Dealing with Knee Swelling and Tightness: Causes and Remedies!

What are the causes of a swollen knee that does not bend well?

In the vast majority of cases, a swollen knee is due to an accumulation of fluid in the knee joint. This fluid can be of two types:

🩸 Blood, known as hemarthrosis. It is often the result of an accident or contusion (impact).
💧Synovial fluid, called synovitis or synovial effusion, which is normally present in all joints to facilitate movement. However, it can be produced in excessive amounts, leading to joint swelling.

When there is an injury or inflammation, the blood vessels can become more permeable, allowing fluids to leak out of the vessels and accumulate in the joint, causing swelling.

Swollen knee due to impact, fall, or accident

Have you bumped your knee? Did you twist your knee while playing sports, slipping, or falling?

The most common causes of knee swelling in such cases are:

1. A bruise or hematoma, where certain blood vessels are ruptured.
2. A meniscal (meniscus) or cartilage injury.
3. A knee sprain, where one or more ligaments (internal or external ligaments, or cruciate ligaments) are stretched or torn.
4. A fracture of the patella, femur, tibia, or fibula.

To diagnose the issue, a doctor or physiotherapist will ask you questions and conduct an examination. In some cases, additional tests such as an X-ray, CT scan, or MRI may be necessary.

Swollen knee following surgery

Any surgery performed under local or general anesthesia at the knee level can cause swelling. Some examples include:

1. Knee Arthroscopy or a simple infiltration (not considered a major surgery).
2. Anterior cruciate ligament (ACL) reconstruction surgery.
3. Tibial tuberosity anteriorization (TTA) procedure.
4. Knee replacement surgery (see my article on edema after knee replacement).
5. Meniscus surgery.

Swollen knee without any apparent reason

If your knee is swelling without any evident cause, such as an injury, accident, or surgical intervention, there are several possible reasons for this swelling.

One possible cause could be a tendinopathy or tendonitis, which means that one or more muscle tendons that insert into the knee joint are inflamed. This phenomenon is usually related to overuse or repetitive movements. Some of the most common knee tendinopathies include:

• Patellar tendonitis
• Pes anserine tendinitis
• Iliotibial band syndrome
• Quadriceps tendonitis

Other potential causes of knee swelling include:

• Patellofemoral syndrome
• CRPS of the knee
• Bursitis
• Infection
• Gout
• Allergy
• Osteoarthritis or arthritis
• Popliteal cyst (which may feel like a lump behind the knee)
• Edema due to poor circulation of venous origin
• Edema of lymphatic origin
• Edema of cardiac origin
• In extremely rare cases, a tumor

The most common causes of knee swelling are injuries, surgeries, and edema related to venous return issues.

Why does a swollen knee often have difficulty bending?

When a knee is swollen, it can lead to difficulties in bending the leg.

This situation is common because the accumulation of fluid in the knee joint puts increased pressure on the surrounding tissues, such as muscles and ligaments.

When attempting to bend the knee, these muscles or ligaments have trouble stretching as much as usual, causing discomfort during flexion.

The swelling can also interfere with the nerve signals sent to the knee muscles, leading to a decrease in their strength and ability to contract.

There may also be inflammation of the synovial membrane that covers the knee joint, known as synovitis. This inflammation can cause additional pain and stiffness, making knee bending even more challenging.

In some cases, synovitis can also reduce the amount of synovial fluid in the joint, leading to a decrease in the necessary lubrication to facilitate movements.

Underlying causes of knee swelling can also contribute to difficulties in bending the leg. For example:

• Knee injuries, such as a sprain or tear of the cruciate ligament.
• Inflammatory diseases such as rheumatoid arthritis.

What can be done to improve knee bending despite the swelling?

Firstly, it’s important to know that a highly swollen knee will inevitably be limited in flexion, regardless of your efforts.

