MCL Injuries | Connor Ziegler, M.D.

MCL Injuries and Treatment

What is the medial collateral ligament (MCL)?
The medial collateral ligament (MCL) extends from the the femur (thigh bone) to the tibia (shin bone) and is on the inside (medial) of the knee joint. There are three main anatomic structures in the medial side of the knee, with the superficial medial collateral ligament (sMCL) being the largest and strongest. The other main structures are the posterior oblique and deep medial collateral ligaments. An MCL injury/tear involves disruption of collagen fibers that comprise the MCL.

What causes an MCL injury?
A large number of isolated medial ligament injuries are due to sporting injuries. An MCL injury can occur through stress against the outside (lateral) aspect of the knee that stretches or tears the inside (medial) knee structures. This injury can be caused through either contact or non-contact. MCL injury can happen from clipping in football, falling down towards the inside of one’s knee, skiing, or other sports injuries causing a blow to the lateral knee stressing the medial side of the knee.

Skiing is one of the more common ways that an MCL tear happens. In fact, it is by far the most common knee ligament injury that occurs with skiing. This is because when one collapses down to the inside of their knee either with a fall or while slipping on an icier portion of the terrain, it puts extra stress on the inside of their knee. MCL tears often occur with ACL tears in skiers also.

What are MCL Tear Symptoms?

Pain directly over the ligament
Swelling and inflammation over the inside (medial) part of the knee
Severe cases patients will feel their knee “give out”, or buckle

It is important to make sure that you truly only have an MCL injury as part of the injury diagnosis. If one does have other things going on with the knee, especially an ACL tear or a meniscus tear, these have to be assessed. When one does have a diagnosis of an isolated MCL tear, one should work on icing the area to try to minimize swelling, use crutches as needed until one can walk without a limp, and avoid any side-to-side activities which could cause the MCL to heal in an elongated position. Dr. Ziegler will perform an examination, take x-rays and, in some cases, get an MRI to evaluate the MCL area to determine the extent of injury. An MRI shows the ligaments and muscles in addition to the bones, and it is very useful when determining if the injury is a partial or complete MCL tear along with determining if any other medial knee structures are torn.

How does one assess an MCL tear on MRI?
An MRI tear on MRI is best assessed on the coronal view. In these circumstances, we like to assess the 2 main portions of the MCL, which are the meniscofemoral and meniscotibial portions. The meniscofemoral portion goes from the meniscus up to the femur, whereas the meniscotibial portion goes from the meniscus down to the tibia. Most MCL tears are meniscofemoral-based and these have a fairly good blood supply and more underlying stem cells to allow it to heal. As long as it is not completely torn off the femur with the posterior oblique ligament and deep MCL, there is a good chance that these MCL tears will heal. Meniscotibial-based MCL tears can also heal. However, when they are torn off their distal attachment and retracted proximally, they can become entrapped in the hamstring tendons and have a low likelihood of healing back. In these circumstances, there is a much lower chance of these healing, but trying a rehabilitation program to allow the knee to have less chance of getting stiff after surgery may be indicated and there are some instances where these could potentially heal.

How does one test for an MCL injury?
Testing for an MCL injury involves both palpation and stressing to see if the ligament is torn. Palpation over the inside of the knee where the MCL courses may reveal pain, swelling, or thickness in the region of an MCL tear. Stressing the knee involves holding the thigh straight while pushing the leg towards the outside, which we call valgus stress. Ideally, one would put the examiner’s fingers directly over the joint line to assess if there is any gapping at the joint line to determine the grade of the MCL tear. Grade 1 partial MCL tears generally just have some mild tearing within the MCL and it does not gap at the joint line. Grade 2 partial tears do have some gapping, but there is an endpoint, whereas a complete grade 3 tear has no feeling of an endpoint at the joint line and is unstable. In all circumstances, one should always compare the amount of gapping to the normal contralateral knee when examining for an MCL tear to determine the “side-to-side” differences of gapping at the medial joint line.

MCL Injury Grading
The grade of the medial ligament injury is based upon the amount of tearing present.

Grade I Injury: occurs when there is just slight tearing and no significant gapping on exam
Grade II Injury: occurs if there is gapping present but an end point to valgus stressing at 30° of knee flexion.
Grade III Injury: occurs when there is a complete ligament tear of the medial side of the knee and stressing causes the lack of an endpoint. In chronic injury cases, a medial knee reconstruction will often be needed.

