Ligaments are strong, dense structures made of connective tissue that help in stabilizing joints. The anterior cruciate ligament (ACL) is one of four major ligaments to make up the human knee. It is critical to knee joint stability, especially for athletes in cutting sports. A tear to the ACL results from the over-stretching of this ligament within the knee. ACL injury occurs with a 4- to 6-fold greater incidence in female athletes compared with male athletes (Hewett et al, 2006). The fact that this injury occurs more frequently in females has fueled research as to why this is the case. This paper will discuss in detail where the anterior cruciate ligament is located and what its function is within the knee. It will then go into mechanisms of injury and common sports in which the ACL tear occurs for females. I will then discuss possible reasons why this injury occurs more in females than in males, focusing on a correlation with the menstrual cycle. Surgical reconstruction and recovery rates will be touched upon, as well as injury prevention techniques. BODY:
The knee is a hinge joint that brings together three bones. These bones are the femur, which is the primary leg bone, the tibia, which is the lower leg bone, and the knee cap, also known as the patella. These bones come together to make the knee and are held together by ligaments. As mentioned, the ACL is one of four ligaments that make up the knee joint. Along with the anterior cruciate ligament, the posterior, medial, and lateral cruciate ligaments all contribute to the stabilization of the knee. The anterior cruciate ligament is responsible for the backward and forward motion of the knee, particularly it restrains the excess forward movement of the knee (Dugan, 2005).
ACL injuries can result in a complete tear of the ligament, as well as a partial tear of the ligament. ACL’s most commonly tear during full weight bearing activities. Most ACL injuries occur in a rotational way, during the twisting of the knee. When this occurs, it is usually a non-contact injury. Females tend to be more ligament dominant, rather than muscle dominant. Because the ligaments of women tend to be smaller and weaker compared with a man's, women are more prone to a higher rate of ligament injury. Beck and Wildermuth found that females are more vulnerable to non-contact injuries (Ireland et all, 1997). The signs and symptoms of an ACL tear are very unique and can usually indicate exactly what has happened. The injured person will usually hear a loud pop, have joint line swelling, and a decrease in proprioception (Powell & Barber-Foss, 2000). The knee will feel unstable and give out spontaneously because the stabilizers are missing. Once an ACL has been torn, it must be surgically repaired in order for a healthy recovery. The knee does not get a sufficient blood supply on its own to heal its torn ligaments and so it must be surgically replaced by one of three grafts. These options include a hamstring tendon graft, a patellar tendon graft, or a cadaver graft. All three surgeries are similar in that the torn ACL is removed and replaced, however scar length tends to vary by surgery. Most doctors have their suggestions on what they like best, but all three seem to heal in a similar manner to one another with a very high success rate. 90-95% of patients who undergo this surgery can expect to return to full sports participation within six months (Hewett, 2000).
There are multiple factors that influence non-contact ACL tears and these factors can be separated into intrinsic and extrinsic mechanisms. Intrinsic mechanisms are things we cannot control. The size of the ACL, the neuromuscular firing order, and hormonal influences are a few examples of intrinsic factors that can increase ACL injury rate. The extrinsic factors are potentially controllable and include strength and conditioning, shoes, and proper form in...