What Are The Causes Of A Popliteal Cyst
Synovial fluid is a clear liquid that normally circulates through the cavities in your knee joint. Sometimes the knee produces too much of this fluid. The increasing pressure forces the fluid to the back of the knee via a one-way valve, where it creates a bulge. This severe swelling of the knee causes a popliteal cyst to form.
The most common causes of a popliteal cyst are:
- damage to the knees cartilage
- arthritis of the knee
- rheumatoid arthritis
- other knee conditions that cause joint inflammation
Since the knee is a complicated joint, it can be injured easily. According to the American Academy of Orthopedic Surgeons , about 10.4 million Americans saw their doctors about a knee problem in 2010, making it the most common reason for seeing an orthopedic specialist. Such injuries may cause the inflammation that leads to a popliteal cyst.
A blood clot can also cause bruising and swelling behind the knee and on the back of the calf. Its important that your doctor examines the swelling to determine if the cause is a cyst or a clot.
You may not feel any pain with a popliteal cyst. In some cases, you may not notice it at all. If you do experience symptoms, they might include:
- mild to severe pain
How Is Knee Pain On The Outside Of The Knee Diagnosed
When you see a doctor about lateral knee pain, theyll first ask you to describe the location and type of pain, for example is the pain sharp or aching? Theyll also ask you when the pain started and what activity you were doing when your symptoms began.
Theyll then perform a physical examination that will typically involve extending and flexing your knee, as well as moving it gently from side to side. This may reveal whether theres any swelling, areas of tenderness, or looseness in any of the ligaments.
Imaging tests may also be appropriate, including one or more of the following:
- X-ray to see bones
- Magnetic resonance imaging to get detailed images of ligaments, tendons, muscles, and cartilage
- Computed tomography scan provides a more detailed image of the bone than is possible with a standard X-ray
Based on your symptoms, the physical exam and imaging, a doctor should be able to diagnose the cause and severity of your knee injury and propose a treatment plan.
For minor lateral knee injuries, rest and conservative measures are all that are needed to allow them to heal. However, ligament tears, meniscus tears, and advanced arthritis may require surgery.
What Causes Swelling Behind The Knee
There are a number of different causes of swelling behind the knee. In most cases, back of knee swelling is caused by a build-up of fluid or an abnormal growth in the popliteal space the soft area at the back of the knee.
Here we look at five common causes of swelling behind the knee, the causes and symptoms of each, how to tell whether its something serious and the best ways to treat causes of swelling behind the knee.
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What Can You Do For The Pain
The things you can do for your knee pain will depend on your knee pain and injury.
Sharp pain and dull pain will need different treatment plans, and traumatic injuries will need different treatments than slow, gradual knee pain.
Here are a few things you can do to accelerate the healing process:
- Rest your knee and take a few days off from intense activity.
- Ice it to curb pain and swelling.
- Compress your knee with an elastic bandage, straps, or sleeves to wrap the joint.
- Elevate your knee with a pillow under your heel when youre sitting or lying down
- Take anti-inflammatory medications. These drugs can have side effects, so dont use them long-term
- Practice stretching and strengthening exercises recommended by your doctor.
- Start physical therapy
Contact your doctor if you have tried home treatments for two weeks but still havent found relief.
If you get a fever along with your painful knee, go to the doctor right away.
Depending on the cause of your knee pain, you may need extra help from a doctor.
If you have bursitis, your doctor may need to draw out extra fluid from the bursa in your knee.
Or, if you have arthritis, you may need a corticosteroid shot to reduce inflammation.
Some Knee Joint Anatomy
The first diagram below illustrates a typical normal knee joint looking from the side.
The joint capsule is a thick structure that surrounds your whole knee and gives it some support. It is lined by a special membrane called the synovium. The synovium produces a fluid called synovial fluid. This fluid acts as a lubricant within your knee joint and helps to cushion it during movement.
There are also various tissue pouches called bursae next to the knee. A bursa is a small sac of synovial fluid with a thin lining. Bursae are normally found around joints and in places where ligaments and tendons pass over bones. They help to reduce friction and allow maximal range of motion around joints. The bursa at the back of your knee is called the popliteal bursa.
Each knee joint also contains a medial and a lateral meniscus. These are thick rubber-like pads of cartilage tissue. The menisci cartilage sit on top of, and are in addition to, the usual thin layer of cartilage which covers the top of one of the bones of the lower leg, called the tibia. They act as shock absorbers to absorb the impact of the upper leg on the lower leg. They also help to improve smooth movement and stability of the knee.
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Common Causes Of Pain Behind Knee
Where do we start with making an accurate diagnosis?
