MCL: Runner’s Sprain Defined, Causes, Treatment, and Prevention


MCL Runners’ Sprain

MCL (medial ligament) sprains or Medial Cartlidge Meniscus injuries are some of the most common yet least talked about knee injuries. The most common forms of sprains occur after a sudden twisting motion is applied to the outside of the knee joint. For runners, this type of sprain is most likely to occur when the foot is planted on the ground, such as during improper stretching, or during a slip on a slick stretch of pavement. It is important for runners to understand how to prevent sprains as these types of injuries can have you off your feet from weeks to months.


The medial collateral ligament is located on the inside of the knee, external to the knee joint, is one of the four major knee ligaments. This ligament is called the medial collateral ligament because of its location within the knee. The MCL is located slightly on the inside of the knee, or on the medial side of the knee. The medial ligament resembles a thin, flat band-aid strapped over top of the side of the knee. From the knee, the MCL is attached above the joint to the femur and below the Adductor tubercle to six inches from the beginning of the tibia.



It is responsible for stabilizing the knee and allowing it to rotate. This gives the human knee its incredible range of motion that allows us to do run marathons, break dance, and perform everyday tasks such as walking, bending, and twisting. It also prevents athletes from overextending their knees too far on their side. Without an MCL, the knee would be susceptible to damage from any lateral force acting upon it, such as a blow to the knee, or the force you experience when your knee hits the sidewalk during a fall on your morning run through the neighborhood.


To understand how the sprain happens, we first have to understand how a sprain occurs in the first place. Sprains occur when a ligament in the body is pushed past its normal range of motion. When a lateral force is applied to the knee, this creates something called a valgus force – a lateral force on the outside of the knee that creates stress inside the joint. This stress causes the fibers of the ligament to be stretched passed their usual spectrum of movement. Anyone who has twisted an ankle knows first hand how uncomfortable these injuries can be. The next step is inflammation of the ligament, which is the body’s first step in healing sprains.

Types of Medial Collateral Ligament Injuries

There are three main types of medial collateral ligament injuries, ranging from minimal ligament tearing to extensive damage to the MCL.

Grade 1  sprains refer to a medial collateral ligament that has been over-exerted, but not actually torn. A Grade 1 injury can occur when the knee is 30 degrees and an outward force is simultaneously applied to the lower portion of the leg. This causes stress on the ligament and therefore, causes a minor sprain. Athletes usually feel pain, although there is no joint laxity, or loose ligaments present. When a runner sustains a Grade 1 sprain, it means that less than 10% of the fibers in the medial collateral ligament have been torn. Swelling of the ligament not usually seen with Grade 1 sprains.

A Grade 2 sprain refers to a partially torn ligament. Severe pain and tenderness on the inside of the knee are present, along with moderate joint laxity. This means that while the joint laxity is considerably more significant than that of a Grade 1 sprain, the knee cannot be bent completely sideways or out of the socket. Mild swelling is likely to occur over the ligament.

A Grade 3 sprain is the most severe type of sprain and refers to a complete tearing of the Medial Collateral Ligament. Significant joint laxity is present in the knee and is accompanied by the instability of the knee joint. Patients who have sustained a Grade 3 sprain may report having “wobbly knees” due the torn medial collateral ligament begin unable to support the knee. Swelling will occur over top of the MCL but surprisingly, many patients report the pain of a Grade 3 MCL sprain is less severe than that of a Grade 2 sprain.



A longitudinal cohort study was performed by researchers at the United States Military Academy to determine the incidence rate of MCL sprains at the Academy. Students’ medical records were reviewed by an Orthopedic surgeon to determine whether or not a student athlete had sustained an MCL sprain. Over the course of the study, 128 cadets suffered MCL sprains. Of these 128 cadets, 114 were male, and only 14 were female. From this data, researchers concluded that male athletes were 44% more likely to sustain a medial collateral ligament sprain than were female athletes.

It’s no secret that sprains can put an end to your running career for a few weeks, but just how long can you expect to be hanging up for running shoes for? Athletes who sustained Grade 1 sprains spent an average of 13.5 days off the playing field, with athletes sustaining Grades 2 and 3 spending an average of 29 days off the playing field. Overall, this means that a medial collateral ligament sprain could have on a running hiatus for an average of 22 days.

Although sprains are among the most common forms of knee injuries, the true rate of incidence is difficult to pinpoint as the vast majority of MCL sprains are never reported to physicians. Medical journals reports conclude the older adults are more likely than younger adults or adolescents to sustain  sprain due to a gradual decrease in ligament elasticity brought on as a by-product of the natural aging process. As elasticity in the ligament declines, joint laxity becomes increasingly more likely, causing instability of the joint. Athletes are most likely to incur sprain between the ages of 20 to 35.



