Risk for patients Risk for the patients will be the risk related to the surgical procedure. They include anesthetics (local or general), procedure-related risk such as infection, deep venous thrombosis, damages of anatomical structures. It is important to underline that all these risks are not specifically related with this procedure, but with all the procedures involving an ankle arthroscopy with cartilage treatment. The risks for the patients will be minimized with specific training activities for all the personnel taking part to the project (i.e nurses, operating room personnel, attending surgeons, hematologists, residents) . Data will be evaluated by a statistician , and all the monitoring activities will be performed by dedicated personnel.