Generally, most doctors use a methodological process to confirm or rule out causes. Firstly, we perform a thorough assessment to test the joints, ligaments, and tendons that pass across the back of the knee. Then, we consider imaging to confirm our thinking. X-rays often pick up major arthritis in the knee. MRI can detect soft tissue problems such as tendonitis or muscle tear. Occasionally, we perform other tests such as blood, ultrasound, or nerve studies depending on the presentation.
Generally, the more common causes of pain behind the knee include:
Questions For Diagnosing The Cause Of Behind Knee Swelling
To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your behind knee swelling including:
How long have you felt your behind knee swelling?
Is the swelling painful?
Is the swelling the result of an injury?
Do you have any chest pain or ?
Do you have any symptoms in other joints?
Does anything relieve or worsen your symptoms?
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Key Points About Baker Cysts
- A Baker cyst is a fluid-filled sac that forms behind the knee. They usually don’t cause major problems.
- A Baker cyst is usually the result of some other problem with the knee. It may be caused by osteoarthritis or a tear of the knees cartilage.
- Many people with Baker cysts dont have any symptoms. You might have some pain behind the knee.
- Your healthcare provider will try to treat any underlying conditions. You may also need fluid removed from the knee joint space or the cyst.
- Surgery isn’t usually needed for a Baker cyst.
- In rare cases, a Baker cyst can rupture. This can cause serious complications. See your provider right away if your leg is red and swollen.
Potential Causes Of Knee Swelling
Whether water on the knee is mildly annoying or painfully debilitating, a person will want to identify the likely cause and treat the symptoms to help reduce the likelihood of future problems. Chronic or long-standing swelling may lead to joint tissue damage, cartilage degradation, and bone softening, therefore treatment is usually recommended.
This article describes 12 conditions that frequently cause knee swelling, also called water on the knee.
1. Injury to the kneeTrauma to the knee’s bones, ligaments, tendons, bursae, meniscus, or articular cartilage can cause pain and swelling. Serious injury can cause blood to flood into the knee joint, leading to significant swelling, warmth, stiffness, and bruising. This condition is called hemarthrosis and warrants urgent medical care.
A patient should also seek medical attention if knee pain is severe, if the affected leg cannot bear weight, or if there is suspicion of a broken bone.
2. Knee osteoarthritisDegeneration of the cartilage of the knee joint can result in an overproduction of joint fluid, causing the knee to swell. A swollen knee due to knee osteoarthritis is typically accompanied by pain.
In fact, evidence suggests people who have severe knee pain from osteoarthritis are more likely to experience knee swelling. One study2 found that:
People should seek medical attention immediately if they think their symptoms may be caused by septic bursitis.
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Symptoms Associated With Posterior Knee Pain
There are many different causes for pain at the back of your knee, with symptoms varying accordingly. Depending on the cause, symptoms include:
- A popping noise on injury
- Locking of your knee
- Sudden pain or muscle tightening at the back of your knee
- Stiffness and difficulty bending or straightening your leg
- Swelling, bruising, redness and/or warmth
- Weakness in your knee you may find it difficult to support your weight or stand on your tiptoes
Treatment Of Any Underlying Knee Problem
It is important that any underlying knee problem is treated if you have a Baker’s cyst. This may help to reduce the size of a Baker’s cyst and any swelling or pain that it causes. For example, if you have osteoarthritis, a steroid injection into the knee may help to relieve pain and inflammation. However, this does not always stop the cyst from coming back again.
If you have an injury to the knee such as a meniscal tear, treatment of this may help to treat the Baker’s cyst as well. See the separate leaflets called Knee Ligament Injuries and Meniscal Tears for more detail.
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How Is A Bakers Cyst Treated
Treatment of a Bakers cyst usually starts with nonsurgical options. One time-honored method that sports doctors and orthopaedic surgeons have relied on for decades to soothe swelling from joint damage is the RICE method: Rest, Ice, Compression, Elevation.
Often, your healthcare provider will suggest that you start with a nonsurgical treatment of your Bakers cyst. These are generally things you can do at home and on your own that can improve your symptoms.
Nonsurgical treatment options can include the RICE method:
- Resting your leg whenever possible.
- Applying ice to your knee.
- Using compression wraps on your knee to decrease the amount of joint swelling.
- Elevating your knee while you are resting.
Other nonsurgical treatment options for a Bakers cyst can include:
- Taking an anti-inflammatory medication, such as ibuprofen.
- Maintaining a healthy body weight, which can help put less pressure on your joints.
- Avoiding activities that strain your knee. This includes avoiding high-impact sports like jogging.
- Using a crutch or cane when you walk.
- Getting a referral for physical therapy from your healthcare provider to help strengthen your knee and body.
Your healthcare provider may also give you a steroid injection. This involves cortisone being injected into your knee joint, which can reduce inflammation and pain.
Your provider might suggest a surgical option to you if:
- Your knee pain is severe.
- Youre unable to move your knee well .
