Hyperextension of the Knee

Following an uneventful pregnancy, a 25-year-old woman was delivered of an infant girl by repeat cesarean birth with occiput anterior presentation at 39 weeks gestation. The deformity was readily evident at birth.

The neonate's left leg appeared to be plastered onto the anterior trunk; a result of the fetus' position in the uterus. The left knee could be flexed to only 90 degrees and hyperextended to 35 degrees. Within 2 days and without any specific treatment, the knee's range of motion became normal-a testament to the resilience of newborns.

Obtain plain films or ultrasound studies to evaluate an infant with congenital knee dislocation for possible coexisting hip dislocation. Roentgenograms of this patient's left knee, leg, and hip revealed no bony abnormalities or dislocations.