Trigger thumb in infancy and childhood. A survey of 80 patients.

TRIGGER THUMB in adult life is often associated with a history of trauma and occurs almost exclusively in middle aged female patients (Fahey and Bollinger, 1954). In infancy and childhood trigger thumb is a relatively rare condition, the aetiology of which is obscure. The condition is not well known outside hospital practice. It seems worth while to review the cases of trigger thumb operated on in infancy and childhood in the hope that some light might be thrown on the condition as it affects this younger age group. The review is based on a series of 80 patients treated in the Royal Hospital for Sick Children, Edinburgh, during the eighteen year period, January 1946 to December 1963. We were impressed that in 23 patients out of 80, or 29 per cent, the condition was bilateral. Overall the condition was seen in 103 thumbs. In the well established case there is a thickening and stenosis of the sheath of the flexor pollicis longus tendon at the level of the metacarpo-phalangeal joint of the thumb. In addition there is a nodule in the tendon itself and the disparity in size between the tendon and the narrowed sheath limits the movement of the tendon and consequently of the distal phalanx of the thumb to the base of which the tendon is inserted. If the primary lesion is a narrowing of the tendon sheath this could cause pressure on the tendon, exerted more consistently in the position of rest, i.e. about 15 degrees short of full extension, and the movement of the tendon through the narrowed sheath could damage the tendon and cause the development of a nodule. Biopsy studies on the thickened tendon sheath have confirmed the findings of others (Fahey and Bollinger, 1954; Torokova, 1963), that the thickening in the tendon sheath consists of non-specific fibrous tissue. The nodule in one instance where biopsy was taken also consisted of similar non-specific fibrous tissue. In two patients where the condition had existed for a considerable time, the nodule contained glairy, ganglion-like fluid, possibly the result of degeneration. A considerable number of patients presenting with the established condition on one side later reported with the same condition in the opposite thumb. We have examined the normal thumb carefully in all patients presenting with unilateral symptoms and also in those patients seen at follow-up where operation has been performed on one side. In 9 patients we found a definite nodule in the