Congenital dislocation of the patella may occur as an isolated entity or in concert with syndromes such as nail-patellasyndrome. The hallmark features of congenital patellar dislocation are fixed flexion deformity of the knee, limited active knee extension, genu valgum and external tibial rotation. Secondary to external tibial rotation the position of the tibial tuberosity is abnormally lateral. Congenital dislocation of the patella must be differentiated from the much more common recurrent patellar dislocation which presents in late childhood or early adolescence and is due to simple patellar malalignment. The ability to maintain a normal patellar position after surgical realignment is influenced by the amount of patellar hypoplasia and size of the distal femoral trochlear groove. Congenital dislocation of the patella requires surgical correction. If the patella is very small and the trochlear groove is very shallow it may be more difficult to achieve stability of the patella.