In general, most acute Grade I and II injuries will heal with a well supervised rehabilitation program. While the majority of isolated grade III medial knee injuries will heal, there are still some that do not heal. These injuries must be followed closely to be certain the patient does not have any problems with residual instability. In addition, it is well recognized having any “looseness” of the medial knee structures can cause an ACL graft to fail. Thus, when there is a combined medial knee injury and ACL injury, it is important to verify that the MCL injury heals completely prior to the ACL reconstruction or it should be concurrently repaired or reconstructed. In the case of very severe combined knee ligament injuries, especially with a concurrent PCL tear, the medial knee injury should undergo a repair, augmentation repair, or a complete medial knee reconstruction.

Will an MCL injury heal itself?
Many MCL injuries do have the ability to heal. This is especially true if the MCL is the only ligament torn around the knee. Partial MCL tears almost always heal, while complete MCL tears often heal. High grade MCL tears are less likely to heal when they occur with other ligament injuries in the knee, especially the PCL. In addition, MCL tears that completely tear off the femur and/or tear off the distal tibia attachment, and the knee gaps open in full extension with valgus stress, are the main types of MCL tears that do not heal.

Partial MCL tears should go through a program of icing, crutches as needed, and consistent use of a stationary bike to emphasize quadriceps reactivation, edema control, knee range of motion and encourage healing. Early knee motion, through use of a stationary bike, is very beneficial to help the healing MCL collagen fibers line up correctly and thicken so that they heal well. The more a patient uses a stationary bike with an MCL injury, as long as it does not cause any significant pain or swelling at the knee, the faster the MCL tear tends to heal. Even MCL tears that have a low likelihood of healing can benefit from having the knee quiet down and having a less chance of becoming stiff with a surgical reconstruction or repair with this program. MCL tears can hurt for several months while the healing and repeated stretching could cause some localized irritation of the healing tissues. For grade 2 and 3 injuries, the use of a hinged MCL protective knee brace is also commonly recommended in the acute situation when the knee is significantly unstable. Thus, we recommend the patient be fitted by one of our brace specialists. They will properly fit the MCL brace, which is durable enough for desired activity levels. The purpose of the brace is to help prevent the MCL from healing in an elongated position, which can lead to difficulty with side-to-side activities or planting on the affected knee and twisting towards the inside.

What is MCL Injury Recovery Time?
For isolated acute MCL injuries treated with a dedicated stationary biking progeam, most athletes can return to sports by multiplying the grade of the injury by two (in weeks) as a general time frame. Thus, a grade I acute MCL injury usually needs 2 weeks to heal, while a grade II injury takes 4 weeks to heal and a grade III isolated complete MCL injury typically takes 6 weeks of properly guided rehabilitation to have the injury heal completely.

When can an MCL tear be repaired?
There are many factors which need to be reviewed to decide when an MCL should be repaired versus reconstructed. A repair means reattaching the native MCL tissue, while reconstruction means using another ligament (typically hamstrings) to make a new MCL. If there is any significant stretch injury to the MCL, then a repair has a lower likelihood of healing. MCL tears off the tibia with little retraction may be the best indication for repair, especially if they are performed concurrent with an ACL reconstruction. In general, the results in the literature are more successful for reconstructions over repairs, so looking at having a repair done has to be carefully assessed to make sure that there is the best chance for healing.

Does an MCL tear hurt?
As with all injuries around the knee, there are wide varieties of types of MCL tears. A lot of the pain associated with a ligament tear is because of bleeding and swelling from the injury. Therefore, some minor MCL sprains may not hurt very much, unless one is shuffling side-to-side, whereas most complete tears will hurt, especially if one pushes down on the MCL in the area where it has been injured. People who have had a previous MCL tear may have had it heal a little bit loose and a new injury may be concerning for an MCL tear, when in fact it is an old injury that just healed a little bit loose. In these instances, we would expect that one would not have much pain in the region of the MCL.

What does it mean when one feels a pop with an MCL injury?
MCL tears in general do not cause a pop by themselves when they do tear. When one does feel a pop, one has to be concerned that it is a compression of the outside of the knee due to the opening on the inside causing a bone bruise in the lateral compartment. Bone bruises have been reported to be present about 50% of the time with a complete MCL tear. Bone bruises by themselves may or may not be a problem, depending upon whether the lateral meniscus is injured and the cartilage over the bone bruise has been damaged. A pop at the time of injury could also occur in the setting of an ACL tear in conjunction with the MCL tear. An MRI may be indicated in these circumstances where one has swelling within the knee with an MCL tear.

Which is the worst injury: MCL or ACL?
Almost all the time, an ACL tear is a worse injury than an MCL tear. This is because an ACL tear occurs inside the joint, where there is a very poor healing environment, whereas the MCL tear has a good blood supply around it and has an excellent chance of healing most of the time.

