Swollen knee without pain

Overview - swollen knee without pain

Your knee can swell when excess joint fluid accumulates in or around your knee. This swelling can have many causes from a simple injury, to arthritis, bursitis or synovitis. Even the bony parts of the knee can appear puffy if your knee is very swollen. The symptoms can vary based on the real cause of the swelling.

If you have synovitis the knee swells and can be painful, but there's no pain at all for some. Often people only feel a tiny bit of pain even if his or her knee is larger than the other. Only your doctor will be able to find out the real cause, and prescribe the appropriate treatment for you.

Sometimes the fluid buildup is just a natural reaction of your body, as it tries to surround your knee with protective fluid.

With the excess fluid you'll find it difficult to use your knee properly, bending or straightening it can be painful.

If your knee is bruised it's a sign that you had an injury. Take a mental note of this, as the doctor may ask it when examining your knee.

Often the swelling is easily cured, so there is no need to panic. Just make sure you visit your doctor as soon as possible.

If you have a stiff knee with pain in the back of the knee you may want to check this article too. Pain on the inner side of the knee is another syndrome that can have different causes.

Stabilizing braces often help with this issue.

Simplified overview: synovial joint.
Simplified overview: synovial joint.

The most common cause: synovitis

In synovitis your synovial membrane becomes inflamed. This membrane is a thin layer that lines most of the joints, including the knee. When the membrane gets inflamed, it tends to produce excess joint fluid, which makes the knee swell. As the synovial membrane extends to other parts of the joints this swelling can be very dramatic.

Synovitis can be either chronic or acute. If it's chronic it flares up and then subsides fast, however if it's acute it will keep coming back even if your knee is just a tiny bit overloaded.

Children can get a third form of synovitis called transient synovitis, which is usually caused by viral infections like chicken pox.

A fourth kind of synovitis is Pigmented Villonodular Synovitis which causes a rust-colored pigmentation in the blood. In PVNS knee tumors tend to occur too, fortunately these are of the benign kind.

A fifth kind is subclinical synovitis. In subclinical synovitis the symptoms are not that pronounced, and you can live a full life with your knee sometimes misbehaving: you may get a bit of pain or water after a long walk but it will be hard to tell the exact cause.

Subclinical synovitis often comes together with arthritis.

What are the long term effects of synovitis?

In the long term the excess fluid can harm both the muscles and the various structures of the knee. It could lead to the thigh muscle weakening, and to cartilage defects and cartilage loss.

Synovitis can cause bone marrow lesions too.

More details of the synovial joints.
More details of the synovial joints.

What is the cause of synovitis and knee swelling without pain?

Often it's hard to find out the cause of the synovitis, as a minor injury which seemingly made no harm may result in the overproduction of joint fluid and can cause the knee to swell.

Synovitis does not alway cause pain, but it causes the knee to swell, feel puffy and sometimes warm too. Chronic synovitis can lead to joint damages as the inflammation attacks the healthy parts of your knee.

Besides the swelling the knee may become red, painful and you may have a popping feeling in it once loaded.

How is synovitis diagnosed?

Synovitis is diagnosed by a trained doctor. He or she will take a look at your knee to see how swollen it is and if it's red. During the examination a small bit of the joint fluid will be extracted using a needle, and the fluid will be examined as this can determine the exact cause of the swelling.

Extracting the joint fluid will lead to a short-term relief too. The lab will analyse the joint fluid: it's color, clarity, viscosity, and the white blood cell count. This helps determining the cause of the synovitis and status of the joint.

During the diagnosis X-ray or ultrasound is usually used to have a look inside the knee.

How to treat synovitis?

Synovitis is treated mainly with anti-inflammatory drugs (NSAIDs) and corticosteroids to reduce the inflammation and pain. Resting and icing the knee combined with elevation works very well too.

If you have gout too, colchicine can work better than NSAIDs.

If the synovitis is caused by bacteria, your doctor will prescribe antibiotics too to kill them off.

If there is a large amount of fluid around the knee it can be drawn out, however it only keeps the symptoms at bay for a short time.

If the synovial membrane is very damaged, the inflamed part is removed with a surgery.

Are there any home remedies for a swollen knee?

If you'd like to improve your swollen knee at home, make sure you rest your knee. Standing too much will make the swelling worse. When you rest make sure your knee is elevated, this helps your circulation in transporting the fluid away.

