The knee joint consists of the thigh bone (femur), shin bone (tibia), and kneecap (patella). Various ligaments connect these bones and stabilize the joint. Within the knee, there are four main ligaments that hold the bones together and keep them stable. In addition to these main ligaments, the anterior and posterior cruciate ligaments cross each other in an 'X' shape inside the knee joint. These cruciate ligaments control the forward and backward movements of the knee. Specifically, the anterior cruciate ligament (ACL), which runs diagonally through the center of the knee, prevents the shin bone (tibia) from sliding forward in front of the thigh bone (femur), thereby providing rotational stability to the knee.