The ABCs of ACL, LCL, MCL, and PCL Injuries
The knee is one of the human body’s largest joints and one of its strongest. The knee structure is quite complex, and the human body demands a lot from it daily. It is home to four major ligaments, the ACL, LCL, MCL, and PCL. Each of these ligaments is a strong, elasticized band of tissue that connects the thighbone to the two shin bones and provides the knee joint with stability for all of its activities. The knee simply wouldn’t be the powerhouse it is without the ACL, LCL, MCL, and PCL ligaments.
Of course, the knee’s structural complexity and the daily demands on it make its ligaments (as well as other knee structures) susceptible to injury and damage – especially for athletes of all ages and levels.
Below is a brief overview of each of the four major knee ligaments, their function, and the ways they can become injured:
The Cruciate Ligaments – ACL (Anterior Cruciate Ligament) & PCL (Posterior Cruciate Ligament)
The ACL is in the front center of the knee and controls the lower leg bone (tibia) from sliding forward on the thigh bone (femur) as well as controlling rotation or pivoting of the knee. ACL injury typically occurs during athletic participation when stopping, changing directions, jumping abruptly, or trauma from a blow to the knee when it is in a more extended position. A tear(sprain) of the ACL is one of the most common injuries especially in contact sports.
The PCL is located at the back of the knee and controls the tibia from sliding backwards on the femur. Injury to the PCL ligament most often occurs due to a sudden and direct blow, such as a tackle in football usually with the knee in a bent(flexed) position or by the knee hitting the dashboard as in an automobile accident. It is far less common to injure compared to the ACL.
The Collateral Ligaments – LCL (Lateral Collateral Ligament) & MCL (Medial Collateral Ligament)
The LCL is located on the outside(lateral) side of the knee and provides stability to the outer knee. The MCL is located on the inside(medial) side of the knee and provides stability to the inner knee. The LCL and the MCL are designed to withstand large loads placed on the knee. As such, they are commonly injured via a direct blow to the side of the knee, with injury to the MCL being most common.
Whenever an injury to the knee occurs, resulting in pain, swelling, instability, or disability, it is essential to schedule an appointment with a highly qualified and experienced orthopedic surgeon as soon as possible.
The Fellowship-trained orthopedic and sport medicine specialists at the Cedars-Sinai Kerlan-Jobe Institute are leaders in the diagnostic and surgical expertise of knee injuries. Whether by rehabilitation, regenerative treatment, reconstruction or replacement, we have expertly treated a wide range of knee conditions in elite athletes, weekend warriors, pediatric and adolescent athletes, as well as injured workers, active seniors, and everyone in between.
While a thorough history, physical examination and x-rays may be all that is needed for a definitive diagnosis, other diagnostic imaging studies such as MRI may also be required. Once a diagnosis is made, then the orthopedic surgeon will discuss a tailored treatment plan focused on your recovery goals.
Depending on the severity, some patients can recover from ACL, MCL, PCL, or LCL ligament injury with a rehabilitation program including physical therapy and bracing. However, ligament reconstruction or repair is often recommended for both athletes and non-athletes who wish to return to a more active lifestyle including sports or arduous work.