Congenital hyperextension of the knees in twins.

Bilateral congenital hyperextension of the knees occurring in dizygotic twins is reported. Twin A had the mild form of the disease, genu recurvatum, while twin B had a more severe form of the disease, congenital subluxation. Hyperextension of the knee may occur as a sporadic abnormality, in conjunction with multiple dislocations or as a feature of a syndrome. Early detection and diagnosis are important, especially in the more severe forms of the condition, subluxation and dislocation, which require aggressive immediate intervention to prevent long-term sequelae. Conservative treatment consisting of manipulations and immobilization usually will correct the mild forms of the condition if instituted soon after birth. Prognosis is less favorable with delayed treatment, in the presence of other congenital anomalies, and with genetic syndromes.