Injuries to the posterior cruciate ligament—which is located in the back of the knee—typically result from a powerful force or trauma in the region. This ligament, which connects the thigh bone (femur) to the shin bone (tibia), keeps the tibia from moving too far backwards. Common causes of posterior cruciate ligament injuries such as sprains or tears include motor vehicle accidents (e.g., a bent knee hitting a dashboard) and sports-related trauma (e.g., a football player falling on a bent knee). Sprains and tears of the posterior cruciate ligament are much less common than other knee ligament injuries, and thus are often difficult to evaluate. In many cases, this type of injury occurs in conjunction with other injuries affecting the bones, ligaments, and cartilage of the knee. Sprains are divided into three categories based on severity. Grade 1 sprains involve mildly damaged ligaments that are still able to stabilize the knee joint; Grade 2 sprains involve ligaments that have been stretched so far that they are loose; and Grade 3 sprains involve ligaments that have been broken into two separate pieces, leading to total joint instability. Grade 2 sprains also are called partial tears, and Grade 3 sprains also are called complete tears. The majority of posterior cruciate ligament tears are partial tears, which can usually heal on their own. Most people with this type of injury eventually are able to resume normal activity without knee stability issues. In cases with combined injuries, surgery may be recommended. However, non-surgical treatment is usually effective and may involve resting, icing, applying compression devices, and completing a physical therapy program to restore function to the knee and strengthen the muscles that support it.