Out of four main ligaments in the knee, the ACL is the major stabilizing ligament and is located in the centre of the knee, running from the femur (thigh bone) to the tibia (shin bone). A rupture occurs when the biomechanical limits of the ligament are over-stretched over its natural limits. ACL ruptures occur in common population as well as athletes. About 80% of ACL injuries are non-contact sports injuries and according to Hewett et al. (2005), women are more prone to suffer from it at a 4- to 6- fold greater rate than men.
The function of the ACL is the prevention of hyperextension (over- stretching the knee) and excessive anterior tibial translation in various degrees of flexion (Liu-Ambrose, 2003). 85% of the restraining force to anterior tibial displacement in 30 degrees of flexion and 90 degrees of flexion in the knee are provided by the ACL (Liu-Ambrose, 2003).
An ACL injury mostly occurs when pivoting or landing from a jump; So called high risk sports which either require a high rate of body-contact, quick changes of direction and neuromuscular control like football, basketball, tennis/squash, rugby and volleyball (Hewett et al., 2005), dancing, hockey and many more.
Whereas it is possible to be active regarding activities of daily life without an ACL reconstruction, high-demanding sports show a difficulty in performing them without an intact ACL.
There are several possibilities how to treat an ACL. Firstly, there is always the non- surgical, conservative way; meaning, that the patient does not have surgery, however, physiotherapy in combination with re-gaining full range of movement at the beginning and strengthening, proprioceptive training during a rehabilitation process is necessary to be able to deal with ADLs.
The surgical way, is performed to preserve the integrity of the knee as much as possible with replacing the ruptured ACL by a graft. Depending on the favor of the surgeon, there are different possibilities from which muscle the graft is taken (patella tendon, semitendinosus and gracilis tendon, quadriceps tendon). Different grafts are supposed to be more suitable for different sports (Macaulay, Perfetti and Levine, 2012).
Liu-Ambrose T., 2003, The anterior cruciate ligament and functional stability of the knee joint, Biomedical Journal, 45 (10), pp: 495-499
Hewett T.E et al., 2005, Biomechanical Measures of Neuromuscular Control and Valgus Loading of the Knee Predict Anterior Cruciate Ligament Injury Risk in Female Athletes
Macaulay A. A., Perfetti D. C. and Levine W. N., 2012, Anterior Cruciate Ligament Graft Choice, Sports Health, 4(1), pp: 63-68