Icing your knee can help too. Gel ice packs are very useful for this, just make sure you warp them in a soft towel so they will not cool your knee down too much, and won't bruise your skin.

To further reduce the load on your knee, use crutches while it's healing.

Massaging your knee to reduce the swelling can help even more, just make sure you ask your doctor before starting it.

To massage your knee use light pressure and move the skin over your knee in circles to stretch the tissue. Stop once your skin softens up, and change to stroking your thigh from your knee up towards your hip to move the water out of your knee.

Exercise for swollen knee - swimming

Initially when your knee still has a hard time wearing your weight, swimming is one of the safe bets, as it's really easy on the joints.


Ball squats.

Exercise for swollen knee - ball squats

For wall squats stand with your back against a wall, and place an exercise ball between your lower back and the wall. Slowly let your body down into a squat, make sure you start slow and do not go too deep at first. Half squats, when your thigh is at 45 degrees in the end are enough. When you squat your knee should not move in front of your feet. If it does move your feet a bit to the front.

Hold the bottom position for 10 seconds, then gently raise your self back up, wait 10 seconds again and repeat. Work yourself up to 3 sets of 15 reps.


Straight leg raise.

Exercise for swollen knee - straight leg lift

Lie on your back with your healthy leg bent at the knee and your foot resting on the floor for support.

Lift you injured leg off the floor, up to 45 degrees and hold this position for 10 seconds, the slowly let it back down. Repeat with your other leg and work yourself up to 3 sets of 10 repetitions.


One leg balancing.

Exercise for swollen knee - one leg balancing

For one leg balancing, stand next to a table or chair and hold on to it for support.

Lift one of your feet off the ground and hold this position for a minute, then repeat it with your other leg. This exercise will improve your balance and knee stability, and reduces the chances of a fall or an injury.

How to prevent your knee from swelling again?

If you have arthritis, either rheumatoid or osteoarthritis, you are more likely to get a swollen knee. Tracking the arthritis with the help of your doctor will lessen the chance of your knee swelling.

Strengthening your leg muscles is a great idea, however this can put a bit too much load on your knees. Switching to a joint friendly sport such as swimming or water aerobics will lessen the load on your knees and thus the chance of swelling too.

The swelling in your knee is caused by inflammation and this can further degrade your knee joint. So treating the swelling as soon as possible and visiting your doctor is important to avoid any negative long term effects on your knee.

What to buy for a swollen knee?

If you have a swollen knee, ice gels wrapped in soft cloth or towel are great for icing it.

Crutches and sleeves help by taking the load of your knees.

Knee with prepatellar bursitis.
Knee with prepatellar bursitis.

Other cause #1: Housemaid's Knee, also known as pre-patellar bursitis

If you have Housemaid's Knee, the bursa, which are small sacks full of fluid at your knee, get inflamed. This mainly causes swelling under knee cap.

The bursa lessen the friction between the tissues as you move your knee. If you overuse your knee the bursa can get inflamed, usually at the top of the kneecap or on the inner side of the knee.

Pre-patella bursitis symptoms

In Housemaid's Knee the front of the kneecap can become tender, swollen and warm to the touch. While kneeing can be painful, pre-patellar bursitis is not always painful.

In chronic bursitis you may feel a tender lump under your skin at the kneecap.

What causes Housemaid's knee?

Housemaid's knee is most often caused by the irritation of the bursa from kneeing a lot, that's why it's common in jobs where you can't avoid kneeling, for example carpet layers, plumbers and gardeners often get chronic bursitis.

A fall or a direct blow (often seen in wrestling, football or volleyball) to the knee can cause bursitis too. Such a blow can rupture the blood vessels which end up bleeding into the bursa and causing an inflammation. The inflammation leads to swelling and thickening of the bursa's walls. This may remain even after the swelling goes away.

A local infection from a fall can cause bursitis too: the bacteria may travel to the bursa, get into fluid and cause an inflammation.

Knee anatomy - prepatellar bursa.
Knee anatomy - prepatellar bursa.

How do you treat knee bursitis?

Resting, icing the knee, and using elevation works well for knee bursitis.

The complete RICE protocol (Rest, Ice, Compression, Elevation) is not recommended as compression could be both painful and harmful.

It's also important to avoid whatever caused the bursitis to develop, so do not kneel down!

Anti inflammatory medication such as NSAIDs are good at reducing the inflammation.

