Key takeaways:
There are many reasons why your knee may hurt, including inflammation, injury, and arthritis.
A common cause of knee pain is overuse. Gentle exercise, stretching, and over-the-counter (OTC) medications can help relieve this type of pain.
In rare cases, knee pain can be a sign of a serious underlying illness, so you shouldn’t ignore it. A healthcare professional can help you figure out what’s causing your knee pain.
There are a lot of causes of knee pain. If you suffered a traumatic injury such as a fall, it might be pretty clear what’s causing your pain. If you haven’t had a specific injury, though, it can be a bit more challenging to figure out what’s causing your pain and how to treat it. Most causes of knee pain aren’t serious. However, in some cases knee pain can be a sign of other medical conditions.
Here’s a look at different types of knee pain and how to deal with them.
What are the causes of knee pain?
There are many different reasons why your knee may hurt, including injury, arthritis, and inflammation. Here are some common causes of constant aches and pains or discomfort in the knee.
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Osteoarthritis
Osteoarthritis is a condition where parts of the knee joint start to break down over time. First, the cartilage in the joint, which provides cushioning, begins to wear out. After this, changes to the bone, ligaments, and tendons occur.
Overuse of the knee is one factor that leads to arthritis. But other factors such as previous knee injuries or surgeries can also contribute. Symptoms of osteoarthritis are swelling, pain with activity, and joint stiffness that slowly worsen over time.
Patellofemoral pain syndrome
Patellofemoral pain syndrome causes pain in the front part of the knee with activity. It’s caused by overuse and misalignment of the patella (knee cap) and the tract it moves in when you move your knee joint. It’s more common in women and young adults.
Lack of activity
Sometimes, lack of activity can lead to knee pain. If you live a sedentary lifestyle, or if you have a period of decreased activity, several changes can happen that put you at risk for knee pain:
Decreased flexibility develops over time, which can lead to knee pain. Less flexible muscles and joints are more likely to get injured, which can lead to misalignment of joints.
Decreased strength can lead to misalignment of joints as well.
Weight gain — which often happens during less active periods — can put more stress on the knees.
Knee injuries
Knee injuries usually cause sudden knee pain that occurs with trauma or regular activity. Many knee injuries respond to simple measures like rest, ice, and physical therapy. Some of the more common knee injuries include:
Anterior cruciate ligament (ACL) tear: This injury usually happens from pivoting or landing badly from a jump. About half of ACL injuries come with damage to something else in the knee, like the meniscus or cartilage.
Meniscus tear: This injury often occurs from twisting at the knee or being tackled. But as the meniscus weakens with age, even an awkward twist getting up from a chair can tear it.
Collateral ligament injury: This usually comes from a force that pushes the knee sideways. A blow to the outside of the knee tends to injure the medial collateral ligament (MCL) — the ligament on the inner side of the knee.
Posterior collateral ligament (PCL) injury: This is typically from a blow to the front of your knee when it’s bent. Dashboard injuries in car crashes are a classic example.
Tendon tear: The quadriceps and patellar tendons can stretch or tear from falls, direct force to the front of the knee, or bad landings. This is more common in middle-aged people who run or jump.
Fracture: The kneecap is the bone most often broken around the knee, usually from high-energy trauma like a fall from a height or a car crash. Fractures of the upper part of your tibia and fibula can also involve the knee.
Bursitis
A bursa is a small sac of fluid in a joint that helps it move smoothly. Sometimes, these sacs can get inflamed and irritated, causing pain. This is called bursitis.
Bursitis can happen for a lot of reasons, such as kneeling for too long, overuse of the knee, or for no clear reason. Pain can be in different parts of the knee, because there are a few different bursae in the knee. In rare cases, bursitis can be caused by infections.
Usually, pain improves from treatment with rest and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.
Gout
Gout is a condition where tiny crystals develop in the knee, causing swelling and pain that can be severe. The crystals are made of a substance called uric acid, which builds up in the joints.
