Osteoarthritis of the knee is caused by a destruction or gradual rupture of the cartilage that protects the joint. Osteoarthritis of the knee is the most common form of osteoarthritis after 50 years of age. It is bilateral in two thirds of the cases. The causes of osteoarthritis are multiple: • Malformation of the legs (deformation of the axis of the piertas). • Genetic factors • Minor or major injuries • Sedentary • Obesity Knee osteoarthritis affects 20 to 30% of people between 60 and 70 years old and 40 to 50% of those 80 years of age and older. • Osteoarthritis of the knee most frequently affects women 50 to 60 years of age, obese, carriers of varicose veins in the lower limbs. • In all cases, it is important to perform some physical activity to maintain a good physical condition. The Orthoses for Osteoarthritis are designed for the treatment of osteoarthritis (mild, moderate or severe) associated or not with ligament instabilities.