The initial symptom is of a painless "click" in the hand on moving the fingers which might eventually progress into a locked finger. The finger might be locked in flexion, whereby a forceful extension of the finger is required to unlock the finger , causing a feeling of "triggering" at the base of the finger (the metacarpo-phalangeal joint). Patients may or may not notice a lump or knot in the palm of the hand, again typically at the base of finger.
The problem occurs when there is a constriction where the finger flexor tendon enters the tendon sheath at the base of the finger. It is caused either by a thickening (hypertrophy) of the tendon sheath, or a nodular swelling of the tendon itself just proximal to the sheath. Either way, the basic problem lies in the discrepancy between the size of the tendon nodule and the thickened tendon sheath. This means that the tendon can no longer slide easily through it and it becomes harder to bend or straighten the affected finger or thumb as a result.
Trigger finger occurs two or three times more frequently in women than in men and has a peak incidence of around 40- 60 years of age (the demographics sounds similar to carpal tunnel syndrome... ) The ring finger is the most frequently involved, followed by thumb and ring finger.Frequently one finds that multiple fingers are affected and bilateral hand involvements are not uncommon.
As many as 85% of trigger finger can be successfully treated non-operatively. These include activity modification, splinting, anti-inflammatory drugs (NSAIDs) and steroid injections.
Steroid injection around the flexor sheath can be an effective treatment, and in my experience, for the patients with mild triggering and short duration of symptoms, one can expect a complete resolution of symptoms.
Surgical release of trigger finger is reserved for patients not responding to conservative management, the chronically locked finger, long duration of symptoms, and multiple digit involvement. As with most of my minor hand surgery cases, this can be done as a daycare procedure under local anaesthesia and takes about 15 minutes. However, in instances where multiple fingers need to be operated upon, general anaesthesia may be a more comfortable option.
Similar to carpal tunnel release, a small incision about 1cm is made at the base of the affected finger and the constricting sheath is then cut open longitudinally under direct vision. Care is taken to ensure that the nerves running alongside the tendon is not disturbed, and this can only be done if the surrounding structures are well visualized; this is the reason that I am not in favour of percutaneous release of trigger finger, although the proponents say that it is a reasonably safe option.
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| A surgical loupe is frequently needed to identify the structures |
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| Incision at the base of the finger |
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| the constricting sheath (A1 pulley) is visualized and divided |
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| sutured up |
Trigger finger in infants or children almost always involves the thumb and could be a different entity from the adult type. Most authors recommend observation as children below 6 months can have spontaneous resolution of symptoms ( I know, because my nephew had the same problem - it resolved spontaneously!). Surgery, as with adults, could be considered if symptoms persist.
- the BomohTulang -
References:
Trigger digits: diagnosis and treatment. J Am Acad Orthop Surg. 2001 Jul-Aug;9(4):246-52.
Trigger digits: principles, management, and complications. J Hand Surg Am. 2006 Jan;31(1):135-46.
The Natural History of Pediatric Trigger Thumb. The Journal of Bone and Joint Surgery-American Volume
Issue: Volume 90-A(5), May 2008, pp 980-985
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