A gout attack can be treated with NSAIDs, colchicine, or prednisone, which are all anti-inflammatory medications. If you have multiple gout attacks, medications that lower uric acid in the body such as allopurinol can help prevent attacks.
Location of knee pain
Where your knee hurts can help narrow down what's wrong with it. Pain in a particular spot usually points to the structure sitting underneath it:
The kneecap joint in front
The ligaments and cartilage on either side
The tendons above and below
Here’s a table that can help you figure out why you have knee pain based on where it hurts.
Where it hurts | Common causes | Other clues |
|---|---|---|
Front (around or behind the kneecap) | • Patellofemoral pain syndrome • Osteoarthritis • Bursitis | • Worse with stairs, squatting, or sitting for long periods |
Inner side (medial) | • MCL injury • Medial meniscus tear • Osteoarthritis • Bursitis | • May follow a twist or blow to the outer knee |
Outer side (lateral) | • Iliotibial (IT) band syndrome • Lateral collateral ligament (LCL) injury • Lateral meniscus tear • Osteoarthritis | • Common in runners and cyclists • Worsens during activity |
Back (posterior) | • Muscle or tendon strain • PCL injury | • A visible bulge or tightness suggests a cyst |
Above or below the kneecap | • Quadriceps or patellar tendon injury | • May happen after a fall, a bad landing, or from jumping sports |
All over the knee | • Gout | Warning signs include: • Redness • Warmth • Fever |
Knee pain treatment
Although the causes might be different, there are some basic steps you can take if you have knee pain:
Pain medications: NSAIDs, such as ibuprofen or naproxen, are effective over-the-counter (OTC) medications you can take for knee pain. They should only be used for short periods of time though. Also, you should avoid NSAIDs if you have kidney problems or stomach problems such as ulcers.
Ice: Icing the knee can lower pain and swelling.
Rest: Resting or reducing activity for short periods of time may be helpful. You don’t want to stop exercising completely for long periods of time because this can make things worse.
Get help: If your pain lasts a long time (more than 1 week), it’s a good idea to see a healthcare professional to get a better idea of what’s going on with your knee. Sometimes, X-rays can help with the diagnosis. Also, a referral to physical therapy can be helpful. They can show you which exercises to do and how to do them safely.
Best exercises for knee pain
You can improve your knee pain by exercising and stretching to improve strength and flexibility. In fact, exercise is an important part of treating knee pain. Check out this guide for easy-to-do exercises and stretches that can help with knee pain, such as:
Straight-leg lifts
Single-leg dips
Hamstring curls
Wall squats
Step-ups
Quad and hamstring stretches
How to prevent knee pain when running, cycling, or walking
It’s a good idea to protect your knees during exercise to prevent pain and injuries in the first place. Here are some general tips:
Start slow. It takes time for your knees to get strong enough for more intense exercise, so give it some time.
Warm up with gentle exercises. Do these before more intense or sustained activity.
Don’t ignore pain. Pain is a sign that you’re overdoing it, which can lead to overuse injuries.
Stretch after your workouts. This can help lower tightness and soreness and help prevent injury.
When to seek care
Most causes of knee pain are not life- or limb-threatening. But sometimes knee pain can be a sign of more serious illnesses that need prompt medical attention.
Joint infections
Joint infections are a medical emergency. Infected knee joints may have these symptoms:
Fever
Extreme pain in the knee
Redness
Swelling
Knee feels warm to the touch
If you’re concerned about a knee joint infection, see a healthcare professional right away. If you wait too long, the infection can damage your joint, so immediate treatment is important.
Inflammatory conditions
Knee pain could also be a sign of rheumatoid arthritis or other inflammatory conditions. Usually, more joints are involved than just the knee. Joints can be red, swollen, and painful. If you have pain in multiple joints that isn’t improving with simple measures, it’s a good idea to see a healthcare professional.
