It is a very common and debilitating disease where there is conflict between the patella and the trochlea (femur region in constant contact with patellar cartilage). Consequently, the patellar joint, fully lined with cartilage, undergoes a wear process ranging from softening (grade 1) to total destruction exposing underlying bone (grade 4). Types of chondromalacia are numerous, mainly traumatic, due to a specific contusion episode triggering the wear process, and hyperpressure patellofemoral chondromalacia, caused by a pre-existing alteration usually resulting from a tendency of the patella to "run" out of its normal axis.