A collateral ligament tear is an injury to the ligaments on each side of your knee. Ligaments connect bone to bone. These particular structures are called the Medial Collateral Ligament (MCL) and the Lateral Collateral Ligament. The Medial Collateral Ligament is on the inside of your knee and connects the bottom of the thigh bone (femur) to the top of your shin bone (tibia). The Lateral Collateral Ligament is on the outside of your knee connecting the bottom of the femur to the other smaller bone in your lower leg, the fibula. The job of these ligaments is to withstand forces placed on your knee that are directed from the sides. Both the MCL and LCL can be overstretched or tear either partially or completely when a force is applied to knee greater than these ligaments are able to withstand.


There are different grades of a sprain of these ligaments. A Grade 1 sprain is not a tear but an overstretching of the ligament, causing mild injury. A Grade 2 sprain involves an overstretch of the ligament to the point that it is no longer able to provide stability in the knee. This is a greater injury than a Grade 1 sprain, but the ligament is still intact to some degree, but perhaps not completely. This is often referred to as a partial tear of the ligament. Grade 3 is the category of ligamentous injury that is considered a complete tear or rupture of the ligament and it is no longer able to provide any stability to the knee. Surgical intervention will most likely be necessary with a Grade 3 sprain.

Commonly, a sports-related injury to the knee will cause one of these ligaments to be overstretched or rupture. Athletes are more prone to collateral ligament tears since they are participating in contact sports such as football or soccer which involve a lot of side to side, pivoting motions involving rapidly changing direction. Direct blows to the knee may also place undue strain on these ligaments. Causes of collateral ligament tears include:

● Powerful impact that forces the knee either inward or outward
● Quickly changing direction while running with significant speed
● Unnatural twisting of the leg and knee joint
● Direct hit to the left or right side of the knee

With sports-related injuries to the knee, the Medial Collateral ligament is more commonly torn than the Lateral Collateral Ligament. Both collateral knee ligaments may be involved with an injury to either side of the knee, but there are far more cases of MCL tears.

Whenever a ligament in the knee begins to be overstretched or tear, there will be immediate pain. You may hear a ‘popping’ sound at the time of injury indicating that there is a possible tear to a ligament in the knee. Whichever side of the knee is painful helps to determine which of these ligaments may be injured. There are other symptoms that you may experience along with pain located on the left or right side of the knee that can help you to identify a collateral ligament tear. These symptoms include one or all of the following:

● Swelling of the knee
● A pink color, or redness and warmth of the knee
● Pain located on the left or right side of the knee
● A feeling of lack of stability and weak knees that cannot carry your normal weight
● Pain experienced when attempting to passively move the knee through its normal range of motion
An increased body temperature as the body attempts to stave off infection


If You Are Experiencing Symptoms, Schedule an Appointment Dr. Burke Orthopedics Immediately.

It is important to always protect your knees, especially when playing sports. Even if you are not an athlete, you should protect your knees from unexpected injury, which can lead to chronic knee pain. Patients can lower their risk of collateral ligament tears by:

Regularly stretching your knee in various forms and maintaining flexibility in the surrounding structures
Exercising the knee and building stronger muscle tissue
Strength training to not only strengthen the muscles surrounding the knee, but the ligaments as well, adapting them to be able to withstand greater forces
Wearing protective knee pads or other gear when playing sports.