Swollen Knee

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The knee is a hinge joint that is responsible for weight-bearing and movement. It consists of bones, meniscus, ligaments, and tendons. The knee is fully designed to fulfill various amounts of functions, including the following:

  • Provide enough stability.
  • Helps to lower and raise your body.
  • Allows twisting of the leg.
  • Makes walking much more efficient.
  • Supports the body in an upright position without the need for muscles to function.

A swollen knee (also known as “Water on the Knee”) occurs when an excessive amount of fluid accumulates in or around your knee joint. Your doctor might refer to this condition as an effusion in your knee joint. A swollen knee may be the result of trauma, overuse injuries, or an underlying disease or condition. In order to determine the cause of the swelling, your doctor may need to obtain a sample of the fluid to test for infection, disease, or injury. Swelling in a knee joint may also limit knee flexibility and function. For instance, a person may find it difficult to completely bend or fully straighten a swollen knee, and the joint may naturally bend 15-25 degrees while the leg is at rest. The swollen knee may also appear red, thus leading to the difficulty of bearing weight on it.

Whether water on the knee is mildly 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 normally recommended.

Causes & Symptoms

If the knee joint is the area of effusion, the following causes are possibly related to the main cause of knee swelling.


Acute injuries

Acute injuries are those that have occurred within the past 24 to 48 hours, resulting in rapid swelling of the knee. Acute knee injuries are determined whether the fluid in the knee is bloody or non-bloody, as described below:

  • Blood in the knee fluid – This is typically caused by either a torn anterior cruciate ligament (ACL) in the knee or a fracture of the bone and cartilage of the knee. When the bleeding is the source of the swelling, the onset will be rapid and intense, usually within minutes.
  • Non-bloody fluid – This type of knee fluid can be caused by a ligament sprain or a meniscus tear in the rubbery disk that cushions the knee. The swelling is normally slower and often only noticeable hours or days after the injury.


Chronic effusions

Chronic effusions are characterized by the gradual onset of swelling. The swelling can commonly fluctuate as the symptoms come and go. In addition to aging-related wear-and-tear, there are two common causes for a chronic knee effusion, such as:

  • Osteoarthritis – can cause an abnormal amount of fluid production in response to underlying inflammation. With knee osteoarthritis, the affected knee is often larger than the other. Swelling tends to worsen with activity, particularly when the knee bears weight. The pain will often disappear once the knee is relaxed.
  • Rheumatoid arthritis – an autoimmune form of arthritis, can cause the exact same effect. Rheumatoid arthritis will most likely affect several joints accompanied by a greater persistence of swelling due to the ongoing, underlying inflammation.


Throughout symptoms associated with a swollen knee, there are different types of inflammation that plays a role with this injury. In the joints, such as the knee, a person may have:

  • Swelling inside the joint (effusion).
  • Swelling in tissues around the joint (edema).
  • Swelling and a buildup of blood within the joint (hemarthrosis).


Inflammation, and therefore swelling, can be acute or chronic. Acute swelling may result from an injury and disappear within a day. Chronic swelling can last much longer and indicate an underlying medical condition. The four key signs of acute inflammation include:

  • Pain
  • Complete or partial loss of function
  • Heat
  • Redness

Who gets a Swollen Knee?

Some risk factors linked to a swollen knee include aging, sports, and weight problems, such as described below:

  • Age – Your likelihood of developing a swollen knee related to arthritis increases as you age. This is due to the general wear and tear of your bones.
  • Sports – Athletes who participate in sports that involve twisting the knee, such as basketball, are more likely to experience the types of knee injuries that cause swelling.
  • Obesity – Excess weight puts added stress on the knee joint, contributing to the tissue and joint overload and knee degeneration that can lead to a swollen knee. Obesity increases your risk of osteoarthritis, one of the more frequent causes of knee swelling.

How Does it Affect You? How Serious is it?

Several complications can occur alongside a knee swelling, from septic bursitis to developing gout or pseudogout. Below is an in-depth explanation of each complication accompanied by a severe swollen knee.


Bursitis (septic or non-septic)

Throughout the body are tiny, thin, fluid-filled sacs called bursae. These cushions help reduce friction between bone and surrounding soft tissue, such as skin and muscle. The knee has a total of 11 bursae, and 2 of them are susceptible to bursitis. Therefore, when a bursa becomes inflamed, it is called bursitis. An inflamed knee bursa can fill with excess fluid, causing swelling, or water on the knee. Furthermore, the swollen knee may feel “squishy”, like a water balloon. It may or may not be tender and painful. The most common types of knee bursitis are prepatellar bursitis and pes anserine bursitis.


