Knee pain is a common problem for runners, but often it is tricky to figure out what caused it. In this article, we’ll discuss the most common causes of knee pain in runners and how you can distinguish between them. We’ll also share the top three treatments that we find work best for dealing with each of these knee injuries. Remember, if you need more help with an injury, you're welcome to consult one of our physios online via video call.
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In this article:
We've also made a video about this:
Inner (medial) knee pain when running
Medial meniscus tear
The pain from a medial meniscus tear is usually felt on the inside of the knee, along the inner joint line. It can also be located a bit more to the inner front or inner back of the knee, depending on which part you injured. It is usually caused by a sudden twisting movement or deep kneeling. It is often accompanied by some swelling, and it may be difficult to fully bend or straighten your knee.
Meniscus injuries can feel very similar to bone bruising and medial collateral ligament tears, and these three injuries can often happen at the same time. Your physio or doctor can help you to distinguish between them.
I've also made a video where I discuss meniscus tears and their treatment in detail:
My top three treatment suggestions:
Let it settle - Allow your knee three to seven days to settle before you start any serious rehab exercises. You don't need complete rest, but limit how much time you spend on your feet (standing and walking) - if your knee hurts more in the afternoon or evening, it may be a sign that you're doing too much. Use ice and gentle movement (bending and straightening your leg) to help your knee calm down and the swelling to reduce.
Follow a progressive rehab plan that includes exercises that strengthen your glute and thigh muscles and balancing exercises to restore your control and position sense. These have to start in positions that don't place a lot of load through your injured knee and then slowly increase in intensity and complexity as your knee recovers.
Refrain from running until you have:
Regained full range of motion,
And full strength,
And good balance and control.
Medial collateral ligament (MCL) tear/strain
The medial collateral ligament runs over the inside of the knee. It resists forces that try to gap the inner part of your knee joint and stops your knee joint from bending outward too much. You usually strain or tear it through a sudden movement, often involving a twisting action, very similar to the type of movement that injures the medial meniscus. But you can also develop an overuse MCL injury if your knee turns in excessively when you run or walk. Tears can vary from a mild strain to a significant tear that may require you to wear a brace.
You usually feel a sudden sharp pain when you tear/strain your MCL. You may notice a bit of puffiness or swelling over the inner knee line, and you will be able to locate a painful area in the ligament when you press on it. Depending on the severity of the tear, you may not be able to fully bend or straighten your knee. MCL strains can often be misdiagnosed as meniscus injuries, but they can also occur together with a medial meniscus tear.
I've also made a video where I discuss MCL tears and their treatment in detail:
My top three treatment suggestions:
Avoid activities that strain the ligament. This advice applies to the early stage of rehab; by avoiding activities that make your knee move inward, you give the ligament a better opportunity to repair the injured area. Examples of activities to avoid include running, walking on uneven or soft ground, walking in unsupportive shoes, and dancing.
You may benefit from wearing a knee brace for a few weeks, but this will depend on the severity of your strain. If it is a minor strain, you may be OK if you're careful and just avoid certain movements. However, if you have a moderate to severe strain/tear or a job that forces you to move in ways that may strain your injured ligament, it is best to invest in a knee brace that limits the side-to-side movement in the knee as well as the last 30 degrees of knee extension (straightening your leg). This will allow the ligament to repair. Your physio or doctor will guide you with regards to this.
Rehab exercises tailored to your specific needs. It's good to work on general strength and control in your core and legs, but you may want to focus on specific areas, depending on what your physio thinks contributed to your MCL strain. For instance, weak glute muscles or poor ankle stability can cause your knee to turn in more when you run, increasing the strain on your MCL. Reduced proprioception (position sense) can also predispose you to this injury. Position sense can easily be retrained through balancing exercises.
Bone bruising (inner or outer knee)
Bone bruising is actually a common injury despite not being talked about that much. It can develop over time due to repetitive low impacts – for example in endurance running.
But it can also happen when a sudden movement squashes the bones that form the top (femur) and bottom (tibia) of your knee joint together. It is also common for the movements that injure the menisci or ligaments to cause bone bruising. Bone bruises can cause pain very similar to a meniscus tear or ligament strain.
Bone bruises can only be diagnosed via scans. They can take quite a long time to heal fully.
Here's a video with more detailed info and advice on bone bruising:
My top three treatment suggestions:
Reduce the load on the area that has the bone bruise. The extent of your injury will determine what you should do. For example, if your knee is very painful, you may have to use crutches for a while. If it's only a minor bone bruise, you may just have to avoid standing or walking for lengthy periods, or high-impact activities like jumping and running. Let pain be your guide - aim to cut out or reduce the intensity of all activities that cause pain during or after you've done them.
Keep your body strong. It's important to maintain your muscle strength and control while you wait for your bruised knee to recover. Choose exercises that don't place a lot of force through your knee, e.g. clams with resistance bands, knee extensions, or curl machines in they gym, or bridges with weights. Cycling or swimming are good options for cardiovascular fitness during this time.
