Knee Ligament Injuries

While ACL injuries are very common, additional injuries in the knee can include the medial collateral ligament (MCL), the lateral collateral ligament (LCL) and the posterior cruciate ligament (PCL).

MCL Injuries

The MCL prevents the inside of the knee from opening up or buckling during movement. An MCL tear can occur as an isolated injury or it can be associated with other knee injuries, in particular tears of the ACL and medial meniscus.

The most common symptoms are:

Hearing a popping upon getting the injury.
Pain near the inside area of the knee
Swelling of the knee joint
Not able to put weight on the knee when applying pressure to the area

Most MCL tears heal on their own, without the need for surgery.

The severity of the injury is graded from I (minor) to III (complete tear). To help you determine which type of MCL injury you have, here is a description of each degree of MCL sprains:

Grade 1 MCL Injury: Refers to a strained, but not torn, ligament. It is the least severe injury out of all three grades.
Grade 2 MCL Injury: A ligament that is slightly torn, causing some instability and discomfort in the knee.
Grade 3 MCL Injury: The most severe, is a ligament that has completely torn.

Treating MCL Tears

Most MCL tears heal on their own, without the need for surgery. In higher-grade injuries, a brace is often prescribed to protect the ligament while it heals. Grade I and grade II injuries usually heal within 4-6 weeks, though full recovery may take longer.

Surgery to repair the MCL may be needed for some grade III injuries or less severe but chronic MCL injuries that have not healed appropriately. Here are the three most common treatments for MCL injuries:

Immediate treatment: Applying treatment immediately to the affected area is crucial to a quicker recovery time for all three degrees of MCL sprains, including applying ice to the injured area to reduce the swelling, elevating your knee to reduce swelling and using crutches to keep weight off your knee.
Rehabilitation: The goal is to gradually regain your strength in the impacted knee to prevent the injury from recurring. Your surgeon may recommend physical therapy, wearing a protective knee brace and limiting certain activities.
Surgery: Rarely, surgery is necessary, especially when the ligament is torn beyond the point of self-repair or when the MCL sprain has caused the injury of other ligaments.

LCL / PLC Injuries

The lateral collateral ligament (LCL) is on the outside of the knee and connects the thigh bone to the one of the shin bones. It is part of a larger group of structures referred to as the posterolateral corner (PLC).

The LCL and PLC provide stability to the outside of the and for the rotation of the knee.

What are the causes and symptoms of LCL and PLC injuries?

The LCL and PLC are typically injured from an impact to the inside of the knee or from tears of other knee ligaments.

The most common symptom following an injury to the LCL and PLC is pain over the outside of the knee. Swelling, decreased motion, instability and difficulty placing weight on the knee are also common with this injury

How are LCL and PLC tears treated?

Partial tears of the LCL and PLC structures can be treated without surgery, but complete tears usually require surgical treatment.

Surgical repair involves either sewing the ligaments back together or reconstructing them using a tendon graft. If other ligaments are also injured in the knee (ACL, MCL, or PCL), these can be surgically addressed during the same surgery.

PCL Injuries

The PCL, along with the ACL, is located in the center of the knee. Its primary function is to prevent the thinner shin bone (tibia) from moving backward away from the thigh bone (femur). It also plays a role in the side-to-side stability of the knee.

Causes and Symptoms of a PCL Injury

PCL injuries are less common than ACL injuries. The most common mechanism of injury involves a blow to the front shin bone when the knee is bent. PCL tears can occur as isolated injuries or can be associated with other knee injuries.

The symptoms of a PCL injury are usually less severe than those of an ACL tear. Mild swelling can occur and pain associated with a PCL injury is resolved within 2-4 weeks. However, a sense of instability may persist.

PCL Injury Treatments

Treatment for isolated PCL injuries initially focuses on rehabilitation and strengthening once any pain and swelling subside.

Partial tears of the PCL do not usually require surgical treatment, and even come isolated complete tears of the PCL do not always need surgical treatment.

If symptoms of instability persist after rehabilitation, surgical reconstruction of the PCL is recommended. PCL knee surgery involves completely removing the torn ligament and reconstructing the ligament using a minimally invasive surgical technique.

The new ligament is made using a tendon graft, usually through an allograft.