Knee Synovitis – Causes, Symptoms & Treatment


Swelling of the knee joint with stiffness and an appearance of a reddish hue could mean knee synovitis. This is usually considered as a chronic knee pain condition.

The condition is a result of the inflammation of the synovial membrane in the knee joint. This membrane functions to lubricate the joint for proper range of motion.

Synovial joints such as the knees, shoulders, and hip are covered in a synovial membrane, which secretes synovial fluid. The inflammation of this membrane can result in joint stiffness and pain. 

Usually, this condition is a result of an underlying cause such as arthritis or knee gout. Knee synovitis is also associated with knee injuries or cancer. Therefore, it is important to understand the causes and treatment therapies for the proper management of this condition. (1)

Conservative treatment options are usually known to offer relief from pain and inflammation. Managing the underlying cause can also avoid recurring synovitis episodes.

Function of Synovium

The synovium is the lining tissue of a joint containing sympathetic and sensory nerves. The soft tissue lines the spaces of diarthrodial joints, bursae, and tendon sheaths.

synovial fluid in the knee

The two regions of the synovial membrane include the intima (synovial lining) and the subintima (sublining).

The membranous structure’s internal lining consists of fibroblast-like and macrophage-like synoviocytes. In a normal synovium, the sublining contains scattered immune cells, fat cells, blood vessels, and fibroblasts.

The fibroblast-like synoviocytes present in the intimal lining are known to produce specialized enzymes, whose function is to synthesize lubricants like hyaluronic acid.

The synovium present in the knee produces lubricants for the joint and provides nutrients to the cartilage. (2)

What Causes Knee Synovitis?

Knee synovitis is an inflammatory condition of the synovial membrane. The inflammation results in pain and stiffness in the knee joint.

Inflammation of the knee joint could be due to an internal joint bleeding, which causes the blood vessels around the injured joint to thicken. Some of the causes for the condition include the following.

  • Knee overuse or repetitive actions
  • Repeated knee injuries or traumas
  • Untreated arthritis

The condition is usually a result of an underlying medical condition such as gout or rheumatoid arthritis. It is also associated with cancer.

The proper management of the condition involves an assessment of the cause and understanding the treatment options. (3)

Primary Conditions

A direct blow to the knee can cause knee injury and synovitis. Such injuries are common in sports such as football, volleyball, and skiing.

However, a substantial impact on a hard surface during day-to-day activities can also cause significant injury to the knee.

An inflammation of the knee post an injury could also mean more serious cartilage and ligament tears. It is important to use self-care treatment therapies and avoid stressing the knee post an injury.

Strenuous activities should be resumed only after pain-free knee motion is achieved.

Secondary Conditions

Knee synovitis is usually a result of an underlying medical condition such as rheumatoid arthritis or gout.

Rheumatoid arthritis is an autoimmune disease that makes the knee joints swollen and painful. Women are more susceptible to suffer from this condition. (4)

Gout is a lifestyle disease, which results in uric acid crystals in the knee joints. The condition can result in inflammation and pain in the knee.

When the synovitis is due to these underlying causes, it is important to identify the cause to treat the synovitis. More importantly, it is essential to manage the underlying cause as ignoring them could lead to serious effects on the knee joint.

Sign & Symptoms of Knee Synovitis

Knee synovitis is associated with swelling over the knee joint. If the condition is a result of a knee injury, the swelling might appear right after the incident.

In case of an underlying cause, the knee swelling could be gradual. The symptoms of knee synovitis include the following.

  • Persistent swelling for days
  • Knee joint appears red or pink
  • Tender or warm to touch
  • Joint stiffness
  • Limited mobility

The condition is usually diagnosed with a physical examination and medical history to assess the possibility of an underlying cause.

MRI scans are used to confirm the suspected cases of knee synovitis. Aspiration techniques to drain the fluid from the knee and sent for testing can also be used for confirmation. (1)

A more serious form of the condition is Pigmented Villonodular Synovitis (PVNS). This condition is characterized by an enlargement of the synovial membrane.

This enlargement of the membrane causes a benign tumor, which is usually noticed in the knee and hip joints. The condition can spread to other areas if not treated promptly.

A MRI scan and biopsy is often used to confirm the diagnosis. The signs of PVNS include the following.

  • Increased swelling
  • Gradual rise in pain
  • Catching or locking sensation of the knee joint
  • Intermittent swelling and pain

The treatment options include synovectomy to remove the tumor. (1)

Synovitis Knee Treatment

The treatment options for this condition depend on the cause. Knee synovitis as an independent ailment is not considered a serious condition and can be managed with conservative methods. However, such cases are rare.

As secondary synovitis cases are more common, the treatment of knee synovitis requires a diagnosis at the early stage to manage the underlying condition.

In case of a primary condition caused due to an injury, the following therapy options can be implemented.

  • Rest: Avoid stress on the knee post an injury. Rest the knee and resume activity once the pain and swelling subside.
  • Ice: Ice packs can be used to get relief from the inflammation and pain.
  • Compression: Compression bandages are known to promote healing and improve the recovery process.
  • Elevation: Keeping the injured knee elevated can reduce pain and inflammation.

In case of an underlying cause, the treatment options can incorporate the RICE technique and also include the following.

