12 Common Sources of Knee Pain

Why does my knee hurt? Get your answer to this question and understand when it's time to see a medical professional about your knee pain.

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Pamela Q. Fernandes Doctor and Medical Writer
Medically reviewed by 

Reasons why your knee hurts and what to do

Maybe you’re one of the 25% of the global adult population experiencing chronic knee pain? Even if you are currently pain-free, read on to find out how you may strengthen your knee joints and prevent damage before it’s too late. We’ll help you identify the reasons for your knee pain when it first starts and prevent further damage. Injurymap provides you with programs to prevent its pain escalation as well as rehabilitate injuries.


Common Sources Of Knee Pain

Identifying the source of knee pain comes first. Is it the joint or the cartilage? Is it inflammation or injury? Do you rate the pain at 7 or higher out of 10? Answers to these questions will vary depending on the location and severity of your condition. The list below focuses on the most common causes of injury. There are some additional, rarer causes of knee pain. So you should always visit your medical professional if your pain is persistent and severe.


1. Jumper’s knee

Most common in athletes who perform activities involving a lot of jumps or kicks, jumper’s knee is an overload injury that can affect non-athletes, too. At the root is a large tendon running across your kneecap from the thigh muscle (the quadriceps) and connecting the kneecap to your shinbone.

It is he kneecap tendon(ligamentum patellar) that becomes irritated and damaged when you suffer from jumper’s knee. If the injury progresses over several weeks, it may become tendinopathy.

Pain in the bottom part of the kneecap is a common symptom if you have jumper’s knee. It’s generally brought on by the start and end of physical activity. The pain usually subsides as your knee warms up. Some people will experience pain from performing everyday activities like climbing stairs.

Rehabilitating jumper’s knee means placing special emphasis on slow and heavy strength-building exercises, as well as exercises stretching the thigh muscles.

It’s important you don’t increase the load on your kneecap tendon too quickly. Additional mobility and flexibility exercises will help you create optimal conditions for the kneecap to work in and help prevent future injuries.Read our full article on jumper’s knee here

2. Runners knee

It is the common term used to describe any one of several conditions that cause pain around the kneecap, also known as the patella. These conditions include patellofemoral pain syndrome and iliotibial band syndrome. Runner’s knee is quite common and accounts for 25 percent of all injuries in runners.

The main symptom of runner’s knee is dull ache felt around the kneecap. The pain develops slowly over time. You may feel some discomfort immediately after running. The symptoms may also intensify if you’re climbing stairs or squatting.

Surgery is very rarely required to treat runner’s knee. Conservative treatment is usually successful in controlling the pain. The most effective treatment for runner’s knee is rest and building strength with exercises.

Read our full article on runner’s knee here

Trauma or Injury

3. Fractures

Any injury, trauma or severe fall can cause fractures to the bones in your knee. There are several bones in your knee joint: the tibia, femur, fibula, and patella. The patella is the most important of them all.

Bones are strong and shouldn’t get injured easily, but the patella is particularly vulnerable as it sits at the top of your knee, protecting and connecting all the bones beneath. If you have weak bones due to osteoporosis or low calcium levels, simply getting out of the bathtub could cause the patella to fracture.

Broken kneecap / Patellar fracture

If the bones in your knee are fractured, you will experience a grating feeling when you move your leg or when the bones grind against each other.

Depending on the type of fracture you have, the treatment will be varied. If the fracture is severe, causes you to howl in pain or is more than just a crack, surgery might be your best bet. However, if it’s a simple hairline fracture, then rest, a brace and physical therapy might be helpful.

4. ACL Injury

The ACL is the anterior cruciate ligament. It is one of a major pair of ligaments that anchors the knee joint and prevents excessive motion. It provides about 80% of the restraining force to any forward displacement of your shinbone (tibia) and thus stabilizes your knee joint. The ACL is also the most commonly injured ligament of the knee joint. Sports, vehicular accidents, lateral blows to the knee can all cause the ACL to tear.

Most people experience a loud “pop” in their knee when their ACL tears. They feel that the joint is unstable or gives way rather easily when they stand. Additionally, their range of motion is limited and, if the tear is severe, they may even experience joint swelling and pain. If the tear is minor, you might be able to make do with anti-inflammatory drugs and crutches to keep the weight off the knee. Knee muscle strengthening exercises can also help. Severe tears, as seen in athletes, may require surgery.

5. Meniscal Tears

The menisci are rubbery cartilages between your shinbone (tibia) and thighbone (femur). They act as shock absorbers for your knee joint every time your foot comes in contact with the ground and sends the propulsive energy upwards. The menisci can tear due to many reasons. Repeated hard movements can wear down the menisci and make them fragile. Alternatively, they can tear if your knee suddenly twists or rotates while the foot remains planted. If you have this, you might experience your knee getting “locked” without warning. You may also have difficulty bending and straightening the leg.

