Congenital Laxity of the Ligaments with Hypotonia

Extreme mobility of the joints is of great advantage to an acrobat, permitting him to assume fascinating postures. When the condition appears in infancy, however, it may be quite alarming, as it may easily be confused with serious organic disease if the features are not known. There are two basic disturbances in this condition: (1) Abnormal mobility of the bones at the joints, and (2) extreme hypotonia of the muscles. In describing their cases, orthopaedic surgeons have tended to emphasize the former aspects, while physicians have tended to emphasize the latter. The majority of recorded cases have appeared in the American literature, the first author to draw attention to this anomaly in infancy being Finkelstein, who in 1916 described a 21-month-old child with extreme mobility of all the joints and marked hypotonia. He carefully distinguished the condition from Oppenheim's disease by the fact that there was no gross neurological disturbance in his case, the reflexes were normal and the electrical reactions of the muscles were normal. He called the condition 'joint hypotonia'-an obvious misnomer. Sobel (1926) suggested the term 'essential or primary hypotonia', while Key (1927), Michaels and Searle