 To investigate the effect of tourniquet application on the coagulation system in patients undergoing a knee arthroscopy. A finding of more prominent activation of the coagulation system with tourniquet use than with non-use will create an important opportunity to prevent thromboembolic events in these patients, as it has been shown that knee arthroscopy can be performed adequately without the use of a tourniquet. Furthermore, it will increase the understanding of the pathophysiology of thrombosis. 