Medial Collateral Ligament sprains are most likely to occur in contact and high intensity sports such as football, soccer, basketball, downhill skiing, volleyball, gymnastics, and of course running. As previously discussed in this article, medial collateral ligament sprains cause instability in the knee and difficulty performing normal functions like walking and running. This is because the MCL prevents the tibia from traveling too far forward during motion and becoming disconnected from the rest of the knee joint. For runners, the most common causes  sprains are rapid stops where the foot is planted on the ground and then swiftly rotated. Runners who have large leg muscles between their quadriceps and hamstrings are also more likely to sustain an MCL sprain due to the force of the quadriceps over extending the medial collateral ligament and leading to injury over time.

Like those with large quadriceps, runners who suffer from Genu recurvatum, a genetic condition causing a natural over extension of the knees are also at risk for sustaining an MCL sprain over time due to the added stress placed on the joints. To prevent sprains, runners should also pay attention to the position there are in when sitting down. If you sit with your knees pointed inward to touch each other, it is a good idea to adopt a different sitting posture as this position can add strain to your MCL over the course of your life. Sitting in this position can cause the Gluteus maximus, which this main external rotator muscle for the knees to cause the knees to rotate inward over time. Runners who are naturally bow-legged may also be more likely to develop an MCL injury due once again to added strain on the ligament and joint within the knee. Much less frequently,  sprains can also be sustained during traumatic incidents in which the knee is forced sideways.


Individuals who engage in high-risk sports, including those that involve sudden stops accompanied by a violent change in direction or shifting of body weight are at risk for developing a medial collateral ligament tear or sprain. Being overweight can also put you at risk for developing an sprain due to the added force applied to the medial collateral ligament. In addition to participating in the types of activities mentioned above, excess weight can over time cause the medical collateral ligament to partially give way, MCL sprains or in extreme cases, complete tearing of the ligament. When we walk or run, a force anywhere between 3 to 6 times your body weight is applied to your knees. This means that for every 10 pounds of additional body weight, an additional 30 to 60 pounds of force is applied to the joints and ligaments of your knees.

Data compiled from the National Health and Nutrition Examination Survey has shown that overweight women are up to 4 times more likely to sustain MCL injuries, while overweight men can be up to 5 times more likely to sustain an injury. Losing as few as 10 pounds can significantly reduce your likelihood of sustaining an MCL sprain. While running is a great way to reduce your waistline and set you up for a long and healthy life, overweight runners should take extra precautions such as wearing a knee brace and avoiding uneven terrain with a lot of loose gravel or dirt to prevent pulling on the knee due to slips and falls. Elderly runners should also take these precautions to avoid strain on the knee due to their decrease in elasticity. Even if you are young and in prime physical shape, all runners should take note of any possible risks associated with their running terrain and take the necessary precautions to prevent MCL sprains and other injuries associated with slips and falls as these injuries can be debilitating.

Signs and Symptoms

Now that you have some in-depth knowledge of the anatomy of the knee and medial collateral ligament and the underlying causes of injury, we can now learn about the signs and symptoms of MCL injuries. Symptoms of medial collateral ligament sprains vary based on the grade of MCL injury sustained. Athletes with Grade 1 MCL sprains report mild symptoms such as pressure and tenderness on the inside of the knee above the MCL. If you sustain a Grade 1 MCL injury, you can expect to be back out on the running trails in only 2 to 4 weeks. Symptoms of a Grade 2 MCL sprain are more severe and runners with these types of injuries usually report significant pain and swelling of the MCL. Grade 2 MCL injuries will have you off the pavement for anywhere from 4 to 6 weeks as sprains of this severity can cause substantial knee instability. Patients also experience physical symptoms such as difficulty performing twisting motions, walking, and keeping their balance. Finally, symptoms of the most debilitating form of MCL injuries, Grade 3 sprains include intense pain and swelling of the medial collateral ligament, sometimes causing immobilization of the knee. Patients suffering from Grade 3 MCL injuries also run the risk of their affected knees “giving out” under the strain of the pressure exerted on the torn ligament. A Grade 3 medial collateral ligament injury will have you off the road or trail for anywhere North of 6 weeks.


Biomechanics of Injuries

The science behind the way our bodies move is rather fascinating, yet is something most runners simply take for granted. In cadaver models, the strain causing an MCL tear started to occur when the knee was overextended by just 10.2 millimeters. The sprain was found to originate near at the spot on the knee joint where the medial collateral ligament is attached to the femur above. This finding suggests that the femur is the most common spot for an MCL sprain is at the femoral insertion of the knee. Surgeons have also found that the tibial attachment of the MCL is also a common location of sprain for the knee. The femoral insertion and tibia attachment are also the most common site of natural MCL wear and tear, which is why it is so important for runners to take extra precautions to prevent strain on the knee. By working to prevent MCL injuries, you are ensuring that you will be able to continue to enjoy running well into your golden years. If MCL tears are not treated immediately, further displacement of the ligament and knee joint will occur, leading to more severe injuries, which can in extreme cases, will not only have you off the trails but off your feet entirely.