Vitamins and minerals. You can help your bones recover by ensuring that they have all the vitamins and minerals they need. The main building block for bone is calcium (found in dairy products and other fortified products), but you can only absorb it if you have sufficient levels of vitamin D. Your doctor can test your vitamin D levels and suggest a supplement if needed.
Outside (lateral) knee pain in runners
Lateral meniscus tear
Lateral meniscus tears are much less common than medial meniscus tears. The pain from a lateral meniscus tear is usually felt on the outside of the knee, along the outer joint line. It can also be located a bit more to the outer front or outer back of the knee depending on what part you injured. They are traumatic injuries that usually happen suddenly, like when you stumble or twist an ankle. Here's our full article on lateral meniscus tears.
My top three treatment suggestions:
The treatment for lateral meniscus tears is exactly the same as for medial meniscus tears. You can find a detailed explanation above, but it consists of:
Relative rest to allow the injury to settle
A progressive rehab plan
Refrain from running until you have:
Regained full range of motion,
And full strength,
And good balance and control.
Lateral collateral ligament (LCL) strain/tear
Lateral collateral ligament tears are not common in runners, because it usually takes a lot of force to tear your LCL. It is a traumatic injury with a clear cause, e.g. falling hard in an awkward way or taking a direct blow to the knee. I'm not going to suggest treatment options for this, because it usually happens in combination with other, more serious injuries (like posterior cruciate ligament tears) that dictate what treatment should be followed.
IT band syndrome
IT band syndrome causes pain where the IT band crosses over the outside of the knee joint. It's an overuse injury. It may start as only a slight niggle or discomfort during a run or after a run. But the pain then increases if you continue to train without having fixed the problem.
We've done a detailed explanation of the causes and treatment of IT band syndrome. The main cause of IT band syndrome is thought to be linked to poor biomechanics (pelvis dropping, knee turning in, foot overpronating) when you run. There are several factors that can influence your biomechanics negatively, such as running on very tired legs, running on a cambered surface, having weak glutes, or poor ankle and foot strength and control.
I've also made a video where I discuss the causes, symptoms and treatment of IT band syndrome in detail:
My top three treatment suggestions:
Rest it - All the research projects that investigated how to successfully treat IT band syndrome with rehab exercises asked their participants to take a break from running for six weeks to allow the tissue to calm down. But some people may be able to continue running if they reduce their training load; we discuss how you can decide whether you are OK to run with IT band syndrome here.
Rehab - Depending on what caused your specific case of IT band syndrome, you may benefit from doing either IT band stretches, strength training exercises, control exercises, or a combination of these. This is why it is useful to have an assessment by a physio who can compile the most effective treatment plan for you.
Gradual return to running - Once your IT band has calmed down and you've restored the strength and control you need, you have to ease back into running gradually. The injured tissue won't yet have the capacity to cope with all the running you might want to do, and it is important to build this up slowly.
Front (anterior) knee pain from running
Patellofemoral pain syndrome (runner's knee)
Patellofemoral pain syndrome is an overuse injury affecting the underside of the kneecap. The most common causes of this include a sudden increase in running volume or running speed. But poor control and strength in the other muscles of your leg as well as your core may also play a role, as this can lead to greater forces working on the kneecap. Sometimes, non-running activities can be to blame, e.g. kneeling for a lengthy period in the garden or while tiling a floor, or doing lots of deep squats.
The pain is usually felt over the front of the knee, but it can also cause pain to the sides of the kneecap, above, or below it. Often, it's not possible to find the painful spot when you try and push on it. It tends to develop gradually and increase in intensity as you continue to train.
My top three treatment suggestions:
Reduce your pain by:
Avoiding aggravating activities
Trying different taping techniques
Include exercises that retrain the quadriceps muscles. It is important to start with these in positions that don't create large loads on the kneecap (avoiding deep knee flexion). It is also often better to start with isometric exercises and to avoid repetitive flexion and extension of the knee.
Running technique - If you tend to land with your foot far out in front of your body or run with a narrow gait, the research shows that making changes to your running technique may help to settle your patellofemoral pain.
Patellar tendonitis/tendinopathy
Your patellar tendon is the thick tendon that runs from the lower edge of the kneecap to your shin bone (tibia). Patellar tendonitis or tendinopathy is usually caused by overuse that sets in slowly during one very hard session or over several sessions (ramping training up too quickly or not allowing enough recovery), but it can sometimes develop after getting hit on the tendon. If you felt a sudden sharp pain when you injured your knee, it's more likely that you've sustained a tear.
You feel the pain from patellar tendonitis over the front of the knee, in the area just below the kneecap. There is usually a specific part of the tendon that feels painful to press on. It can easily be confused with fat pad impingement or patellofemoral pain syndrome. It tends to hurt when you do activities that use the quad muscles, e.g. jumping, running, or squatting. You may find that it feels OK or even better while you exercise, only for it to flare up worse the next day.
