The main concern of this chapter presents the congenital deformities of the knee. Congenital hyperextension of knee and congenital flexion deformities of the knee are two types of congenital deformities of the knee. The incidence of congenital hyperextension deformity is less than 0.1%. It has been diagnosed by the presence of hyperextension of knee and confirmed by ultrasonography. Positional knee flexion contracture, congenital dislocation of the patella and congenital knee flexion contracture are the different congenital flexion deformities of the knee. Positional knee flexion contractures may initially be up to 45°. If further knee flexion and quadriceps function are normal with no other neurologic or dysmorphic features, it can be assured that the flexion contracture will resolve in the first few months of life. Congenital dislocation of the patella is an entity in which the patella is dislocated at birth. Treatment of a congenital knee flexion contracture involves a careful assessment of all lower extremity deformities as well as the neurodevelopmental status of the patient.