The knee may be dislocated at birth.
Although rare, a dislocated knee in a newborn may be related to the position in the womb before birth. This defect can also occur in children who have Larsen syndrome, which consists of many dislocated joints (elbows, hips, and knees), clubfoot, and characteristic facial features (such as a prominent forehead, sunken nose, and wide-spaced eyes). It can also occur in children who have arthrogryposis multiplex congenita.
When the infant is examined, doctors find that the leg cannot be bent more than a few degrees. Immediate treatment with physical therapy (daily flexing the infant's leg) and splinting the leg in a bent position usually results in a functional knee. Treatment is more complex in infants who have Larsen syndrome, arthrogryposis multiplex congenita, or other problems.