used today.) the medial collateral ligament (or "tibial collateral ligament") Component injuries The anterior cruciate ligament The anterior cruciate ligament is one of the four crucial ligaments in the knee. It originates from the lateral condyle of the femur and goes to the intercondyloid eminence of the tibia. Its function is to provide stability in the knee and minimize stress across the knee joint. It also restrains excessive forward movement in the leg and limits rotational movements in the knee. Injury An anterior cruciate ligament injury results from excess tension on the ligament. This can come from a sudden stop or twisting motion of the knee. A few initial symptoms include swelling, knee instability, and pain. A popping sound or sensation may or may not be heard when the ACL first tears. A following symptom usually includes the feeling of the knee "giving out". Tearing of the ACL is the most significant injury because it leaves the knee unstable, which also causes the knee to lose its normal function. Epidemiology It is estimated that 100,000 new anterior cruciate ligament injuries occur in the U.S. each year. Approximately half of the new ACL injuries involve injuries to the ligament, tendon, and or muscle of that affected knee. Women are at greater risk for ACL injuries than men due to their greater Q angle. The Q angle is the angle formed by a line drawn from the anterior superior iliac spine to central patella and a second line drawn from central patella to tibial tubercle. Meniscus The medial meniscus is a C-wedge shaped piece of cartilage that acts as a"shock absorber" between the femur and the tibia. Each knee has two menisci, one at the outer edge and one at the inner edge of the knee. The menisci are tough and rubber-like to help cushion the joint and help keep it stable. The lateral meniscus is also known as the external semilunar fibrocartilage. It is a fibrocartilage band on the lateral side of the knee joint and can easily be injured with torsional stress or direct force. Each knee has a medial and lateral meniscus, consisting of connective tissue and collagen fibers. Menisci are needed to distribute the body weight across the knee. Without them, the body weight is distributed unevenly on the femur and tibia, possibly leading to early arthritis in the knee joint. The menisci are nourished by small blood