Among the injuries most often suffered by soccer players, anterior cruciate ligament (ACL) rupture of the knee is the most incapacitating ; during the first half of the 2006-2007 championships of football leagues 1 and 2 of France, no fewer than 10 ACL ruptures were recorded.

Ligaments constitute veritable ″anchoring systems″ stretched from one bone to another. They allow the joint’s surfaces to remain in contact during movement and thus maintain the joint’s stability. The central pivot of the knee is made up of anterior and posterior cruciate ligaments (ACL and PCL, respectively). These ligaments provide stability and ensure the kinematics of the knee.

Most complete or partial ruptures of the ACL are engendered by sports involving pivoting. If the injury is not adequately cared for, insecurity and instability will result when the patient returns to the playing field.

ACL rupture is usually easily diagnosed through clinical tests, mainly the Lachman and drawer tests. But clinical diagnosis has the drawback of not being quantifiable, given that it depends upon both the level of experience of the examiner and upon the degree of muscle relaxation of the patient.

Several laxity measurement systems are available, but they all remain dependent upon both the operator and upon the degree of muscle relaxation of the patient. This is why the invention of a new laxity measurement system, independent of both operator and patient, is of great significance.