Knee Pain

We're sorry you have knee pain!

The goal of this guide is to provide information while awaiting evaluation with your doctor, or for additional information after you have seen him or her. Please keep in mind that this guide is not intended to replace a face-to-face evaluation with your doctor. The diagnoses provided are among the most common that could explain your symptoms, but the list is not exhaustive and there are many other possibilities. In addition, more than one condition may be present at the same time. For example, a person with rheumatoid arthritis could also have tendonitis.

The knee's complicated anatomy allows the strength, stability and flexibility of this important joint.

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By answering just a few questions, it's usually possible to sort out whether your knee pain could be due to something serious.

Along with your knee pain, do you have one or more of the following:

  • fever

  • redness over or around the knee

  • marked swelling of the knee

  • inability to use the knee (for example, is it impossible for you to bear weight?)

  • a recent, significant injury to the knee such as a fall or a motor vehicle accident?

Yes, I have or had one or more of these.

No, I have had none of these.

This question has two parts and is intended to identify mild knee pain that is likely to get better on its own. Examples of problems that can cause mild knee pain like this are mild sprains and strains.

1) Would you consider your knee pain mild? That is, despite your knee pain, are you still able to do most or all of your regular activities without too much difficulty?

and,

2) Has your knee pain been going on for less than three weeks?

Yes to both questions.

No to one or both questions.

From your answers so far, it does not seem that your knee pain is clearly serious, requiring urgent evaluation, but it is also not clearly mild. So, a few more questions can be helpful to sort out the most likely cause of your pain.

The most common causes of knee pain are different in people of different ages.

Are you at over 45 years old?

Yes, I am more than 45 years old.

No, I am 45 or younger.

It's helpful to know whether any other joints are bothering you because some conditions that cause knee pain often cause pain in other joints as well. Rheumatoid arthritis is a good example of this.

Do you have pain and/or swelling in other joints?

Yes, I have pain and/or swelling in other joints.

No, only my knee bothers me.

Some joint pain is due to joint inflammation (or arthritis), often with joint swelling, while other causes of joint pain come with little or no inflammation and swelling.

Do you have swelling in your painful knee?

Yes, my painful knee is swollen.

No, my painful knee is not swollen.

To recap, you are age 45 or younger, no other joints are bothering you besides the sore knee, and there is no swelling in the sore knee.

There's just one more question. It has two parts:

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

Based on your answers (you are age 45 or younger, joints other than your knee are not bothering you, your painful knee is not swollen and there is no locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • tendonitis

  • bursitis

  • osteoarthritis

  • chondromalacia patella

  • trauma/sports injury.

Click here to continue.

Based on your answers (you are age 45 or younger, only your knee is bothering you, your painful knee is not swollen but there is locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • cartilage damage and/or ligament damage

  • tendonitis

  • bursitis

  • trauma/sports injury

  • chondromalacia.

Click here to continue.

To recap, you are age 45 or younger, no other joints are bothering you besides the sore knee, but there is swelling in the sore knee.

There's just one more question. It has two parts:

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

Based on your answers (you are age 45 or younger, joints other than your knee are not bothering you, your painful knee is swollen but there is no locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • crystal-induced disease such as gout, especially if you are male

  • cartilage damage and/or ligament damage

  • trauma/sports injury

  • isolated arthritis, as in spondyloarthropathy

  • infection, including Lyme disease.

Click here to continue.

Based on your answers (you are age 45 or younger, no joints other than your knee are bothering you, your painful knee is swollen and there is locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time) including:

  • cartilage damage and/or ligament damage

  • isolated arthritis of the knee (for example, spondyloarthropathy)

  • infection, though this is less likely (for example, Lyme disease, septic arthritis)

  • crystal-induced disease (such as gout, especially if you are male.

Click here to continue.

Some joint pain is due to joint inflammation (or arthritis), often with joint swelling, while other causes of joint pain come with little or no inflammation and swelling.

Do you have swelling in your painful knee?

Yes, my painful knee is swollen.

No, my painful knee is not swollen.

To recap, you are age 45 or younger, other joints are bothering you besides the sore knee, and there is no swelling in the sore knee.

