The knee is a hinge joint that connects the thigh bone (femur) to the lower leg bones (tibia and fibula) and the kneecap (patella). Like other joints in the body, the knee is made up of tendons and ligaments, as well as cartilage structures like menisci and bursae. The tendons and ligaments provide strength and stability and allow the knee to evenly carry the weight of the body, while the cartilage structures allow for smooth, fluid movements.
Mechanism Of Injury
The knee may become injured as a result trauma, overuse or degeneration that occurs naturally over time. Injuries can affect any structures within the knee, resulting in a bruise, sprain, strain or fracture. After a knee injury, patients may experience knee pain that varies in frequency and severity, as well as difficulty walking or standing, stiffness and loss of motion.

While knee injuries can affect patients of all ages and activity levels, they are most common in those who participate in high-risk sports, are obese, are older and who lack muscle strength and flexibility.

ACL Injuries Treatment
The ACL (anterior cruciate ligament) is one of the most commonly injured ligaments in the knee. Running diagonally through the middle of the joint, the ACL works together with three other ligaments to connect the femur (upper leg bone) to the tibia (lower leg bone). People who play sports that are likely to damage the knee — such as basketball, football, skiing and soccer — are at greatest risk for injuring the ACL. Only about 30% of ACL injuries result from direct contact with another player or object. The rest occur when the athlete decelerates while cutting, pivoting, or sidestepping; lands awkwardly; or plays recklessly. About half of ACL injuries are accompanied by damage to the meniscus, cartilage, bone or other ligaments in the knee.

Signs that you may have injured your ACL include pain, swelling and instability immediately after the injury, followed hours later by greater swelling and pain, limited motion, tenderness and an inability to walk comfortably.

Only about a third of people with a completely torn ACL are able to build their muscle strength enough to resume normal activities without surgery. Those who are not very active may choose a strengthening program instead of surgery, since the injury is not likely to interfere with their daily activities.

Active, athletic people are more likely to opt for surgery, so that the knee can be repaired and rehabilitated and they can return to their activities. The surgery is called an arthroscopically assisted ACL reconstruction and is performed in an outpatient setting.