Trigger Thumb
May 1, 2008 by Dr Arun Pal Singh
Filed under Pediatric Disorders
Trigger thumb or stenosing tendovaginitis of the flexor pollicis longus, is a relatively rare deformity in which the fibrous tendon sheath is thickened and constricted.
There is a palpable nodule on the volar aspect of the thumb in the region of the metacarpo-phalangeal joint.
The incongruity of the tendon’s surface interferes with its normal gliding within its sheath. Snapping or triggering results from the blockage of the tendon prominence against the constricted sheath and the sudden release following application of passive force and passage past the obstruction.
In most cases the thumb is locked in flexion, but occasionally it may be locked in extension. The nodule is not painful. The infant or child has no complaints. It is the infant or child has no complaints. It is the concern of the parents that brings the patient to the surgeon.
In about 25 percent of cases, the trigger thumb is noted at birth. This congenital form resolves spontaneously within 12 months in about 30 percent of cases.
Involvement is bilateral in about 50 percent of the cases noted at birth.
The childhood form develops later on, between 6 and 30 months of age, and has a spontaneous recovery rate of about 12 percent.
The etiology is unknown.
Treatment
Gentle passive stretching exercises can be performed several times a day; they do no harm provided they cause the infant no pain.
Part time splinting of the thumb in extension may help. Full-time splinting should not exceed three weeks because of the possibility of locking in the reverse direction.
Hydrocortisone injection into the thickened fibrous sheath and nodule has not succeeded; it is not fair to try a painful invasive method of treatment when previous experience has demonstrated lack of success.
Because of the possibility of spontaneous recovery it is wise to postpone operation on the trigger thumbs until the child is two years of age.
Operative treatment consists of simple surgical release of the fibrosed tendon sheath through a transverse incision in the flexion crease of the metacarpophalangeal joint of the thumb.
The operation should be performed before the child is four years of age.
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