Trigger Finger: A Complication of RA and Diabetes
What is trigger finger?
Trigger finger (also called stenosing tenosynovitis or stenosing tendovaginitis) is a painful condition in which a finger or thumb becomes "locked" in place after it has been flexed. There may be clicking, popping, or a catching sensation in the affected finger, which becomes difficult to straighten without assistance. Some patients may experience stiffness and reduced motion without the characteristic catching or locking.
Stenosing tendovaginitis (i.e., narrowing inflammation of the tendon sheath) can affect any of 23 extrinsic tendons that power the wrist and hand. However, trigger finger most commonly affects the little finger, ring finger, or thumb. Additional symptoms include a bump or lump (nodule) at the base of a finger near the palm, tenderness, or lingering soreness at the base of a finger or thumb.
What causes trigger finger?
Trigger finger is caused by inflammation and/or hypertrophy (enlargement) of the tendon sheath. This inflammation narrows the space in the tendon sheath, which acts like a tunnel through which the tendon glides, and progressively restricts the motion of the flexor tendon passing through the wrist or hand.
A tendon is the strong tissue that attaches muscle to bone and helps us move parts of our body. When a muscle in the forearm contracts and pulls on the tendon attached to a finger, it causes that finger to bend (flex). A tendon which travels through a narrowed sheath may be able to move in one direction but be unable to slide back into its original, neutral position. This causes the finger to remain in a flexed position.
Who gets trigger finger?
Although anyone can develop trigger finger, it occurs more frequently in women than men (4:1 ratio), especially in women over the age of 40, and in people diagnosed with diabetes, rheumatoid arthritis, hypothyroidism, amyloidosis, or carpal tunnel syndrome. More than 65% of patients with rheumatoid arthritis will develop some form of tenosynovitis of the hand or wrist (Skirven, 2011).
Research shows increased risk of developing problems with tendons in the hand and wrist in people who perform highly repetitive and forceful jobs. For example, musicians, such as piano players and guitarists, exert significant stress on multiple tendons in the wrist and fingers. They are prone to developing tendonitis, especially if they dramatically increase their practice time (Amadio, 1990), and are at risk for developing trigger finger.
How is trigger finger diagnosed?
The classic presentation of popping and locking of a trigger finger may be all that is needed for diagnosis. Over time, a painful nodule may develop at the base of the affected finger as a result of swelling. However, acute onset of symptoms may also present with pain and swelling over the involved flexor sheath with avoidance of finger motion, in which case traumatic injury or infection must be excluded as possible causes.
Other causes of a locking finger include dislocation, Dupuytren's contracture, focal dystonia, flexor tendon/sheath tumor, sesamoid bone anomalies, post-traumatic tendon entrapment on the metacarpal head, and even hysteria (Makkouk, 2008). Other causes of pain at the MCP joint include de Quervain's tenosynovitis, ulnar collateral ligament injury of the thumb (gamekeeper's thumb), MCP joint sprain, extensor apparatus injury, and MCP osteoarthritis.
How is trigger finger treated?
Initial conservative treatment of trigger finger involves resting the hand and taking a break from repetitive activities for 4-6 weeks, non-steroidal anti-inflammatory drugs for pain control, applying heat or ice to reduce swelling, wearing a splint and MCP joint immobilization, corticosteroid injection, and gently stretching the fingers to increase range of motion.
Wearing a plastic splint attached to your finger (or thumb) so that it remains straight helps to prevent the friction caused by flexor tendon movement through the sheath until inflammation resolves. It is less effective for those with severe triggering or long-term symptoms. Splinting at night may be helpful for those who are most bothered by symptoms in the morning.
Corticosteroid injections are generally successful in relieving the symptoms of trigger finger. A steroid injection is given into the tendon sheath to reduce inflammation and relieve friction in the tendon sheath. Often, the steroid is combined with a local anesthetic to reduce the pain of the injection.
If steroid injections do not work, surgery (either open or percutaneous) can be done to widen the tendon sheath. Surgery is highly successful and widely regarded as the ultimate treatment for trigger finger after other treatment have failed. Surgery does carry a small risk of nerve damage that causes numbness in the finger, as well as risk of infection.
How can I prevent recurrence of trigger finger?
After symptoms have resolved and tissue has healed, there are a few things you can try to prevent recurrence of trigger finger. Consulting a hand therapist will help you know which interventions are most appropriate for you.
Massage may improve tendon function by increasing circulation and reducing increased thickness of tendons at pulley points. Anecdotal reports indicate that transverse friction massage (TFM) - in which the clinician moves the patient's skin over the affected area perpendicular to the length of tendon fiber with increasing pressure and working up to 15 minutes - may improve symptoms.
Gliding and stretching the affected tendons can prevent or reduce adhesions in the tendon sheath and increase range of motion. Tendons should be moved gently, progressively, and in pain-free ranges. Tendon gliding can be used to glide both flexor and extensor tendons of the fingers. Strain during joint movement can be decreased by stretching the appropriate muscle-tendon unit. (I teach each of my piano students how to properly stretch the forearm muscles and tendons which reach to each of the fingers to prevent injury.)
Strengthening exercises may be initiated when acute symptoms have subsided. It is best to consult with a hand therapist to determine which exercises are recommended for you, as there are many types of isometric, isotonic, and isokinetic exercises which need to be done without causing additional stress or injury. Using putty, free weights, and a resistance band may be recommended for home use.
Lifestyle modifications, such as using ergonomic tools to alter technique, may help prevent recurrence. Making ergonomic adjustments or using gloves to distribute pressure reduces the force necessary to accomplish tasks. Keeping the forearm and wrist in a neutral position helps to optimize muscle efficiency and takes stress off of the tendons as they travel over the wrist.
Additional strategies one should use to reduce the force necessary to grip or pinch objects include the following: use friction material on hand tools and utensils; maximize surface contact with the hand; wear handle straps to relax grip intermittently; use electrically powered tools to replace manual tools; apply force at the middle of the finger rather than the tip to reduce torque at the base of the finger where many trigger finger problems originate.
Amadio PC, Russotti GM. Evaluation and treatment of hand and wrist disorders in musicians. Hand Clin. 1990;6:405.
Griffiths DL. Tenosynovitis and Tendovaginitis. Br Med J. 1952 Mar;1(4759):645-7.
Makkouk AH, Oetgen ME, Swigart CR, Dodds SD. Trigger finger: etiology, evaluation, and treatment. Curr Rev Musculoskelet Med. 2008 Jun;1:92-96. doi 10.1007/s12178-007-9012-1
Skirven TM, Osterman AL, Fedorczyk JM, Amadio PC. Management of Hand and Wrist Tendinopathies. In: Rehabilitation of the Hand and Upper Extremity, 6th edition. St. Louis, MO: Elsevier Mosby, 2011.