All of this information may lead you to believe it is only a matter of time before an MCL injury will have you putting an early end to your running career. Research shows that despite the seemingly dubious evidence, keeping the medial collateral ligament mobile may be one of the most important things you can do to protect yourself from these injuries. Lack of movement of the MCL can cause degradation of collagen fibers inside the knee, reabsorption of bone at ligament insertion sites leading to bone loss, and a decline of the structural properties of the knee and medial collateral ligament itself. This information can arm you with the knowledge necessary to seek appropriate treatment for your MCL injury. Biomechanics experts claim that controlled movements such as physiotherapy treatments are the most effective non-operative remedies for MCL tears. Runners who seek intervention at an early stage in their injuries are most likely to experience success with non-operative therapies like physiotherapy. The positive news in all of this is that MCL injuries usually exhibit expectational healing capacity. However, biomechanics shows us that once injured, the MCL does not return to its post-injury functionality. While this probably will not spell to your weekend runs, but it will affect the amount of physical exertion your joints will be able to handle.



To diagnose an MCL injury, your doctor will lay you down on the examination and have you extend both legs. Your doctor will then have you bend the affected knee approximately 30 degrees in order to isolate your medial collateral ligament. A light valgus force will be applied to the area to test for a possible MCL injury. To fully diagnose an MCL injury, the soft tissue around the knee needs to be examined as well. To do this, the effected knee is fully extended and a gentle valgus force is repeated on the knee. During the examination of the knee, you doctor will also ask you whether you have experienced any pain, swelling, or a popping sensation in the knee. You may also be asked whether you have noticed any deformities of the knee after sustaining the injury.

If you have sustained a Grade 2 or 3 MCL injury and experience swelling, the location of the swelling can serve as a clue to the type of MCL injury you have. Isolated MCL tears will exhibit localized swelling at the site of injury. The site of swelling accurately indicates the site of injury up to 76% of the time. While rare, MCL injuries that are combined with ACL or PCL injuries present swelling combined with haemarthrosis. Hemarthrosis refers to bleeding in between joints.

If you suspect you have injured your MCL, it is very important to get to your doctor as soon as the injury occurs. MCL injuries are far easier to diagnose early, as the muscle spasms have not yet had time to develop. Depending on the grade of injury you have, waiting just a few days can make your injury drastically harder to diagnose.

Other Ways to Diagnose

If a severe MCL tear is suspected, your physician may opt for and MRI or other radiographs in order to avoid the strain placed on the medial collateral ligament during traditional exams. For adolescent runners, X-rays are used to diagnose MCL tears to rule out any possible physeal plate injuries, which are common in child athletes. There are other benefits to having your MCL sprain diagnosed with an MRI that you should be aware of.  MRI stands for Magnetic Resonance Imaging and uses powerful magnets and radio waves to show doctors detailed images of body tissues. The Hydrogen atoms in your body serve as tiny magnets that react to the powerful magnets in the MRI machine. These magnets cause the Hydrogen atoms in the affected area to line up and produce rotating magnetic fields that the MRI scanner then picks up. These tiny magnetic fields are used to create an image which is then sent to a radiologist to be read. MRI images can show doctors detailed representations of the tissues that make up your medial collateral ligament, meaning MRI imaging allows doctors to pinpoint the exact location in the MCL that your injury occurred. Knowing the exact location of your injury is the single best predictor of how well your MCL sprain will heal, even with the most serious kind of MCL sprains, and MCL injuries combined with ACL sprains. Although MCL sprains can have you off your feet for weeks to months, having it diagnosed properly and effectively will drastically improve your chances of a smooth recovery.


When to See Your Doctor: 

You should see your doctor as soon as you experience any unusual swelling or tenderness on the inside of your knee, or you experience pain. As stated above, having an MCL tear diagnosed early could mean the difference between weeks of crutches and bedrest and lacing up your runners and getting back out on the trails. More serious MCL sprains such as Grades 2 and 3 sprains are often accompanied by knee instability, so if you are having trouble keeping your balance, you feel your knees wobbling underneath your weight, you should see your doctor immediately.