Medications: NSAIDs such as Ibuprofen are known to offer relief from knee pain. They are useful in cases of synovitis caused by arthritis.

In the acute stages of synovitis, heat therapy, manual therapy, gait training, and cold therapy are used to get relief from the pain and inflammation.

Following this, heat therapy and physical therapy can be used for improving range of motion.

Physical Therapy

Regular exercises to improve range of motion and improve muscle strength can reduce pain and stiffness.

Stretching exercises are recommended to restore full range of motion of the knee. Since obesity is a primary cause of knee ailments, it is important to ensure that certain lifestyle changes are implemented to reduce the weight and reduce the pressure on the knees.

Splints can also offer pain relief and protect the knee joint from further injury. (5)

Surgical Intervention

Other treatment options include synovectomy surgery. Surgical intervention is recommended when the other treatment options have failed to provide relief or when the condition is affecting the normal functioning of the knee.

Synovectomy is associated with the removing or destroying the synovial membrane. The damaging membrane can be removed with the use of radiation, chemicals, surgery or arthroscopic procedures.

The procedure is indicated in conditions such as recurrent hemarthrosis seen in hemophilia patients, benign neoplastic disorders such as osteochondromatosis, and chronic inflammatory arthritides such as rheumatoid arthritis.

Radionuclide Synovectomy: The low-level radiation of a radioactive substance, when injected into the joint, is used to melt away the inflamed synovium.

Arthroscopic Synovectomy: The surgery is performed to remove the inflamed part of the synovial membrane. The aim is to reduce potential joint destruction and bleeding. (6) (7)

The healing time for this condition depends on the cause of knee synovitis. Conservative methods such as self-care techniques and medication are able to offer relief from the pain and inflammation.

However, the presence of degenerative diseases such as rheumatoid arthritis needs a diagnosis at an early stage to avoid degradation of the knee joint. Such cases require a treatment technique that is designed for the underlying cause to get relief from the pain and inflammation. (8)

Who is at Risk?

Synovitis of the knee is an inflammatory condition of the knee joint. The condition is usually a result of degenerative joint diseases. In cases where it is seen as an independent ailment, it is a result of a knee injury.

Individuals with degenerative joint diseases such as arthritis and gout are more prone to suffer from knee synovitis. As obesity and lifestyle choices play an important role in knee ailments, obese individuals could have a higher chance to suffer from the condition.

The condition is also susceptible in athletes involved in sports such as football, volleyball, and skiing.

Any activity that involves the possibility of a direct blow to the knee can also cause knee synovitis. Therefore, day-to-day activities can also result in knee pain and inflammation.

Synovitis Knee Prevention

The prevention tips for the condition depend on the cause of the synovitis. For an independent synovitis, the measures include simple steps and a cautious outlook.

However, the presence of degenerative joint diseases involves lifestyle changes that can improve the situation gradually.

Proper Techniques for Sports & Exercises

Implementing a proper technique for exercise and sports can avoid most knee injuries. Also, proper equipment should be used to avoid excessive pressure on the knee.

Shoes for exercising should be chosen as per the activity to avoid knee injuries.

The intensity and duration of training should depend on an individual’s fitness level. Moving from a sedentary lifestyle to an active lifestyle should involve gradual changes. A sudden increase in activity can have damaging effects on the knee joint.

A warm-up and cool-down period are extremely important to keep the muscles flexible for exercising.

In sports activities that have a potential for tackles or direct blows, protective braces can support the knee and cushion it from injury.

In case of activities that involve repetitive kneeling, pads can be placed below the knee to avoid injuring the knee.

Lifestyle Changes for Secondary Synovitis

Precautionary measures for synovitis caused by an underlying medical condition can be prevented by proper management of the underlying condition.

A higher body weight is associated with more stress on the knee joint. Obese individuals are known to be more prone to suffer from knee ailments.

Weight loss can be achieved with a combination of a nutritional diet and regular exercise. An anti-inflammatory diet rich in leafy vegetables and nuts can also help control weight and offer relief from inflammation.

It is important for arthritis and gout sufferers to continue stretching their muscles to avoid loss of muscle strength. Strengthening and stretching exercises can improve the knee’s range of motion and help relieve the pain.

Knee inflammation can cause discomfort and affect the daily life of individuals. Synovitis is rarely a result of an injury and is more commonly associated with degenerative medical conditions.

Therefore, the early diagnosis of the condition is imperative for proper management of the condition. Diagnosis of knee synovitis is usually confirmed with an MRI scan and aspiration.

Aspiration is undertaken to check the fluid from the knee for clarity, viscosity, and presence of white blood cells.

A physical examination is carried out to rule out inflammation caused by other knee ailments.

Since synovitis is also indicated in cancer patients, it is necessary to not ignore the signs of the condition.

In independently caused synovitis, conservative methods can treat the inflammation and pain. However, in other cases, the condition needs certain lifestyle changes for the proper management of the underlying cause.

The first line of treatment should continue to be RICE principles, progressing to include heat therapy and physical therapy. The recovery period should be treated with caution as an excessive pressure on the knee joint at this time could aggravate the injury and delay the healing process.

Surgical intervention of the inflamed synovium is recommended if all treatment options have shown no success. Surgery is also necessary for individuals who report an effect of their mobility.




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