Last July, I did this post on trigger finger (or stenosing tenosynovitis).
Stenosing tenosynovitis is more commonly known as trigger finger or trigger thumb. It involves the pulleys and tendons in the hand. These tendons and pulley work together to bend the fingers. The tendons work like long ropes going from the muscles in the forearm to connect to the bones of the fingers and thumb. In the finger, the pulleys are a series of rings (made of connective tissue) that form a tunnel that the tendons must pass through. This is very much like the guides on a fishing rod through which the line (or tendon) passes. These pulleys hold the tendons close against the bone. The tendons and the pulley (tunnel) have a slick lining that allows easy gliding. Photo credit--ASSH.
When the tendon develops a nodule or swelling of its lining, it has difficulty passing through the pulley (which is not elastic, but fixed in diameter). The "popping" or "catching" feeling in the finger or thumb comes from the tendon "squeezing" through and giving as it makes it past the pulley. The swollen tendon is irritated more as it has to be squeezed through the pulley, producing more swelling. A vicious cycle of triggering, inflammation, and swelling. Sometimes the finger will become stuck (locked) and it may be hard to straighten or bend the finger. This is like having a finger swell and not being able to get your ring off.
So what causes this condition. Repetitive grasping of objects or an injury to the palm may irritate the flexor tendons. Medical conditions such as rheumatoid arthritis, gout, and diabetes may create swelling around the tendons which then lead to the "vicious" cycle of irritation/inflammation/swelling. Sometimes the cause is not clear.
The goal of treatment is to eliminate the catching or locking and allow movement without discomfort. To do this the swelling around the tendon must be reduced to allow smooth gliding of the tendon. Wearing a splint or taking anti-inflammatory medication by mouth or injection into the area around the tendon (a corticosteroid shot) are ways to reduce the swelling. Changing how the hand is used, better body mechanics to reduce the impact or repetitive motions helps. If nonsurgical forms of treatment do not improve symptoms, then surgery may be recommended. This surgery is usually performed on an outpatient basis. Most often it is done using local anesthesia, but a regional (where only the arm is numbed) or a general may be used. The surgery cuts the pulley (only one and the finger still has other pulleys to keep it near the bone) which gives the tendon more room to glide, removing the restriction (cutting the ring off the swollen finger). Active motion of the finger is generally begun immediately after surgery. Normal use of the hand can be resumed once comfort permits.
Recently, there was an article in the Journal of Bone and Joint Surgery on prognostic indicators that can be used to "predict" the recurrence of triggering after corticosteriod injection. (photo credit) See the reference below.
In the study, there were 124 trigger digits in 119 patients. Of these 70 digits (56%) had a recurrence of symptoms at a median of 5.6 months after the injection. Twenty-two digits (18%) underwent surgical release at a median of 7.4 months after the injection.
According to the Kaplan-Meier analysis, the estimated rate of freedom from symptom recurrence was 70% (95% confidence interval, 63% to 77%) at six months and 45% (95% confidence interval, 36% to 54%) at twelve months and the estimated rate of freedom from surgical release was 95% (95% confidence interval, 92% to 98%) at six months and 83% (95% confidence interval, 77% to 89%) at twelve months.
Insulin-dependent diabetes mellitus was identified as a strong predictor of symptom recurrence (p < 0.01). Younger age (p < 0.01), involvement of other digits prior to presentation (p < 0.01), and a history of other tendinopathies of the upper extremity (p = 0.02) were all independent predictors of a surgical release. The duration and severity of symptoms were not predictive of poor outcomes following injections.
Trigger Finger: Prognostic Indicators of Recurrence Following Corticosteroid Injection; The Journal of Bone and Joint Surgery (American). 2008;90:1665-1672; Tamara D. Rozental, MD, David Zurakowski, PhD and Philip E. Blazar, MD