Non-Surgical Intervention

Most likely, your MCL injury will be treated without surgical intervention. Most sports injuries and sprains are treated by a sports medicine physician or a physiotherapist. Your therapist will put you through a series of protected range of motion exercises and strength training exercises. Regardless of the grade of your MCL injury, it is important not to over exert your injury. This means taking it easy and not over doing things. Resting your tissues is arguably the most important thing you can do yourself to heal your MCL injuries. Your ligaments are delicate tissues that need time to heal and rebuild their strength. Doctors also recommend elevating your injuries to promoting healing. Working with your physician or physiotherapist and obeying their orders will have you lacing up or running shoes and heading back out on the road in no time.



A lesser known treatment for MCL sprains is cryotherapy. Cryotherapy involves localized freezing of a nerve to temporarily deaden it and relieve pain. A doctor will insert a probe into the nerve closest to your medial collateral nerve to temporarily freeze it. This freezing inactivates the part of the nerve responsible for sending pain impulses to your brain, therefore temporarily halting the pain. Cryotherapy can even be used to treat more severe conditions such as certain forms of cancer. While effective, cryotherapy does have certain side effects that you should be aware of. Side effects of cryotherapy can include numbness, prickling feelings, nerve irritation in the affected area. These side effects are usually temporary and cryotherapy is generally regarded as a safe method of treatment for MCL sprains.

Player recieving cryotherapy on the sideolines of a game

Compression Therapy

Like many sports injuries, compression of the tissues is used as a treatment for MCL sprains. The goal of compression therapy is to reduce swelling of affected tissues by promoting increased blood flow to the area. Sports compression garments can be purchased at any pharmacy or sports supply store. Applying a cold compress to your MCL injury is also recommended to reduce redness and swelling in the area. Ice should be applied to the injury in 15 minute intervals every two hours for the first few days after sustaining the injury. You can reduce this to every 3 hours over the next few days as the swelling goes down.


Surgical Intervention

If left untreated, minor MCL injuries may become increasingly more severe over time and eventually require surgery to correct the outstretched medial collateral ligament. Surgical intervention is usually only recommending when an MCL sprain has progressed to a complete tearing of the ligament that will not heal on its own. Surgery may also be suggested when an MCL injury is accompanied by a tibia fracture. You can expect your surgery to take place 7 to 10 days immediately following the diagnosis of your MCL injury. Your doctor will also recommend an MRI in order to pinpoint the exact side of injury to assist in surgical planning. During surgery, your surgeon will secure your medial collateral ligament back into its insertion points in the knee using staples or small suture anchors since the MCL is not able to grow back into place naturally. After surgery, it is important to rest the affected leg until the MCL is healed enough to start regaining strength. At this point, you can work with a physiotherapist to build up enough strength to begin carrying your body weight on your affected knee. The total recovery time of an MCL surgery is typically a few months.


How to Heal and Prevent Injuries at Home

While it is paramount to visit a doctor as soon as you think you have incurred an MCL injury, there are things you can do at home to heal minor MCL injuries yourself. It is important to avoid activities that cause pain to your injury. To rebuild your strength, practice walking around your home without the aid of crutches or other supports as your pain allows. Apply an ice compound to your injury after walking in order to reduce further swelling. Keep this up for about a week.

After the first week following your injury, you should continue to limit your participation in painful activities. As you start to regain your strength you can begin to resume light jogging or short runs around your neighborhood. Avoid trails with loose gravel that could cause you to fall and sustain an additional injury. After light exercise, apply a cool compress to the area.

Two weeks following your injury, you can begin to slowly return to your usually running routine, keeping in mind, however, to pay attention to your body and rest whenever necessary. Keep up the cool compresses and remember to stretch daily.

Three weeks after your injury, you can return to your favorite routes and hit the trails with your friends. If you are training for an intense run such as a marathon, remember to take it easy with your training until receiving the go ahead from you doctor.

Stretches for Treating Injuries

Stretching can be an effective way to rebuild your strength following an MCL injury. The following is a list of the most effective MCL stretches:

  • Knee Extensions
  • Knee Flexions
  • Half Squats
  • Step Ups
  • Calf Raises
  • Bridges
  • Leg Presses

You should aim for between 10 to 20 reps of each exercise and remember to pay attention to what your body is telling you. You can also use exercise equipment like cycling machines, stepping machines, and treadmills to regain your MCL strength by performing light exercise.

Wrapping Up

In order to prevent MCL injuries in the first place by remember to stretch every time you run. You can also buy compression garments and sports tape that can be used to keep your knees in place in the event of a fall to prevent injury. Avoiding sudden movements and changes of direction are also important to prevent tearing of the medial collateral ligament. Remember to go slow when running on uneven terrain. If you are elderly or otherwise prone to MCL sprains, remember to avoid running in the rain or on slippery surfaces to prevent falls. Even though MCL sprains are fairly common, following your doctor’s orders and the advice outlined in this article will help you to effectively prevent and treat your injuries and run safely.