I've also made a video where I discuss the treatment of patellar tendonitis / tendinopathy in detail:
My top three treatment suggestions:
Relative rest - Tendons don't require complete rest to recover. They often do better if you remain active but just cut down or adjust the activities that really aggravate them. Analyse your sport and all your daily activities. How much, or for how long, or at what intensity can you continue to run without making your tendon pain worse in the 24 hours after the run? This may require you to do only easy, short runs, and less often than usual.
Strength training exercises - There is strong evidence to support the use of a progressive strength training programme as treatment for patellar tendonitis. There are two factors that such a programme should adhere to:
It should start at the correct intensity for your tendon's current capacity. Injured tendons lose some of their strength, and if the exercises are too intense, they can actually make the tendon more sensitive.
It should slowly be progressed until the exercises resemble the forces that your tendon will have to resist during your normal sport. This is important if you want to avoid reinjury.
Include exercises that retrain landing mechanics - The patellar tendon works much harder when you land (either from a jump or while running) than when you push off. It is important to retrain that action and ensure that the other parts of the body (kinetic chain) are all accepting their part of the load.
You can find a discussion of the other common treatments used for patellar tendonitis here.
Quadriceps tendonitis/tendinopathy
Your quadriceps tendon attaches your four quad muscles to the top of your kneecap. Like patellar tendonitis, quadriceps tendonitis is an overuse injury caused by an overload of activities that require the quadriceps muscles to work very hard eccentrically, e.g. heavy loaded deep squats, lots of jumping activities, or downhill running.
The pain is felt above the kneecap in the area of the quadriceps tendon. It is usually most painful in positions where the knee is loaded in a flexed position (deep knee bend), e.g. at the bottom of a squat.
My top three treatment suggestions:
The treatment for quadriceps tendonitis is exactly the same as you would do for patellar tendonitis so have a look at the advice listed above for the details but in summary, it consists of:
Relative rest
Strength training
Retraining biomechanics
Fat pad impingement
There's a fat pad just under the patellar tendon, in the area where the bottom of the thigh bone (femur) meets the top of the shin bone (tibia). The fat pad can get pinched between the kneecap and the thigh bone or between the shin bone and thigh bone. It is filled with nerve endings and can cause a lot of pain when pinched.
Fat pad impingement is often caused by uncontrolled hyper-extension of the knee or after a direct blow to the knee that causes it to swell. The pain is felt over the front of the knee, below the kneecap and can be mistaken for patellar tendinopathy or patellofemoral pain syndrome. When you press in the area, the pain is usually located next to or behind the tendon instead of on it. It is typically aggravated by activities that fully extend the knee, e.g. straight-leg raises or standing for long periods.
My top three treatment suggestions:
Exercises that improve the control around the knee, especially end range extension. Include exercises that work the hamstring eccentrically, as it is they that must slow the knee extension down and prevent hyper extension. Limit your exercises to the pain free range and it's usually best to avoid full extension to start with.
Consciously work on your movement patterns and habits. Incorporate this into your rehab but also your daily activities. Do you have a habit of locking your knees into hyper-extension when you stand for long periods? If so, adjust that position and teach yourself to stand in a more neutral position.
Taping the kneecap. If your kneecap is the culprit, you may benefit from applying different taping techniques that adjust its position slightly. However, in my experience the effect of this is rather short-lived, so don't view this as a long-term solution.
Referred pain from the hip
This may sound a bit bizarre, but it is possible that your knee pain is actually coming from your hip, even if you don't have any pain up there. This is why it is important that your physio doesn't just check your knee when you have knee pain. They should always include screening tests for the joint above (the hip) and the joint below (the ankle).
General knee pain after running
If your knees are feeling generally achy after runs and the discomfort lingers for a day or two, it may be that you’re overloading them. Rather than getting a specific injury, the joint and some of the structures in and around it are becoming irritated because they are either being asked to work harder than what they currently have the strength for, or they are not being given enough time to recover. If this continues for too long, it can eventually cause an injury.
My top three treatment suggestions:
Yes, training errors are often to blame for this, but there may be other things you need to look at as well:
Check that your running shoes are not too worn and that they provide enough support and cushioning.
Are your leg muscles strong enough? Your muscles are meant to absorb much of the impact when you run, and if they aren’t strong enough it can force your knee joints to take more strain than they should.
Review your training plan (not just running, but also strength training and other activities). Do you need to adjust it to allow more time for recovery? Are you ramping your training up too quickly?
How we can help
Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. But at Sports Injury Physio we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author
Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.
References
Brukner, P, et. al. Brukner & Khan's Clinical Sports Medicine. Vol 1: Injuries. (2017) McGraw-Hill Education. (Links to Amazon)
Louw, Maryke, and Clare Deary. "The biomechanical variables involved in the aetiology of iliotibial band syndrome in distance runners–A systematic review of the literature." Physical Therapy in Sport 15.1 (2014): 64-75.