Trigger Finger and Thumb
Trigger finger is an often painful snapping, triggering, or locking of the
finger as it is flexed and extended. This is due to a localized inflammation
or a nodular swelling of the flexor tendon sheath that doesn't allow the tendon
to normally glide back and forth under a pulley. It occurs in the superficial
and deep flexor tendons adjacent to the A1 pulley at the metacarpal head (Figure
below). The thumb and the middle and the ring fingers of the dominant hand
of middle-aged females are most commonly affected. It is often encountered
in patients with diabetes and rheumatoid arthritis. The relationship of trigger
finger to repetitive trauma has been frequently cited in the literature; however,
the exact mechanism of this correlation is still open for debate.
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Symptoms |
Examination
The essential element in the physical examination is the localization of
the disorder at the level of the MCP joint. There is palpable tenderness,
and sometimes a tender nodule, over the volar aspect of the metacarpal head.
Swelling of the finger may also be noted. Opening and closing of the hand
actively produces a painful clicking as the inflamed tendon passes through
a constricted sheath. Passive extension of the DIP or PIP joint while keeping
the MCP joint flexed may be painless and done without triggering. With chronic
triggering, patient may develop IP joint flexion contractures. Therefore it
is important to determine whether there is normal passive range of motion
in the MCP and interphalangeal (IP) joints. Neurologic examination including
strength, sensation, and reflexes should be normal with the exception of severe
cases that are associated with disuse weakness and/or atrophy. Co-morbidities
can affect the neurologic exam as well (e.g., someone with diabetic neuropathy
may have impaired sensation).
Functional Limitations
Functional limitations include difficulty with grasping and fine
manipulation of objects due to pain, locking, or both. The patient may have
problems with typing, buttoning a shirt, driving a car, using tools at work,
etc.
Diagnostic Studies
This is a clinical diagnosis. Patients without a history of injury or
inflammatory arthritis do not need routine radiographs. MRI can confirm
tenosynovitis of the flexor sheath, but this offers minimal advantage over
clinical diagnosis.
Differential Diagnosis
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Anomalous muscle belly in the palm |
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Dupuytren's disease |
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Ganglion of the tendon sheath |
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Tumor of the tendon sheath |
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Rheumatoid arthritis |
Treatment
The initial goal of treatment is to restore the normal gliding of the tendon
through the pulley system. This can often be achieved with conservative
treatment. However, typically the first line of treatment is a local steroid
injection. The determination whether to inject first or try non-invasive
measures is often based on the severity of the patient's symptoms (more severe
symptoms generally respond better to injections), the level of activity of the
patient (e.g., someone who needs to get back to work as quickly as possible)
and the patient's and clinician's preferences.
Non-invasive measures generally involve splinting the MCP joint at 10 to
15 degrees for up to 2 weeks. This has been reported to be quite effective,
although less so in the thumbs. Also, DIP splinting provides a reliable and
functional means of treating work-related trigger finger without lost time
from work. Additional conservative treatment includes icing the palm (20 minutes
2 to 3 times per day in the absence of vascular disease), NSAIDs/COX-2 inhibitors,
and avoidance of exacerbating activities. Wearing padded gloves provides protection
and may help to decrease inflammation by avoiding direct trauma.
Rehabilitation may include treatment with an occupational or physical
therapist experienced in the treatment of hand problems. Supervised therapy is
generally not necessary but may be useful in the following scenarios:
(1) when a patient has lost significant strength, range of motion, and/or
function from either not using the hand, from prolonged splinting, or
post-operatively;
(2) when modalities such as ultrasound or iontophoresis are recommended to
reduce inflammation; and
(3) when a customized splint is deemed to be necessary.
Therapy should focus on increasing function and decreasing inflammation and
pain. This can be done by utilizing techniques such as ice massage, contrast
baths, ultrasound, and iontophoresis with local steroid use. For someone with a
very large or small hand or other anatomic variations (e.g., arthritic joints),
a custom splint may fit better and allow him or her to function at work more
easily than a pre-fabricated splint. Improving range of motion and strength can
be done via supervised therapy either prior to surgery or postoperatively.
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Procedures A local steroid injection (Figure right) can be used as an alternative
or in addition to other management. The steroid injections are usually
beneficial and frequently curative. However, they may need to be repeated
up to 3 times. This procedure is less effective with multiple digits
involvement (such as in patients with diabetes or rheumatoid arthritis)
or when the condition has persisted greater than 4 months. |
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Surgery
Although steroid injections should be tried for most trigger finger cases
prior to considering surgery, surgical intervention is highly successful for
conservative treatment failures and should be considered for patients desiring
quick and definitive relief from this disability. Individuals with diabetes
and rheumatoid arthritis are more likely to require surgery. There are two
general types of surgery for this condition: the standard operative release
of A1 pulley and the percutaneous A1 pulley release procedure. Both surgical
procedures are generally effective and carry a relatively low risk of complications.
Potential Complications
Disease-related complications include permanent loss of range of motion from
a contracture developing in the affected finger—most commonly at the PIP joint.
In rare instances, chronic intractable pain may develop despite treatment.
Potential Treatment Complications from NSAIDs are well known (gastric, renal, and hepatic). COX-2 inhibitors may have fewer gastric-associated side effects. Complications from local steroid injections include skin depigmentation, skin atrophy, tendon rupture, digital sensory nerve injury, or infection. Individuals with rheumatoid arthritis are more likely to have tendon rupture; therefore, repeated injections are not recommended in these cases. Possible surgical complications include infection, nerve injury, and flexor tendon bowstringing.
