Torn ligaments in the knee are common sports injuries that are painful and often debilitating. Four ligaments support the knee joint, and these can stretch or tear due to strikes, forces, and abnormal movements.
Tears are the most serious injuries to knee ligaments, and often require surgery followed by physical therapy, rehabilitation, and rest. Being smart about injury prevention in sports can prevent a lot of discomfort and downtime.
Learning About Knee Ligaments
The knee is a large and complex joint, made up of bones, muscles, cartilage, tendons, and ligaments. There are four ligaments in the knee that connect the bones in the joint and provide stability:
- Anterior cruciate ligament (ACL). The ACL is one of two cruciate ligaments inside the knee joint that connect the tibia (lower leg) and femur (thighbone). It is at the front of the knee and limits how far forward the tibia can move.
- Posterior cruciate ligament (PCL). The PCL is the other cruciate ligament. It sits behind the ACL and crosses it like an X. It stops the knee joint from shifting too far back.
- Medial collateral ligament (MCL). The MCL is one of two collateral ligaments, which stabilize the sides of the knee. It links the femur and tibia on the inside of the knee.
- Lateral collateral ligament (LCL). The LCL is the other collateral ligament and is situated on the outside of the knee joint. Together, the MCL and LCL prevent the knee from moving too much from side to side.
The four ligaments all work together to keep the joint stable. They prevent it from moving in a direction or in a twisting motion that could be painful or damaging. They also keep the bones aligned properly, and also absorb shock during impacts.
How Do Knee Ligaments Get Injured?
Excessive force on the knee can injure the ligaments, spraining or tearing them. A sprain is a stretch that often heals with rest and time. A torn ligament is a more serious injury that often requires surgery to repair.
The ACL and MCL locations mean that they are more often injured during sports activities. Sports that require a lot of pivoting and changing direction—soccer, basketball, football—put the ACL at risk of injury. Strikes to the outside of the knee, which can occur in contact sports like football, can injure the MCL.
Blows to the front of the knee can lead to PCL injuries. This can happen in sports, but is also seen in car accidents. An MCL or ACL tear vs a PCL tear is more likely sports-related. LCL tears result from a blow to the inside of the joint. These injuries are much less common than damage to the other ligaments.