How many cruciate ligaments are there in the knee joint?

Three bones meet to form your knee joint: your thighbone (femur), shinbone (tibia), and kneecap (patella). Your kneecap sits in front of the joint to provide some protection. Bones are connected to other bones by ligaments. There are four primary ligaments in your knee; two collateral ligaments and two cruciate ligaments. They act like strong ropes to hold the bones together and keep your knee stable.

The cruciate ligaments cross each other to form an "X" with the anterior cruciate ligament (ACL) in front and the posterior cruciate ligament (PCL) in back. The cruciate ligaments control the back and forth motion of your knee.

Injury to the ACL are more common than injuries to the PCL. ACL injuries can happen several ways, including changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly and direct contact or collision, such as a football tackle.

Injured ligaments are considered 'sprains' and are graded on a severity scale from Grade 1, a mild sprain to Grade 3, a complete tear. Partial tears of the ACL are rare; most ACL injuries are complete or near complete tears.

Treatment for an ACL tear will vary depending upon the patient's individual needs. For example, a young athlete involved in agility sports will most likely require surgery to safely return to sports. The less active, usually older, individual may be able to return to a quieter lifestyle without surgery.