[Pollex flexus congenitus]

The authors report on the incidence, clinical picture, etiology, pathogenesis and treatment of congenital pollex flexus, and communicate the results of surgery on 52 thumbs. The permanent flexion anomaly in the interphalangeal joint and a hard, palpable knot in the long flexor tendon of the thumb over the metacarpophalangeal joint are typical for the deformity. Although these changes are sometimes observed immediately post partum, delayed diagnosis and treatment are more common. The hypothesis that it is a hereditary, endogenous condition is supported by observations in twins, relatively frequent bilateral occurrence and a high familial incidence. Constriction of the synovial sheath over the basal joint of the thumb is a key pathogenetic factor, although little is known about its causes; anatomical factors, influences affecting the growth of the sesamoid bones, and mechanical causes have been postulated. A more plausible hypothesis was first advanced by Jeannin. Like Hueston and Wilson 100 years later, he compared the tendon to a thick thread which had to be passed through a narrow eye of a needle: as a result, the "thread" would be frayed and compressed. The knot in the tendon is held to be a secondary phenomenon. The pathologicoanatomical picture varies. Lymphocyte and monocyte infiltration, and metaplasias to fiber cartilage have been detected in specimens excised from the tendon and the synovial sheath. However, pathologic changes have not been found in all cases. In the first year of life conservative therapy may be attempted, with temporary splinting of the thumb following manual correction of the flexion anomaly in the interphalangeal joint.(ABSTRACT TRUNCATED AT 250 WORDS)