Often, people don’t even realize they have a meniscal tear. With time though, your movement will be affected. If you have a tear in the outer “red zone” of the menisci which is suffused with good blood supply, rest is more than enough for your injury. However, if the tear is in the inner “white zone” where there is little blood supply you might need treatment.

Mechanical Issues

6. Dislocated Knee-Cap And Knee Joint

The knee-cap or patella can get dislocated, that is, completely shifted outside of its groove. This can cause you considerable knee pain, as the patella comes to rest outside of the knee joint. There may be visible swelling and an inability to straighten the leg. A dislocated knee-cap is very different from a dislocated knee joint. When your knee joint is dislocated, the tibia and femur lose complete contact from one another. Both cause knee pain and it’s important you get this checked.

Dislocated kneecap / Patellar dislocation

Knee-cap dislocations can be treated very quickly by repositioning the patella back into place. You may find that after the first patella dislocation, the knee-cap tends to slip or subluxate more easily. As a result, repeated knee-cap dislocations occur. Knee joint dislocations have to be surgically corrected and cause more severe knee pain.

7. Referred Pain From Hip Or Foot

Injuries or pain in the foot or hip might be referred to the knee joint causing what is called as referred or radiating pain. However, sometimes injuries in the hip or ankle can cause you to alter your gait. As the gait changes, your knee tends to bear a lot more weight and this stresses the joint. With the added stress, over and above the usual wear and tear that it experiences, you might feel knee pain.

In these cases, the knee pain may be your body’s way of telling you that the joint is taking on too much. Referred pain may be throbbing, dull and pulsing. It may get exacerbated only on movement. To deal with referred knee pain you need to strengthen the muscles of the other joints through physical therapy like ankle stretches or hamstring exercises. Or you can treat the other joint disorders - before they permanently damage your knee.

8. Loose Body

This is when a piece of cartilage, collagen or bone floats into the joint space and causes knee pain. This usually occurs with age, as your cartilage and bones undergo wear and tear. Usually, it’s not a problem and isn’t noticeable - until it affects movement. The floating piece may prevent full extension or flexion of your knee joint. It’s like a trapped fly in a jar. And the interference of the floating piece may cause you bursts of knee pain.

Most people can continue to function with the floating loose body. Often these floating bodies can vary in size from a few millimeters to a few centimeters. You can continue to withstand occasional pain and function, but the floating bodies can nick your cartilage and damage blood vessels.

The real trouble occurs when the loose body gets trapped and then inflames the joint. As long as they float, they will mildly irritate the joint surfaces. However, when they get trapped between the cartilaginous surfaces of two bones, for example, your tibia and femur, they will produce inflammation. The inflammatory processes, in turn, yields to symptoms of knee pain, swelling, and joint locking. Then, you may require arthroscopic removal of the loose piece.

Chronic inflammation due to the loose body can hasten osteoarthritis, so it’s not something you want to ignore.

Degenerative Disorders

9. Osteoarthritis

While a hundred different types of arthritis exist, osteoarthritis is the most common. This happens with age and degeneration of your body. Over time, small pieces of bone called osteophytes can grow into the joint space and damage the cartilage cushion between your tibia and femur.

Osteoarthritis of the knee

Gradually as the cartilage thins and the bony spurs grow, your joint space may become thinner. The bony hardness in the joint can prevent the normal fluid motion that the cartilage allows. Your reduced range of motion will cause knee pain and inflammation. With time, as the cartilage is destroyed, your knee pain will increase considerably as the inflammation progresses.

Treatment of osteoarthritis depends on how far it has progressed but it can be prevented by maintaining the strength and flexibility of your joints. You can do this by doing regular strengthening exercises. You can also work on reinforcing your thigh muscles, so they can stabilize the knee joint better and keep it flexible.

Chekc out our article on Osteoarthritis here

10. Gout

Gout is a condition where the uric acid builds up in your blood. The uric acid cumulates and forms crystals in the joint space. These crystals can cause sudden, sharp knee pain with redness and swelling.

This inflammatory condition often affects the big toe but it also affects the knee joint causing severe knee pain. Gout can be excruciating. One of the ways of handling this pain is controlling your diet and alcohol intake. Avoid foods rich in purines like veal, shellfish, trout, bacon, and turkey. Purines are broken down in your body to form uric acid. Sometimes the enzymes responsible for the breakdown don’t work well, leading to an increase in uric acid. If your knee pain due to gout cannot be controlled through a diet, then you’ll need medications that prevent the formation of uric acid crystals.