A painful accumulation of microscopic uric acid crystals in the joint defines a gout attack. This swelling often occurs at night, while lying in bed. It usually occurs quickly and is associated with a sudden, excruciating pain, redness, and warmth.


Pseudogout is also caused by an accumulation of microscopic crystals in a joint. Calcium pyrophosphate crystals can accumulate in a knee joint and cause sudden, severe pain, and swelling. The skin over the affected joint may appear discovered. Additionally, pseudogout occurs most frequently in the knee and can also affect the shoulder, elbow, ankle, wrist, large knuckles, hip, or spine. It may affect more than one joint at a time and may be mistaken for rheumatoid arthritis or osteoarthritis.

Recommended Treatment & Rehabilitation

During a diagnosis of a swollen knee, your doctor will begin by asking you questions about your knee pain, such as the location of your pain, the severity of your knee injury, and its range of motion. Along with these questions your doctor will perform a physical exam to further examine your knee and afterward suggest the next step in terms of diagnosing the problem. You may have a blood test or fluid taken from the knee with a needle for lab examination.

A physiotherapist will then develop a personalized rehabilitation program for your swollen knee. Some general treatment techniques may include:


Pain management

Your physiotherapist will design a program to address your pain that includes applying ice to the affected knee. They may also recommend modifying some activities that cause pain. Your physiotherapist will then use and teach you pain-management techniques to help reduce or eliminate the need for medication.

Supporting equipment

Depending on your condition, your physiotherapist or healthcare providers may recommend braces, walking aids, wraps, or tape. A cane, walker, or crutches can help reduce your knee pain and improve your ability to walk regularly. Your physiotherapist may also recommend that you use these walking aids for a short period of time. He or she may also recommend a brace to stabilize your knee during the initial recovery phase. Wrapping your knee to reduce swelling can also be recommended.

Range-of-motion exercises

If the mobility of your knee is limited, it can cause increased stress on your knee. Lack of movement in your hip, foot, or ankle also may be forcing your knee to work at a disadvantage. Your physiotherapist may teach you stretching techniques to decrease tension and help restore the normal motion of your joints.

Manual therapy

Your physiotherapist may treat your sprained knee by applying hands-on treatments to gently move your muscles and joints. These techniques help to restore and improve proper motion. They also may be used to guide your joints into a less stressful movement pattern.


Strengthening the muscles around your knees and hips will ease the stress on your knees. These exercises help correct problems with alignment and muscle balance around your knees. The following exercise examples include the following below:


Hamstring stretch

Lie on your back with one leg fully extended. Next, with your other leg, wrap your hands around your thigh and slowly straighten your knee until you feel a stretch in the back of your thigh. Try getting the bottom of your foot to face the ceiling. Hold this stretch for 20 seconds, then repeat 3 times a day.


Calf stretch

Face the wall, standing about 2 feet away, and place your hands against the wall. Step forward with one foot and keep the knee bent slightly. Next, keep both heels on the ground, while leaning your hips towards the wall. Keep your back leg straight to stretch your calf muscle. Finally, hold this stretch for 20 seconds, then repeat 3 times a day.


Wall slide

Begin by standing with your heels about 6 inches away from a wall and your feet about a foot apart. Your back and buttock should be pressed against the wall. Slowly slide your hips down the wall until your knees are bent at roughly a 45-degree angle. Hold that position for about 5 seconds, and then slowly slide back up to the starting position. Repeat this motion 10-15 times for 2-3 sets a day.

Alternative & Homeopathic Treatment

Depending on the type and severity of your swollen knee problem, homeopathic treatments can strongly help you improve any mild symptom associated with this condition. Some of these treatments include:


  • I.C.E. – Rest, icing, compression, and elevation may be advised to help reduce the initial symptoms of runner’s knee. This protocol will be particularly important if the symptoms are manifesting for the first time.


  • Non-steroidal anti-inflammatory drugs (NSAIDs) – Over-the-counter or prescribed anti-inflammatory medications can help reduce inflammation and swelling due to your knee injury.


  • Shoe inserts – Wearing shoe inserts may benefit a subset of individuals with abnormal foot structure or movement patterns while running.


  • Ginger or turmeric – Both herbs are known for their anti-inflammatory properties. Moreover, some studies have found them to be comparable in effectiveness to ibuprofen, a commonly used NSAID.

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