- "Trigger finger" can also mean the finger which is used to operate the trigger of a gun or of a power tool.
Trigger finger, trigger thumb, or trigger digit, is a common disorder of later adulthood characterized by catching, snapping or locking of the involved finger flexor tendon, associated with dysfunction and pain.[1] A disparity in size between the flexor tendon and the surrounding retinacular pulley system, most commonly at the level of the first annular (A1) pulley, results in difficulty flexing or extending the finger and the “triggering” phenomenon.[2] The label of trigger finger is used because when the finger unlocks, it pops back suddenly, as if releasing a trigger on a gun.
Etiology
Multiple potential causes have been described but the etiology remains idiopathic, meaning that the cause is unknown.[3] It has also been called stenosing tenosynovitis (specifically digital tenovaginitis stenosans) but this may be a misnomer as inflammation is not a predominant feature.
Some speculate that repetitive forceful use of a digit leads to narrowing of the fibrous digital sheath in which it runs, but there is no data to support this theory and it may unfairly stigmatize hand use. The relationship of trigger finger to work activities is debatable and scientific evidence for[4] and against[5] hand use as an etiological factor are sparse and of low quality.
Natural history
The natural history of disease for trigger finger remains uncertain.
There is some evidence that idiopathic trigger finger behaves differently in patients with diabetes.[6]
Clinical Evaluation
Diagnosis is made almost exclusively by history and physical examination alone. More than one finger may be affected at a time, though it usually affects the thumb, middle, or ring finger. The triggering is usually more pronounced in the morning, or while gripping an object firmly.
Treatment
Injection of the tendon sheath with a corticosteroid is effective over weeks to months in more than half of patients.[7]
When corticosteroid injection fails, the problem is predictably resolved by a relatively simple surgical procedure (usually outpatient, under local anesthesia). The surgeon will cut the sheath that is restricting the tendon. Anecdotally, patients who respond at least transiently to corticosteroid injection are more likely to respond to surgical treatment.
One recent study in the Journal of Hand Surgery suggests that the most cost effective treatment is two trials of corticosteroid injection, followed by open release of the first annular pulley.[8] Choosing surgery immediately is the most expensive option and is often not necessary for resolution of symptoms.[9]
Investigative treatment options with limited scientific support include: non-steroidal anti-inflammatory drugs, occupational or physical therapy, steroid iontophoresis treatment, splinting, therapeutic ultrasound, phonophoresis (ultrasound with an anti-inflammatory dexamethasone cream), and Acupuncture.
Recovery
Recurrent triggering is unusual after successful injection and rare after successful surgery.
Difficulty extending the proximal interphalangeal joint may persist for months and benefits from exercises to stretch the finger straighter.
References
- ^ Makkouk et al. Trigger finger: etiology, evaluation, and treatment. Curr Rev Musculoskelet Med (2008) vol. 1 (2) pp. 92-6
- ^ Makkouk et al. Trigger finger: etiology, evaluation, and treatment. Curr Rev Musculoskelet Med (2008) vol. 1 (2) pp. 92-6
- ^ Makkouk et al. Trigger finger: etiology, evaluation, and treatment. Curr Rev Musculoskelet Med (2008) vol. 1 (2) pp. 92-6
- ^ Gorsche R, Wiley JP, Renger R, Brant R, Gemer TY, Sasyniuk TM. Prevalence and incidence of stenosing flexor tenosynovitis (trigger finger) in a meat-packing plant. J Occup Environ Med. 1998 Jun;40(6):556-60.
- ^ 1: Kasdan ML, Leis VM, Lewis K, Kasdan AS. Trigger finger: not always work related. J Ky Med Assoc. 1996 Nov;94(11):498-9. PMID: 8973080
- ^ Journal of Bone and Joint Surgery (American). 2007;89:2604-2611.
- ^ Journal of Bone and Joint Surgery (American). 2007;89:2604-2611.
- ^ Kerrigan CL, Stanwix MG.Using evidence to minimize the cost of trigger finger care.J Hand Surg Am. 2009 Jul-Aug;34(6):997-1005. PMID: 19643287
- ^ Kerrigan CL, Stanwix MG.Using evidence to minimize the cost of trigger finger care.J Hand Surg Am. 2009 Jul-Aug;34(6):997-1005. PMID: 19643287
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