Congenital dislocation of the patella.

Congenital dislocation of the patella may occur as a persistent lateral dislocation of the patella that presents with a knee flexion contracture and the patella tethered lateral to the femoral condyles or as an intermittent dislocation of the patella. In the latter syndrome, the patella dislocates completely with each flexion and extension cycle of the knee and is best termed obligatory dislocation of the patella, because the patient has no control over the patella dislocating as he or she moves the knee. The first type of congenital dislocation, which is fixed, often is associated with syndromes such as arthrogryposis and should be corrected surgically by lateral release and realignment of the patella. Obligatory dislocation of the patella tends to be an isolated dysplastic anomaly and may be relatively well tolerated. Rebalancing of the patella usually is done at a later age because of less interference with function. The current author describes the natural history of patella femoral dysplasia, detailing the pathologic changes that are present, and recommends surgical techniques for correcting both types of congenital dislocation of the patella.