The knee is a hinge joint in which the end of the femur links to the top of the tibia. The four major ligaments that stabilize the knee are the M.C.L., L.C.L., P.C.L. and the A.C.L. The medial collateral ligament (M.C.L.) and the lateral collateral ligament (L.C.L.) cover the inner and outer sections of the knee. They prevent the joint from bending inward and outward. The Posterior cruciate ligament runs from the anterior of the femur to the posterior of the tibia. The anterior cruciate ligament runs from the anterior of the tibia to the posterior of the femur. These two ligaments form and "X" within the knee, which stabilizes the tibia beneath the femur and limits the rotation of

Before a patient is sent for an M.R.I. which includes high expenses and a long waiting period, three popular tests are used to nearly confirm the injury. The First is the Anterior Drawer Test. In this test the patient lies on their back, bends their knee up to 45-90 degrees. The doctor will stabilized the foot and place one hand on either side at the top of the tibia. The doctor will then pull forward searching for an "endpoint". This would mean that the A.C.L. would still have some sort of attachment. Everyone should have a small amount of movement here, but with a healthy A.C.L. will always have an "end point". In 147 cases with diagnosed chronic cruciate ligament in sufficiency, the results were positive in 79.6% of the patients (6). The second test is the Lachman Test. In this test the patient will again lye on their back with their knee between 0 and 15 degrees. the doctor will push down on the femur, while pulling up on the tibia and vise versa. A "soft or mushy" end feel indicates a positive test for A.C.L. tear. A Negative test would give a "hard or definite feeling at each end. This is more effective with positive test success between 80 and 98%. The third test in the Pivot shift test. The patient lies on their back with their knee raised and bent slightly. The patient must then completely relax in the doctors arms. The doctor will then place one hand lateral on the ankle and the other hand lateral but at about the mid-calve. The doctor guides the through a circular rotation applying pressure when the knee reaches certain points. If there is a feeling of giving there is an injury to one of the ligaments. Depending on where the knee gives way will detect what type of injury it is. Under anesthesia, this test is between 82 and 98% accurate. Without anesthetic it's only between 10and 35% accurate.

the tibia.(1) The size and strength of the ligaments will depend on the size and the make up of the individual. On average, the length of the ACL is between 28 and 34 mm, the width between 8 and 12mm, and between 4 and 6 mm thick (2). Within this structure there are numerous non-parallel fibers that together behave as three evident bundles (antermedial, posterolateral and intermediate). Variations in the lengths of their fibers and the ability of the A.C.L. to rotate slightly make flexion and tension of the leg possible (3).

When the A.C.L. is stretched, there may be few to no signs that there is a problem. If the A.C.L. is partially torn the knee will usually feel slightly unstable, there will be a moderate amount of pain and substantial swelling. When an A.C.L. completely tears there is normally a very loud "pop", the athlete will be unable to return to play, and there will be a constant throbbing pain that increases with movement. In this case there will be an exorbitant amount of swelling around the knee and possible bruising(3) The only way that there can be 100% certainty of an A.C.L. tear is through an M.R.I. (magnetic resonance imaging). This type of image of the knee shows the outlines of muscles, tendons and ligaments as well as the bones that would be seen on an x-ray. The image below is an M.R.I. of a healthy knee, where the red is the A.C.L.

About 15% of people can survive without an A.C.L., because the other ligaments and muscles surrounding the knee can compensate. In order to have the optimum possible stability the patient is directed to strengthen the hamstrings as much as physically possible. The hamstring assists in some of the roles of the A.C.L., but can never take over the role of the A.C.L. An increase in the hamstring strength will help reduce further instability, therefore preventing further damage to the knee. If the patient has already tested positive in

Some topics in this essay:
Lachman Test, PCL ACL, ACL September, , Drawer Test, Knowing ACL, patella tendon, acl injury, acl stretched, test patient, blood supply, hamstring strength, tear acl, cruciate ligament, hamstring tendon, acl tear, section hamstring tendon, ligament runs anterior, test patient lies, direction change acl, cruciate ligament runs,