Trigger finger

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Causes

By Mayo Clinic staff

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Illustration of trigger finger 
Trigger finger

The cause of trigger finger is a narrowing of the sheath that surrounds the tendon in the affected finger. Tendons are fibrous cords that attach muscle to bone. Each tendon is surrounded by a protective sheath — which in turn is lined with a substance called tenosynovium. The tenosynovium releases lubricating fluid that allows the tendon to glide smoothly within its protective sheath as you bend and straighten your finger — like a cord through a lubricated pipe.

But if the tenosynovium becomes inflamed from repetitive strain injury or overuse or due to inflammatory conditions, such as rheumatoid arthritis, the space within the tendon sheath can become narrow and constricting. The tendon can't glide through the sheath easily, at times catching the finger in a bent position before popping straight. With each catch, the tendon itself becomes irritated and inflamed, worsening the problem. With prolonged inflammation, scarring and thickening (fibrosis) can occur and bumps (nodules) can form.

References
  1. Anderson BC. Trigger finger (stenosing flexor tenosynovitis). http://www.uptodate.com/home/index.html. Accessed Sept. 10, 2009.
  2. Trigger finger. American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org/topic.cfm?topic=A00024&return_link=0. Accessed Sept. 10, 2009.
  3. Akhtar S, et al. Management and referral for trigger finger/thumb. British Medical Journal. 2005;331:30.
  4. Wright PE II. Carpal tunnel, ulnar tunnel, and stenosing tenosynovitis. In: Canale ST, et al. Campbell's Operative Orthopaedics. 11th ed. Philadelphia, Pa.: Mosby Elsevier; 2007. http://www.mdconsult.com/das/book/body/159164477-5/0/1584/566.html?tocnode=55690331&fromURL=566.html#4-u1.0-B978-0-323-03329-9..50076-3--cesec16_4012. Accessed Sept. 10, 2009.
  5. Silver JK. Trigger finger. In: Frontera WR, et al. Essentials of Physical Medicine and Rehabilitation: Musculoskeletal Disorders, Pain, and Rehabilitation. 2nd ed. Philadelphia, Pa.: Saunders Elsevier; 2008. http://www.mdconsult.com/das/book/body/159164477-5/0/1678/36.html?tocnode=55147984&fromURL=36.html. Accessed Sept. 10, 2009.
  6. Peters-Veluthamaningal C, et al. Corticosteroid injection for trigger finger in adults. Cochrane Database of Systematic Reviews. 2009:CD005617.

DS00155

Oct. 16, 2009

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