The knee is the largest and one of the most complex joints in the human body. On a yearly basis, near 12 million people visit orthopedic surgeons due to knee ligament injuries. The knee complex consists of 4 bones, multiple ligaments, muscles and tendons, cartilage and soft tissue. Knee ligaments connect bones to bones allowing for stability.
Ligaments of the knee are classified as cruciate and collateral ligaments. Ligaments connect bone to bone. The major ligaments of the knee consist of the ACL (anterior cruciate ligament, PCL (posterior cruciate ligament), MCL (medial collateral ligament) and LCL (lateral collateral ligament). Cruciate ligaments are within the knee joint. They prevent anterior (forward) and posterior (backward) translation of the femur from the tibia. Collateral ligaments are outside the knee joint and prevent medial (inside) and lateral (outside) instability.
Injuries to the collateral ligaments occur with the following stresses – Varus stress to the LCL (inside to outside force) or valgus stress the MCL (outside to inside force). High-risk sports include rugby, football, gymnastics, mixed martial arts and soccer. Many times these injuries in athletics occur from contact. Falls and twisting injuries can also cause damage to these ligaments. Injuries to these ligaments are called tears or sprains. Ligament sprains are classified on a severity scale called grades.