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 frequently or for long periods, 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 more irritated and inflamed, worsening the problem. With prolonged inflammation, scarring and thickening (fibrosis) can occur and bumps (nodules) can form.
Oct. 25, 2011
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- 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. 14, 2011.
- 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. 7, 2011.
- Peters-Veluthamaningal C, et al. Corticosteroid injection for trigger finger in adults. Cochrane Database of Systematic Reviews. 2009:CD005617. http://www2.cochrane.org/reviews. Accessed Sept. 14, 2011.
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