What Is A Baker’s Cyst
A Baker’s cyst is a fluid-filled swelling that can develop behind the knee. It is one cause of knee pain.
It is named after a doctor called William Baker who first described this condition in 1877. It is also sometimes called a popliteal cyst, as the medical term for the area behind your knee is the popliteal fossa.
The cyst can vary in size from a very small cyst to a large cyst that is a number of centimetres across. Rarely, a Baker’s cyst can develop behind both knees at the same time.
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How Is A Baker Cyst Diagnosed
Your healthcare provider will ask you about your medical history and your symptoms. They will give you a physical exam, which will include a careful exam of your knee. Its important to make sure your symptoms are caused by a Baker cyst and not a tumor or a blood clot.
If the cause of your symptoms isnt clear, you may have imaging tests, such as:
- Ultrasound, to view the cyst in more detail
- X-ray, to get more information about the bones of the joint
- MRI, if the diagnosis is still unclear after ultrasound or your provider is considering surgery
What You Can Do
Take over-the-counter NSAID drugs like ibuprofen and naproxen to ease pain and swelling. RICE — rest, ice, compression, and elevation — can often help, too: Get off your feet. Raise your leg so it’s higher than your heart. Put a cold pack in a thin cloth or towel on your knee for 10-20 minutes at a time, several times a day. Wrap an elastic bandage around your knee when you’re up and about, snug but not tight.
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How To Treat Swollen Legs From The Knee Down
There are many ways you can treat swollen legs from the knee down, depending on the underlying cause. Some of the most common at-home remedies include elevating your legs periodically, wearing compression stockings, regular exercise, monitoring salt intake, and maintaining a healthy weight.
In more serious cases, surgery is an option should the underlying cause be related to varicose veins, venous insufficiency, or lymphatic system deficiencies. Speak with your healthcare provider to determine the potential underlying cause.
Lateral Tibial Plateau Fracture
The tibial plateau is located at the top of the shin at the knee. A break on the outer or lateral part of the tibial plateau can cause considerable knee pain. A lateral tibial plateau fracture is often the result of a vehicle accident or a bad fall that impacts the outer knee directly.
If the bones are still aligned, surgery may not be required to treat the injury. If not, you may need surgery to place the affected bones in their proper position and secure them with screws or plates.
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Lateral Collateral Ligament Injury
The lateral collateral ligament is one of the four main ligaments of the knee. It connects the outer side of the femur and tibia and is primarily responsible for stabilizing the outer aspect of the knee.
An LCL injury is often the result of a blow to the inside part of the knee this causes the LCL to stretch beyond normal and can result in partial or complete tearing of the ligament.
Symptoms may include soreness on the outside of the knee, swelling, and stiffness. You may experience instability a feeling that the knee is unstable and going to buckle or give out.
32 million adults in the United States.
With aging, the cartilage that helps cushion the ends of bones in the knee joint can wear thin and eventually allow the bones to rub together. Pain, stiffness, and loss of joint movement can follow.
Some people have more significant wearing of the cartilage in the outer compartment of the knee joint and this can lead to lateral sided knee pain.
Pain Behind Knee And Calf Other Causes
The pain you feel behind your knee could be something simple, or it could be a very severe problem, but you wont know until you have it examined. An examination is still the safest way, but knowing how to treat any concern you have is a close second.
Here are more causes of any pain you may experience behind your knee and calf.
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When To See Your Gp
See your GP if you have a lump behind your knee that’s causing problems and does not clear up on its own. They’ll usually be able to diagnose a Baker’s cyst by examining the back of your knee and asking about your symptoms.
Your GP will ask you whether you have any associated health conditions, such as arthritis.
Tennis Leg Causing Muscle Pain And Swelling Behind The Knee
A condition called tennis leg can also cause pain in the back of your leg behind the knee.
Tennis leg is associated with damage to the gastrocnemius where damage to the muscle and the soleus muscle in the calf causes a buildup of fluid.
According to the journal Radiology Case Reports, tennis leg is often a result of sports injuries. Damage to the calf muscles can cause swelling and pain in the posterior knee.10
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Are There Any Complications That Can Develop
The most common complication of a Baker’s cyst is for it to split open . If this happens, the fluid from inside the cyst can leak out into your calf muscle. This can cause swelling of your calf. You may also develop itching and redness of the skin of your calf because of irritation caused by the fluid that leaks out from the cyst. About 1 or 2 in 20 Baker’s cysts are thought to rupture.
If a Baker’s cyst ruptures, it can be quite difficult to tell the difference between the ruptured cyst and a deep vein thrombosis in the leg. A DVT is a blood clot that forms in a leg vein. In these cases, it is important that investigations are carried out to exclude a DVT because it can be a serious condition that needs treatment. See the separate leaflet called Deep Vein Thrombosis for more detail.
Very rarely, a Baker’s cyst may become infected.