According to the authors, the anterior cruciate ligament (ACL) is the most commonly injured ligament in the body for which surgery is frequently performed. This probably underestimates the problem because of failure to make the diagnosis. Women in sports appear to have a higher incidence of injury than do men, perhaps due to differences in leg alignment (increased incidence of “knock knee”), less space within the knee joint for the ligment, hormonal factors that would weaken the ligament, and perhaps less overall joint control during vigorous activities. Regardless of whether a person is a male or female, the injury leads to an increased incidence of “premature” knee osteoarthritis.
ACL tear is very often accompanied by other injuries, including those to a meniscus, joint cartilage, bone, and other ligaments. When the injury occurs, sometimes it is obvious, because of the mechanism of injury and/or hearing an audible popping sound, swelling from bleeding into the knee, and lack of function. When the ligaments on the sides of the knees (“collateral” ligaments) are injured, they generally do not cause swelling, and meniscal tears show delayed swelling.
The diagnosis may be made by the history, supplemented by a Lachman test (in which the lower leg is pulled anteriorly against a fixed femur, to detect instability) and, when necessary, magnetic resonance imaging (MRI) examination. In the acute phase of injury, the victim may be able to walk normally and perform “straight-plane” activities, such as stair climbing, biking, and even jogging. However, if he or she is unstable in normal activities or wishes to resume activities that call for cutting motions and pivoting, or is engaged in a profession or activity in which complete stability of the knee is essential (and safe), then surgery may be required.
In the acute phase of injury, the knee should be treated as would any other ligament injury, with rest, ice compression and elevation. Bracing or taping the knee may be helpful. Surgery may not be advised for a period of weeks, until the bleeding has subsided and the joint swelling receded.
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