There's just one more question. It has two parts:

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

Based on your answers (you are age 45 or younger, joints other than your knee are bothering you, your painful knee is not swollen and there is no locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • early rheumatoid arthritis or related condition (for example, spondyloarthropathy)

  • fibromyalgia

  • tendonitis

  • bursitis

  • chondromalacia.

Click here to continue.

Based on your answers (you are age 45 or younger, other joints are bothering you, your painful knee is not swollen and there is locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time) including:

  • rheumatoid arthritis or a related condition (for example, spondyloarthropathy)

  • cartilage damage and/or ligament damage

  • fibromyalgia

  • chondromalacia.

Click here to continue.

To recap, you are age 45 or younger, other joints are bothering you besides the sore knee, and there is swelling in the sore knee.

There's just one more question in this guide. It has two parts and it deals with "mechanical symptoms," such as locking or giving way. When present, these symptoms raise the possibility of torn cartilage or an injured ligament.

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

Based on your answers (you are age 45 or younger, joints other than your knee are bothering you, your painful knee is swollen but there is no locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • rheumatoid arthritis or a related condition (for example, spondyloarthropathy)

  • crystal-induced disease such as gout, especially if you are male

  • infection, including Lyme disease.

Click here to continue.

Based on your answers (you are age 45 or younger, joints other than your knee are bothering you, your painful knee is swollen and there is locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • cartilage damage and/or ligament damage

  • torn meniscus

  • anterior cruciate ligament (ACL) injury and posterior cruciate ligament (PCL) injury

  • rheumatoid arthritis or a related condition (for example, spondyloarthropathy)

  • crystal-induced disease(such as gout, especially if you are male

  • infection, including Lyme disease.

Click here to continue.

It's helpful to know whether any other joints are bothering you because some conditions that cause knee pain often cause pain in other joints as well. Rheumatoid arthritis is a good example of this.

Do you have pain and/or swelling in other joints?

Yes, I have pain and/or swelling in other joints.

No, only my knee bothers me.

Some joint pain is due to joint inflammation (or arthritis), often with joint swelling, while other causes of joint pain come with little or no inflammation and swelling.

Is your painful knee swollen?

Yes, my painful knee is swollen.

No, my painful knee is not swollen.

To recap, you are older than 45, no other joints are bothering you besides the sore knee, and there is no swelling in the sore knee.

There's just one more question. It has two parts:

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

Based on your answers (you are older than 45, your knee is the only joint that's bothering you, your painful knee is not swollen and there is no locking and/or giving way of the knee), there are a number of conditions that could be causing your knee pain. More than one may be present at the same time, including:

  • osteoarthritis

  • bursitis

  • tendonitis.

Click here to continue.

Based on your answers (you are older than 45, no other joints are bothering you, your painful knee is not swollen and there is locking and/or giving way of the knee), there are a number of conditions that cause your knee pain. More than one may be present at the same time, including:

  • osteoarthritis

  • cartilage damage and/or ligament damage.

Click here to continue.

To recap, you are older than 45, no other joints are bothering you besides the sore knee, and there is swelling in the sore knee.

There's just one more question in this guide and it deals with "mechanical symptoms," such as locking or giving way. When present, these symptoms raise the possibility of torn cartilage or an injured ligament.

This question has two parts:

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

Based on your answers (you are older than 45, no other joints are bothering you, your painful knee is swollen and there is no locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • osteoarthritis

  • crystal-induced disease such as gout and pseudogout

  • infection (less likely)

  • ligament or cartilage damage (though one of these would be even more likely if you had locking or giving-way)

  • other type of arthritis called spondyloarthropathy.

Click here to continue.

Based on your answers (you are older than 45, no other joints are bothering you other than your knee, your painful knee is swollen and there is locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • osteoarthritis

  • cartilage damage and/or ligament damage

  • crystal-induced disease such as gout and pseudogout

  • infection (less likely).

Click here to continue.

Some joint pain is due to joint inflammation (or arthritis), often with joint swelling, while other causes of joint pain come with little or no inflammation and swelling.

Do you have swelling in your painful knee?

Yes, my painful knee is swollen.

No, my painful knee is not swollen.

To recap, you are older than 45, other joints are bothering you besides the sore knee, but there is no swelling.

