, located at the base of the finger where it meets the palm, is most frequently involved.
The flexor tendon or its sheath becomes inflamed and thickens. This thickening, sometimes with a small nodule, prevents the tendon from smoothly sliding through the A1 pulley. The resulting friction causes symptoms like clicking, popping, or a catching sensation, often requiring force to straighten the finger. Tenderness at the base of the affected finger and stiffness are also common.
Common Factors Contributing to Trigger Finger
Several non-genetic factors and medical conditions can increase the likelihood of developing trigger finger. Occupations or hobbies involving repetitive gripping, extensive hand use, or prolonged grasping actions pose a higher risk. Examples include farming, gardening, industrial work, using tools, or playing certain sports, as these activities can irritate and inflame the tendon and its sheath.
Underlying health conditions also contribute. Diabetes mellitus is a significant risk factor, as high blood sugar levels can lead to tendon thickening. Rheumatoid arthritis, an autoimmune disease causing joint inflammation, can also affect the tendon sheath, leading to inflammation and thickening that impedes tendon movement. Gout, hypothyroidism, and carpal tunnel syndrome surgery can also increase risk.
The Role of Genetics
While not typically a directly inherited genetic disorder, evidence suggests a genetic predisposition can play a role in trigger finger’s development. It involves a complex interplay of genetic tendencies and other contributing factors. Recent genome-wide association studies (GWAS) have identified specific genetic variants associated with increased risk, such as loci on chromosome 13 (KLHL1 gene) and chromosome 14 (POLE2 gene).
These studies also found a shared genetic variant increasing the risk for both trigger finger and carpal tunnel syndrome. This variant is associated with increased signaling through the Insulin-like Growth Factor 1 (IGF-1) pathway, a growth hormone pathway. This pathway’s increased signaling also correlates with diabetes onset, a known trigger finger risk factor. This suggests a genetic tendency towards predisposing conditions or tissue responses can influence its occurrence within families.
Getting Help for Trigger Finger
Diagnosis primarily relies on a physical examination. A healthcare professional will assess the hand for tenderness at the base of the affected finger, check for a palpable nodule, and observe finger movement for clicking, catching, or locking sensations. Imaging tests like X-rays are generally not necessary.
Treatment approaches vary depending on symptom severity. Conservative options are often the first line of defense, including resting the hand, avoiding aggravating activities, and wearing a splint to reduce tendon irritation. Nonsteroidal anti-inflammatory drugs (NSAIDs) can help manage pain and inflammation.
Corticosteroid injections into the tendon sheath are a common and effective treatment, reducing inflammation and allowing the tendon to glide more freely. If conservative measures do not provide relief, surgical intervention may be considered. Procedures like percutaneous release or open surgery aim to widen the A1 pulley, allowing the tendon to move without obstruction. Consulting a healthcare professional is important for proper diagnosis and to determine the most suitable treatment plan.