When your knee is swollen, the best approach is simply to maintain your current level of flexion. This can be achieved by:

• Remaining naturally active in your daily life: walking, going up and down stairs, cycling, driving, alternating between sitting and standing.
• Performing some specific knee flexion exercises in various positions. This can improve your comfort and alleviate pain:
  • Lying on your stomach, try to bend the knee as much as possible.
  • Sitting on a chair, bring the foot as far back as possible to flex the knee. If necessary, use the other leg to push the foot further back.
  • Assume a lunge position, place the foot on a step, hands against a wall, and bend the knee as much as possible.

Physical therapy for knee bending?

If you are undergoing physical therapy at home, in a clinic, or at a rehabilitation center, your therapist can also:

• Mobilize your knee to improve flexion.
• Use a machine such as an arthromotor (a device that helps flex the knee automatically, also known as Kinétek) or other equipment.
• Demonstrate more personalized exercises tailored to your current level.
• Above all, address your questions and provide reassurance.

It’s up to you to identify which approach is most suitable for you!

Surgery for knee bending?

In some cases, surgeons may also propose what is known as a knee manipulation, performed under general anesthesia, spinal anesthesia, or regional anesthesia. This involves manually forcing the knee into flexion while you are asleep or numb, in an attempt to “break” or “release” adhesions.

This procedure is typically offered at a considerable time interval after a traumatic event or knee surgery (generally several months).

Following this procedure, it is crucial to be diligent in maintaining the potential flexion gained. However, it may trigger knee inflammation again (to repair the tissues damaged by the knee manipulation).

This procedure is also often referred to as “manipulation under anesthesia” or “knee manipulation under anesthesia,” with AG standing for general anesthesia. It is also known as knee arthrolysis procedure.

Can reducing knee swelling help improve its flexibility?

Certainly, a less swollen knee is less likely to have difficulty in bending.

However, there is no guarantee of finding a solution that will immediately reduce knee swelling. The inflammation causing the swelling is often necessary for repairing the injured area.

As long as the area is injured, the inflammation and swelling may persist, regardless of what is done.

There is a near-infinite number of treatments or home remedies suggested for combating knee edema. Some of these are evaluated in clinical studies on healthy adults or in the context of specific pathologies, while others are not.

List of treatments often suggested for knee edema

This list proposes several treatments sometimes recommended to alleviate knee swelling. These include:

• Wearing compression stockings (see on Amazon)
• Applying cold packs
• Undergoing pressotherapy or lymphatic drainage sessions
• Using shockwave therapy or ultrasound therapy
• Wearing a brace or orthosis
• Elevating the leg (with the foot higher than the heart)
• Avoiding prolonged standing
• Walking as much as possible
• Taking anti-inflammatory medications
• Modifying one’s diet (particularly reducing salt intake)
• Undergoing aspiration or infiltration
• Using essential oils

Which treatment is most likely to be effective for a swollen and stiff knee? Here’s my perspective.

My recommendation as a physiotherapist for knee swelling

To choose the most appropriate treatment, I recommend considering four criteria:

1. Theoretical and empirical effectiveness
2. Side effects
3. Cost (in terms of money and time)
4. Dependence on a third party or equipment.

❌ For example, I automatically rule out surgical procedures like aspiration, as there is no long-term guarantee that the fluid will not return to the joint, and it can be costly to implement with a risk of side effects like infection.

❌ I also exclude shockwave therapy since the theoretical mechanism of action on edema is not very coherent, and it requires visiting a equipped professional or investing in expensive equipment.

How long does it take for a swollen knee to bend properly?

Even with a very precise assessment of your health condition, medical history, and current limitations in knee flexion, it is very difficult to provide an exact prognosis for the recovery duration.

Some people, following an injury, may have significant difficulty bending their knee for a few days. However, as the swelling reduces and the pain subsides, they may regain almost full flexion within a few days.

On the other hand, some people with a similar injury mechanism may take several months to achieve the same level of knee flexion as before.

So, how long does it take for a swollen knee to bend properly? In the best-case scenario, it may take a few days, more commonly a few weeks, and sometimes several months or even years.