How does one treat an MCL tear in a hockey goalie?
Treatment of an MCL tear in a hockey goalie can be complicated because butterfly goalies are extremely MCL dependent. Therefore, allowing the MCL to heal prior to returning back to competition can be very important because if one returns back too soon before the MCL is healed adequately, the MCL could heal in a stretched-out position, which could affect one’s function. Therefore, wearing a brace, working on a stationary bike as often as possible, and focusing on straight-ahead activities until it completely heals before one does side-to-side or butterfly goalie drills would be indicated. In some instances, the scar tissue from an MCL tear can be limiting with one going down into a butterfly position, even when the MCL tears heal completely. In these circumstances, assessment by a physician to determine if a one-time intraarticular steroid injection may be indicated is a possibility. Also, once the MCL tear has completely healed, the use of anti-inflammatory medications as a trial for determining if pain relief may also be indicated.

When can I drive after an MCL tear?
The ability to drive after an MCL tear depends on the grade of the tear (grade 1, 2, or 3) and how one’s knee has responded to the physical therapy regimen. It is very important to have a normal brake/reaction time prior to returning back to driving. If it is one’s right knee, it could take 4-6 weeks for a complete MCL tear to heal sufficiently to be able to drive safely. With the left knee, as long as one does not have a clutch, once one can safely bend their knee in the car, they are not on any narcotic medications, and their right knee can function safely, it would probably be safe to drive with minimal risk. Always remember, you are not the only motorist on the road and need to consider the safety of others.

When can one swim after an MCL tear?
Once pain and swelling at the knee are controlled, one can get into a pool and use a pool buoy between their knees to work on upper extremity swimming. With grade 1 MCL tears, swimming should be possible within 2-3 weeks after injury for most people. For a grade 2 MCL tear, one would want to make the sure the MCL has healed sufficiently before starting any significant kicking and avoiding the breast stroke or flip-turns at the end of the pool to ensure that the MCL does not stretch out. For those with a grade 3 MCL tear, one should certainly make sure that the MCL has healed completely before they start any significant kicking in the pool, especially with the breaststroke, and avoid any flip turns at the end of the pool where they could stress their MCL. This could take anywhere from 6-8 weeks and should be assessed concurrent with your athletic trainer or physician to ensure that the MCL has healed sufficiently before starting this activity.

Why does an MCL injury hurt years later?
One of the most common reasons that MCL tears can hurt years later is because with a significant MCL injury, bone may actually form in the region of the tear rather than healing collagen fibers. This heterotopic ossification is called Pelligrini-Stieda disease. It may often show up years later on x-rays for somebody that had an MCL tear in the past. For those people who do have a lot of bone present, it can interfere with the collagen fibers from sliding from front to back as the knee bends, and this may cause some occasional irritation of this tissue. In addition, some people may have their MCL tear heal very thick and the increased thickness and scarring can be irritated if one does overdue it with long hikes or long runs even if one had an MCL tear, happen years previously. Surgery to treat this type of pathology is very rare and may only be indicated in people who have a lot of heterotopic ossification present that is causing their pain.

What does one do with a chronic MCL tear?
Patients who have a chronic MCL tear and who have instability need a complete workup to verify that the MCL tear is causing the problem and also to look at other associated body habitus issues which can affect the healing of the MCL tear. In general, chronic MCL tears in people who are knock-kneed have a much higher risk of causing symptoms and also having the surgery not work because of the extra stress placed on the inside of the knee when one is knock-kneed (valgus alignment). Therefore, long leg x-rays to look at one’s lower extremity alignment would be indicated in chronic MCL tears to determine if a surgery to take you out of the valgus alignment (a distal femoral osteotomy) would be indicated concurrent with an MCL reconstruction. In addition, it is important to determine objectively the amount of gapping that one with the use of bilateral valgus stress x-rays. Physician’s fingers are notorious for either underestimating or downplaying the amount of gapping that may occur, so confirming the amount of gapping objectively with the stress x-rays is one way to determine if the patient is having their symptoms from a complete MCL tear that has healed in an elongated position.

What does one do with an MCL tear after a total knee replacement?
MCL tears after total knee replacements are notorious for being difficult to heal. These can occur from releases during surgery, which are required to be able to insert the prosthesis, or they can occur because of an injury after the knee replacement. Surgery to treat these complete MCL tears can be difficult because they require reconstruction and the blood supply is not as good in these patients who have had knee replacements and these patients are generally older. Therefore, in many patients, the use of an MCL brace for activities may be indicated rather than a big surgical reconstruction. In those patients who do require surgery, a careful assessment to their overall health, which includes whether they use tobacco products, if they have diabetes, and other medical issues, is necessary to determine the ability of a reconstruction to heal for them.