Trauma
Knee injuries can also be serious at times, especially after trauma. You should have your knee pain checked by a healthcare professional after an injury in these cases:
You heard a pop.
You felt your knee give out.
Your knee pain is severe.
You can't move your knee.
You're limping.
Quiz: Do I need knee replacement surgery?
Frequently asked questions
Yes, sciatica can cause knee pain. But that’s not the usual pattern. Most sciatica involves the L5 or S1 nerve roots, which send pain past the knee and into the calf and foot. A healthcare professional can help you determine the source of your knee pain.
In some cases, a chiropractor may be able to help with knee pain. But it’s best to get a diagnosis from your primary care provider first so you can know what’s causing your pain. A chiropractor may be able to improve joint mobility — which can help with pain when combined with exercise.
Yes, plantar fasciitis can cause knee pain. That’s because you often change how you walk when your heel hurts to avoid the pain. These changes can impact the force applied to your knee, causing knee pain. If you have heel and knee pain, it’s a good idea to have them both looked at together.
Yes, sciatica can cause knee pain. But that’s not the usual pattern. Most sciatica involves the L5 or S1 nerve roots, which send pain past the knee and into the calf and foot. A healthcare professional can help you determine the source of your knee pain.
In some cases, a chiropractor may be able to help with knee pain. But it’s best to get a diagnosis from your primary care provider first so you can know what’s causing your pain. A chiropractor may be able to improve joint mobility — which can help with pain when combined with exercise.
Yes, plantar fasciitis can cause knee pain. That’s because you often change how you walk when your heel hurts to avoid the pain. These changes can impact the force applied to your knee, causing knee pain. If you have heel and knee pain, it’s a good idea to have them both looked at together.
The bottom line
Knee pain is common, and there are many different causes, like inflammation, injury, arthritis, or even decreased activity. You can often improve your knee pain with some simple measures.
In rare cases, knee pain can be a sign of a more serious medical illness, so seeing a healthcare professional for severe pain or symptoms that aren’t improving can be helpful.
Why trust our experts?
References
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FitzGerald, J. D., et al. (2020). 2020 American College of Rheumatology guideline for the management of gout. Arthritis Care and Research.
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Hunter, D. J., et al. (2019). Osteoarthritis. Lancet.
Jevsevar, D. S. (2013). Treatment of osteoarthritis of the knee: Evidence-based guideline, 2nd edition. Journal of the American Academy Orthopaedic Surgeons.
Mehallo, C. J., et al. (2006). Practical management: Nonsteroidal antiinflammatory drug (NSAID) use in athletic injuries. Clinical Journal of Sports Medicine.
OrthoInfo. (n.d.). Anterior cruciate ligament (ACL) injuries. American Academy of Orthopedic Surgeons.
OrthoInfo. (n.d.). Collateral ligament injuries. American Academy of Orthopedic Surgeons.
OrthoInfo. (n.d.). Knee exercises. American Academy of Orthopedic Surgeons.
OrthoInfo. (n.d.). Meniscus tears. American Academy of Orthopedic Surgeons.
OrthoInfo. (n.d.). Patellar (kneecap) fractures. American Academy of Orthopedic Surgeons.
OrthoInfo. (n.d.). Patellar tendon tear. American Academy of Orthopedic Surgeons.
OrthoInfo. (n.d.). Posterior cruciate ligament (PCL) injuries. American Academy of Orthopedic Surgeons.
OrthoInfo. (n.d.). Prepatellar (kneecap) bursitis. American Academy of Orthopedic Surgeons.
Runge, N, et al. (2022). The benefits of adding manual therapy to exercise therapy for improving pain and function in patients with knee or hip osteoarthritis: A systematic review with meta-analysis. Journal of Orthopaedic & Sports Physical Therapy.
van Dijk, G. M., et al. (2006). Course of functional status and pain in osteoarthritis of the hip or knee: A systematic review of the literature. Arthritis and Rheumatology.