11. Septic arthritis

Septic arthritis is an infection of your knee joint. This occurs when bacteria from another part of your body enters the joint via the bloodstream. Often, the joint will be angry red, swollen. You may also have a fever. The accompanying knee pain will be sharp and so debilitating that walking is simply out of the question.

Septic arthritis is common in individuals with lower immunities, infants, elderly people and people receiving chemotherapy. The synovial lining of your knee joint offers little in terms of protection to the joint and cannot fight off an infection. Alternatively, a puncture wound or an accident can expose the joint and cause septic arthritis.

This can become a medical emergency if left untreated. You will need intravenous antibiotics and if the joint space is too swollen, it may have to be drained. If you have any symptoms of septic arthritis, visit your doctor immediately as the infection can spread throughout your bloodstream very quickly.

Connective Tissue Disorders

12. Rheumatoid Arthritis

Connective tissue disorders like rheumatoid arthritis can cause severe knee pain. This is an autoimmune disease where your body attacks its own organs and joints. It’s symmetrical, so if it affects one knee, it will affect the other.

After being repeatedly attacked by the body, your synovial lining starts to get inflamed, swollen and stiff. This results in chronic knee pain. Rheumatoid arthritis can be treated with medication that helps control inflammation.

Once you control the pain, it’s a good thing to keep the joint active and flexible with regular physical therapy. While you cannot prevent the disease, you can prevent it from worsening by having it checked early.

When To See A Doctor For You Knee Pain

Most knee pain can be handled with rest and physical therapy. If your condition is worsening, you must see a doctor to identify the cause. Often, they will ask you to do a blood test and also get X-rays to visualize the bones and joint space. There are a few red flags you must pay attention to seek medical help when you see them.

  • The Inability to Bear Weight: If you find you cannot bear any weight at all on your knee joint, then it’s time to investigate this further. Partial tears and injuries will allow limited mobility of your joint. However, an inability to bear weight and move is serious.

  • Out of Proportion Pain: If you’re howling in pain and it’s just excruciating even with your pain medications, schedule a visit with your doctor now. Bone pains are usually very severe and need to be looked at to make sure there’s no cancer or growth there.

  • Fever, fatigue, body ache: If you’re experiencing, generalized bodyache, fatigue, and fever, then this is more than just your knee joint and will require a detailed physical exam and blood tests. Systemic signs of illness as these need to be checked to rule out sepsis.

  • Locking: The knee joint is not meant to get locked. It has a complex series of ligaments and tissues that prevent it from locking. If your knee is repeatedly getting locked and it’s affecting your range of motion, seek medical help.

  • Swelling/Effusion: Joint swelling that doesn’t resolve in a week needs to be looked at carefully. You don’t want it to turn into septic arthritis. Additionally, if you feel like there’s fluid in the joint, it needs to be seen by your doctor.

  • Bilateral: If the knee pain is bilateral, then it could be an autoimmune condition. Autoimmune conditions should be investigated since they can affect all your joints and not just your knee.

  • Other Joint Involvement: If it’s not just knee pain, but you have shoulder pain or any other joint that is involved or hurting, you need to see a doctor to rule out any systemic illness.

  • Hip: If you have hip pain accompanying the knee pain, then you must get a consultation. This is because avascular necrosis of the neck of the femur is common and has a delicate blood supply.

Treatment of Knee Pain - R.I.C.E.

You can treat most knee pain by remembering the word R.I.C.E

The R.I.C.E. principle

  • Rest: If you have knee pain, stop using the joint as much. Yes, you’d be able to perform limited sports and movement but don’t stress the joint. Rest will allow it to heal and clear the inflammation.

  • Ice: Use ice or cold compresses to ease your pain. This will cause the blood vessels to constrict and decrease the inflammation in the joint.

  • Compression: Use a brace or a compression bandage to keep the swelling at bay.

  • Elevation: Allow gravity to work for you. By elevating your leg, you encourage increased blood return to the knee joint and don’t allow any weight on the joint. This will hasten the recovery process.

Pain medications like ibuprofen and acetaminophen are also great for acute pain. You can take these medications if the pain is unbearable.

Preventing Knee Pain

You can certainly prevent knee pain. Certain risk factors make us more susceptible to knee pain. Here are some, you should be aware of:

Increased WeightThis includes being overweight or obese. A higher weight put more pressure on your knee joints and accelerates the breakdown of the cushioning cartilage. If you don’t have strong muscles to stabilize the joint or are not flexible enough, the knee joint will gradually become more susceptible to wear and tear.

Sports RelatedIf you’re a hardcore basketball player or runner, the pounding your knees take can result in knee pain. While there are advantages to playing sports, sports like volleyball, basketball, and others can be hard on your knees. You may want to switch to activities with less impact, such as swimming or cycling.

