What Does It Mean If My Knee Is Swollen?

What does a Swollen Knee Indicate?

Swelling in the knee, also known as knee effusion or water on the knee, occurs when fluid collects around the knee joint.  Swelling can occur due to many different reasons and apply to all ages of patients.  

While some reasons for swelling can be treated with over-the-counter medication, persistent and constant swelling can lead to tissue damage, bone softening, and cartilage loss.  

The quick answer to what does it mean if my knee is swollen, is that if swelling is accompanied by constant pain and other issues, it is advised to seek medical attention. The following information will include common reasons to explain what does it mean when my knee is swollen.  Below are common treatment methods and when it is advised to contact a doctor. Read this article about knee pain and 5 Knee Symptoms You Should not Ignore

Man placing ice pack on swollen knee. JOI RehabMan with Ice pack on Knee for Swelling.

Causes Of A Swollen Knee

So often in physical therapy, patients ask us "what does it mean if my knee is swollen?"

  • Osteoarthritis– This is the most common cause of swollen knees.  Osteoarthritis is caused by the cartilage in the joint wearing down resulting in a bone-on-bone joint.  This also causes a chemical change in the knee and can create a hostile environment causing pain and fluid to build up in the joint. 
  • Injury or Trauma – Any injury to the bones, ligaments, meniscus, tendons, bursae, or cartilage in the knee can cause pain and swelling. Some serious trauma and injuries can even lead to blood in the joint.  With a vast amount of blood in the joint, significant knee swelling is expected as well as some stiffness and bruising. 
  • Bursitis (Septic and Non-Septic) – Bursa, the small fluid-filled sacs that protect joints, can become inflamed and fill with fluid causing the swelling in the knee.  The joint can become painful and will often feel “squishy” to the affected. Sometimes the bursa can get infected and fill with pus which will also increase swelling in the knee.  This can cause redness and an increase in temperature in the joint. Infrapatellar bursitis can often occur when you bump your knee and cause an extreme amount of pain when kneeling.
  • Tendonitis of the knee - is when one of the knee tendons become irritated or inflamed causing knee pain.

If you would like to learn more about the anatomy of the knee, please watch this video.

How do you treat a swollen knee?

You should utilize the RICE Protocol. This Protocol consist of:

  1. Rest
  2. Ice
  3. Compression
  4. Elevation

Another treatment option is activity modification and over-the-counter medications.

What Does Swelling Above The Knee Mean?

Swelling from within the knee joint can cause the area above the knee to appear swollen.  This can be from several different injuries.  It can be from injuries to the ACL, meniscus or even from a strain or tear to the patellar tendon or quad.  The VMO muscle will not function or contract if there is swelling present in this area.  It is very important to ice this area if swelling is present. 

What does it mean if my knee is swollenKnee Anatomy

Treatment for a Swelling on Side of Knee

With those that have a history of osteoarthritis and swelling after strenuous activity, like a workout or run, over-the-counter medications will help alleviate the pain. Patient may also apply compression sleeves to decrease the swelling during and after activity.   Another way to decrease swelling at home is to use the R.I.C.E. Protocol: Rest, Ice, Compression, and Elevation. 

Swelling in the knee caused by BursitisKnee is swollen from Bursitis


Rest the joint and refrain from hard workouts, sports, and prolonged activity for 24-48 hours.  Normal range of motion should continue to decrease joint stiffening.

RICE Protocol for a Swollen KneeREST for the RICE Protocol


Ice can be applied to the knee 3-4 times a day for 15-20 minutes at a time.  Ice should never be applied directly to the skin.

Ice Bags for a swollen knee Ice for the RICE Protocol


An ace bandage, compression sleeve or socks may not only reduce swelling already present, but may limit knee swelling during activity.

Compression Socks for a swollen kneeCompression Socks for the RICE Protocol


Reducing blood flow to the area by sitting with the leg on a stool or lying down with the foot on a pillow, will reduce swelling. 

Elevation for a swollen kneeElevation Above Your Heart for RICE

When Should I Worry about a Swollen Knee?

In most cases with swollen knees, minimal to moderate knee swelling can be taken care of at home. The quick answer is the following cases are reasons to contact doctor:

  • The knee is unable to full bend or straighten.
  • Knee has a pronounced abnormality or is severely swollen.
  • There is extreme pain in the knee.
  • The patient is unable to walk on the knee and it feels like it is going to “give out.”
  • Area is red and hot.
  • Patient has a fever of 100.4 degrees or higher.
  • Knee has been swollen for 3 days or more.

Related Articles:

If one is uncertain about whether the swelling is serious or not, calling a doctor is a good decision to avoid future damage and resolve an issue within the joint. Hopefully, this article has given you some reasons for "What does it mean if my knee is swollen?".  If the swelling does not go away for an extended period of time, it is probably time to see a JOI Orthopedic Knee Specialist.

By: Amelia Son, PTA 

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