If infection is behind the bursitis, your doctor may prescribe antibiotics to kill the bacteria.

In the end if nothing works out your doctor may opt to remove the bursa with a surgery.

Preventing recurrence of the bursitis

To prevent the swelling use knee pads for your work or for the sport that caused the injury.

Have rests and stretch your legs so your knees get some time for regeneration.

Avoid squatting if possible as squatting a lot can cause the bursa to get overloaded.

Lose weight if you are overweight. This will reduce the load on your knees and will prevent further strain and sprain.

Healthy mensicus and tear variations.
Healthy mensicus and tear variations.

Other cause #2: Torn meniscus

The menisci are C-shaped cartilages in the knee. They sit right between the shin and thigh bone, and help distribute the load evenly. Meniscus can tear from a sudden trauma or from slow degeneration.

The menisci has a rubbery texture, it's made of fibrocartilage. It also contains collagen fibers which help in maintaining it's shape.

There is almost no blood supply in the menisci which means that it can't really heal by itself.

When a meniscus tears, it can lock the knee as it gets caught inside of the joint. This is usually fixed with a quick operation, the torn part simply gets remove from the knee.

You can easily tear your menisci during everyday activities, nothing special is needed for this injury. Using your knees when you get in or out of your car, twisting your knee, squatting or skiing can all lead to a torn meniscus. These kind of traumatic tears often happen if you are between 10-45 years old.

Above 40 years of age the tear usually happens from degeneration of the menisci. In degenerative teary the tissue often separates horizontally but stays in place, so it rarely causes issues. Smoking is a risk factor for degenerative tears.

A torn meniscus is not always painful, and you may not even feel pain where your knee starts swelling.

If you feel pain, it will be worse during twisting and squatting. In the long term, the pain and swelling may even decrease by themselves, however this can take up to two months. Heavy activity will produce the knee pain again. If you've torn your medial meniscus, you'll feel pain on the inner side of your knee.

Front view of the knee, menisci are on the center left and right.
Front view of the knee, menisci are on the center left and right.

What are the long term complications of a torn meniscus?

In the long term, a torn meniscus can lead to excess joint fluid production. This in turn can lead to holding the knee in a bent position - there's more room for the fluid this way. Leaving your knees bent for long times will lead to the shortening of the hamstring muscles, so walking will get even harder.

As the torn part of the meniscus moves around in the knee joint while you are moving, it could damage the gliding surfaces of the knee. In the long term this can lead to painful bone-on-bone arthritis.

If the tearing is painful, this could keep you away from sports, which in turn could worsen your mood and overall quality of life.

How do you diagnose a torn meniscus?

The doctor can diagnose your torn meniscus looking at the swelling, loss of motion. X-ray and MRI are used to determine the exact cause. These are important as different knee injuries which need different treatment can have the same symptoms.

How do you treat a torn meniscus?

In the short term, a torn meniscus is treated with the usual combination of resting the knee, icing it, elevating it to let the fluid drain and taking NSAIDs to lessen the inflammation an the pain.

In the long term, if the torn meniscus locks the knee or produces swelling it can be removed through a small incision. Once the knee heels, you'll be able to use your knee just as before.

If the injury produces no pain, swelling or locking then there's probably no need for an operation.

A precise diagnosis is important, as a fragment of arthritic cartilage or small piece of bone broken inside the knee joint can create similar symptoms.

If you have a meniscal tear due to a degenerated meniscus, it may resolve by itself in a few months. These kind of tears often go together with osteoarthritis.

During the healing time it's important that you avoid the twisting motions which lead to the tearing most often. Strengthening the front thigh muscles with quarter-squats can help prevent further knee pain and keep the muscle from wasting. If you can't do even quarter squats from the pain, try flexing the quad muscle without moving your knee.

Using a knee brace or sleeve is beneficial, as it can take some load off your knees and make you feel more secure, check our Mava sleeve review and FitXpert sleeve review articles.

If you have arthritis too, treating the meniscal tear will only relieve the symptoms caused by the tear. The symptoms from arthritis - stiff, aching knees - will persist.

What other causes are there for a swollen knee with no pain?

A swollen knee can have many more causes, including infection, cysts, tumors. Make sure you go to the doctor ASAP with your knee problem - the earlier it's diagnosed, the faster the recovery will be.

To find out even more check Wikipedia's article on knee effusion, this one has many links for further research. Mayo Clinic has a concise article too which is great to get a quick overview.