OccupationalOften certain jobs like construction can also affect your knee joints. Knee loading activities are detrimental to your knee joints. In fact, studies have shown that longer and cumulative exposure to kneeling and squatting at work, leads to a higher occurrence of osteoarthritis of the knee joint. Add to that, any climbing and lifting and you have a cocktail of knee joint problems.

Recurrent Knee InjuriesAlso, if you’ve experienced knee injuries, then you may have an increased risk of knee injuries in the future. Several studies have revealed that recent and recurrent knee injuries tend to accelerate knee osteoarthritis. The evidence shows that after any joint trauma, the odds of having knee osteoarthritis rises by 3 to 6 times, compared to individuals without a history of a knee injury. What’s even more concerning, certain knee injuries like meniscal root injuries undergo accelerated knee osteoarthritis. Older age and higher weights can add to this accelerated degeneration of the joint.

Knee Pain Prevention: First Steps

Despite the above risk factors, you can prevent knee pain by keeping off the weight. Stay light and maintain a healthy weight. Work regularly to build and strengthen your muscles. Injurymap has a great program to help you do this. Build up your muscles and keep them flexible through consistent training. Follow the right technique and stay the course.

Start slowly. Do exercises that are easy on the knees. You can get enough cardio through swimming or water aerobics. Not all cardio is hard on the knees. You can always swap out your exercises when your knee pain gets worse. For those dealing with chronic knee pain, you’ll find that self-management through a regular program can work wonders for you.

Physical Therapy For Knee Pain

One of the major components of rehabilitation for knee pain is physical therapy. Our app has a series of exercises to help you work on all the muscles that stabilize the knee joint. In fact, at some point, it should become your mainstay to treating your knee pain.

Start SlowYou don’t have to go do it all at once. Straight leg raises and quad sets while lying down should be good enough while you deal with pain. Once the pain eases, you can do more complex exercises. This is particularly important if you haven’t been active for a while. The goal here is to ease your joints into exercise. Don’t push yourself too hard. By doing so, you will overwork your muscles, strain the joint and worsen the knee pain.

Build Over TimeYou don’t have to go do it all at once. Straight leg raises and quad sets while lying down should be good enough while you deal with pain. Once the pain eases, you can do more complex exercises. This is particularly important if you haven’t been active for a while. The goal here is to ease your joints into exercise. Don’t push yourself too hard. By doing so, you will overwork your muscles, strain the joint and worsen the knee pain.

Get HelpDon’t go it alone, especially if you’re new to physical therapy. Working with a trainer or a visualized program is better because it can help you identify your trouble spots. Do you have bad balance? Is a particular muscle group weak? Is the joint too stiff? Can you work out with pain? You will need an expert to answer these questions. Injurymap’s personalized exercises are simple and you can do them at home. You can also show them to your doctor and work with them to identify targets for your knee pain.

Initially, you may be asked to simply flex your knee multiple times. This may seem silly but it’s a gradual step up. Once you’ve learned the basics and have established a foundational routine, you can step up through the program, but you will need some hand-holding in the beginning.

Reduce Medication DependenceThere’s enough data to prove that pain medications are highly addictive. Doctors are asking patients to exercise caution with narcotics and pain medications. By choosing physical therapy, you can reduce your dependence on pain medications and avoid the myriad of side effects associated with their use. They are unsafe at high doses, prolonged use and worse in the elderly or frail members of the populace. Physical therapy is a great alternative to wean yourself off these medications. You can save them for flare-ups of pain episodes. With time, you may find that the flare-ups may also decrease as the joint is more stable, flexible and the muscles are stronger.

Knee Pain Can Get Better

You don’t have to live all your life with knee pain. At some point, something’s gotta give and it doesn’t have to be your knee. You cannot be dependent on pain medications forever. At Injurymap, we work closely with doctors and therapists to create a program for individuals with joint pain. Since knee pain is so common, we designed the app to answer all your pain questions and make it easier for you to get physical therapy without breaking the bank.

At present, physical therapy is one of the cornerstones of therapy for knee pain. The Orthopedic Section of the American Physical Therapy Association (APTA) lists physical therapy as a guideline in the treatment of knee pain. So much so they call them therapeutic exercises. Studies have confirmed that physical rehabilitation of the knee joint, improves the range of motion of the knee, quadriceps strength, reduces pain and functional disability.

Traditional physiotherapy, while great, is time constricted. Injurymap is quick, available and has programs designed by doctors with your knee pain in mind. So take the first step towards getting rid of that knee pain and sign up for a low cost program. Knee pain shouldn’t last forever and we can help you do that.

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About the author

Pamela Q. Fernandes is a doctor, author and medical writer. Having practiced preventive and family medicine for the last ten years, she's a keen advocate of health education and preventive medicine in her medical practice.