There's just one more question. It has two parts:

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

Based on your answers (you are older than 45, joints other than your knee are bothering you, your painful knee is not swollen and there is no locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • tendonitis

  • bursitis

  • osteoarthritis

  • rheumatoid arthritis or a related condition

  • fibromyalgia.

    .

Click here to continue.

Based on your answers (you are older than 45, other joints are bothering you, your painful knee is not swollen and there is locking and/or giving way of the knee), there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • osteoarthritis

  • cartilage damage and/or ligament damage

  • rheumatoid arthritis or a related condition.

Click here to continue.

So far, you've told us you are older than age 45, joints other than your painful knee also bother you and there is swelling in your knee.

Just one more question. It has two parts:

1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?

and

2) Are there times when your knee will not support you?

Yes, to one or both questions.

No, to both questions.

From your answers (age greater than 45, other joints are bothering you, the painful knee is swollen, but not locking or giving way), a number of possible conditions could be causing your knee pain, including:

  • osteoarthritis

  • rheumatoid arthritis or a related condition (such as spondyloarthropathy)

  • crystal-induced arthritis such as gout or pseudogout

  • some combination of these.

Click here to continue.

Based on your answers that you are older than 45, other joints are bothering you, your painful knee is swollen and there is locking and/or giving way of the knee, there are a number of possible causes of knee pain. More than one may be present at the same time, including:

  • osteoarthritis

  • rheumatoid arthritis or a related condition (such as spondyloarthropathy)

  • cartilage damage (may also be called a torn meniscus

  • ligament injury, including anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) injury

  • crystal-induced disease such as gout and pseudogout.

Click here to continue.

Here's the good news! You may have knee pain due to a minor sprain or strain that will get better over time with treatments you can do on your own. But, then again, it can be quite hard to predict these things.

Try the "conservative" route:

  • rest; avoid those activities that you think may have triggered the knee pain

  • ice (for the first 48 hrs. after a minor injury)

  • ointments or creams, such as Ben Gay or IcyHot

  • brace/ACE wrap -- you can find these in surgical supply stores or many drug stores

  • non-prescription pain relievers, such as acetaminophen or ibuprofen (unless your doctor has instructed you to avoid these).

If your knee pain persists, return to this decision guide for more information. In the meantime, try the treatments above.

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You have symptoms that may be present with a serious cause of knee pain, such as infection or fracture.

While many people have these symptoms without a serious cause of knee pain, it is important that you contact your doctor promptly to be evaluated. It may be helpful to return to this decision guide after evaluation.

For fractures, infection, or other serious knee problems, surgery may be necessary. While fractures involving a joint may eventually lead to arthritis, most heal well with a return to normal function.

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The following are conditions that may cause knee pain:

  • ankylosing spondylitis - a form of arthritis with prominent back pain

  • anterior cruciate ligament (ACL) injury

  • arthritis associated with inflammatory bowel disease - a form of arthritis that may accompany Crohn's disease or ulcerative colitis

  • bursitis - inflammation of a bursa near the knee

  • chondromalacia - a softening or irritation of the cartilage under the knee cap

  • fibromyalgia - a cause of diffuse pain

  • fracture - a broken bone

  • gout - a form of arthritis caused by uric acid crystals

  • joint infection, including Lyme disease

  • knee sprain - stretched or torn ligaments near the knee

  • osteoarthritis - a form of wear and tear, or degenerative, joint disease

  • posterior cruciate ligament (PCL) injury

  • pseudogout - a form of arthritis caused by calcium crystals

  • psoriatic arthritis - a form of arthritis associated with psoriasis

  • Reiter's syndrome - a form of arthritis that may follow urinary, genital or bowel infection

  • rheumatoid arthritis - a cause of arthritis affecting multiple joints

  • spondyloarthropathy- see ankylosing spondylitis, arthritis associated with inflammatory bowel disease, psoriatic arthritis, or Reiter's syndrome above

  • tendonitis - tendon inflammation

  • torn meniscus - a form of cartilage damage or injury.

Please click here to exit the guide.

You have completed the knee pain decision guide. We hope your knee pain goes away quickly but if it does not, please return here to update your symptoms and to find more information. Remember, if your knee pain:

  • is severe

  • impairs your ability to walk

  • followed significant injury

  • is associated with fever or marked swelling

you should see your doctor right away or even proceed to an emergency room. It may be helpful to return here later once your initial evaluation has been completed.