In addition to the anterior cruciate ligament, the other three knee ligaments are:
The posterior cruciate ligament (PCL) also links the thigh and shinbones inside the knee toward the back of the joint. PCL injuries are rare.
The medial collateral ligament (MCL) connects the two bones outside the joint on the inner side of your leg toward your other knee.
The lateral collateral ligament (LCL) runs on the outer knee opposite the MCL. It connects your thighbone to your fibula, the smaller bone in your calf.