In the knee, there are several structures: the collateral ligaments, the articular (joint) cartilages, the menisci and the cruciate ligaments. If there is injury to the knee, it is possible that more than one of these structures may be injured at the same time. There are two cruciate ligaments in the knee: the anterior (in the front) and the posterior (at the back).
The cruciate ligaments secure the stability in the knee in cooperation with other ligaments, the menisci and the muscles. Injuries to the anterior cruciate ligament are more common than injuries to the posterior cruciate ligament. The posterior cruciate ligament is most commonly damaged in connection with road accidents. When the posterior cruciate ligament is torn across, the shin bone will move backwards on the thigh bone. A lesion of the anterior cruciate ligament happens mostly in sporting situations where the foot is planted. If the anterior cruciate ligament is totally torn across, the knee may become unstable and the shin bone will move forwards on the thigh bone.