Knee Synovitis: Inflammation of the Synovial Membrane
What is knee synovitis?
Knee synovitis is a secondary condition that generally develops due to another condition such as rheumatoid arthritis or gout, or due to an injury to the knee-joint or cancer. It refers to the inflammation of the synovial membrane, which lines and lubricated the knee-joint.
Pigmented villonodular synovitis (PVNS) is a more severe form of synovitis that typically affects the knee and hip joints. It results in an overgrowth of the synovial membrane, leading to a benign tumour.
What are the causes of the disorder?
All large joints of the body (knee, hip and shoulder) are synovial joints. These joints are surrounded by a synovial membrane, which covers the joint and lubricates it by secreting synovial fluid. This lining can become inflamed, resulting in pain and stiffness in the joint.
Synovitis may be caused due to a variety of reasons, including
- Infection (tuberculosis, septic arthritis)
- Joint trauma
- Allergic reaction
- Systemic autoimmune inflammatory diseases like rheumatoid arthritis
The disorder may remain confined to one joint; in this case the knee, or it may involve multiple joints that signal a chronic symptom of a general disease progression.
People who are at an increased risk of knee synovitis include:
- Individuals exposed to prolonged, repetitive motion of the knee.
- Athletes participating in intense sports that involves running, climbing and jumping.
- Though synovitis is not sex-specific, rheumatoid arthritis, which is characterised by inflammatory synovitis is thrice more common in women than in men. Also it is observed more often in individuals under the age of 15 and over the age of 55.
- PVNS occurs more in individuals aged between 20 and 50.
- Conditions like gout that lead to uric acid production also increases the risk to synovitis. Other conditions that decrease excretion of uric acid, like renal failure, hypertension and alcohol consumption may also be associated with synovitis.
What one needs to know about symptoms or signs?
Symptoms of knee synovitis include episodes of pain and swelling that comes and goes. Pain may worsen when the knee-joint locks or catches.
Which specialist should be consulted in case of signs and symptoms?
Those who suspect knee synovitis must consult a rheumatologist, a doctor who specialises in treatment of inflammatory arthritis.
What are the screening tests and investigations done to confirm or rule out the disorder?
Knee synovitis is diagnosed through the following:
- Physical pain – The patient is tested for passive and active range of motion and indications of pain, stiffness and any noticeable joint noises are noted. The muscles surrounding the knee-joint are tested for pain and weakness.
- Laboratory tests – Complete blood count, urine analysis and erythrocyte sedimentation rate (ESR) are carried out to determine inflammation.
- Imaging tests – An x-ray may indicate any erosion of the joint surface.
What treatment modalities are available for management of the disorder?
Treatment of knee synovitis includes:
Medication – Anti-inflammatory drugs and corticosteroid injections help alleviate pain and swelling.
- Immobilisation – Immobilisation of the knee in a splint provides support to the joint.
- Heat therapy – Once the initial pain and inflammation lessen, heat packs may be applied to reduce joint pain and stiffness. Ultrasound may be employed to produce heat from high frequency sound waves that penetrate deep into the synovial membrane and surrounding joint.
- Exercise – Passive stretching exercises help restore range of motion slowly and strengthen the surrounding muscles.
- Surgery – In severe cases, surgical removal of the synovia (synovectomy) may be required, along with removal of ligaments and other structures to access and remove the inflamed joint lining. The procedure may be performed using arthroscopy (using tiny lighted camera and small instruments inserted through it via small incisions), with laser therapy or by injecting selectively destructive chemicals (chemical ablation).
What are the known complications in management of the disorder?
Synovitis may recur if the synovium regrows post-surgical removal or chemical or laser ablation. This occurs in cases when the underlying disease that caused the synovitis initially recurs. Also, in chronic synovitis, the synovia may grow over the surface of the joint and destroy the cartilage.
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“Primary Inflammatory (Synovial) Disease of the Knee,” Rosenberg Cooley Metcalf, http://www.rcmclinic.com/patient-info/knee/diagnosis/59-knee-diagnosis/95-primary-inflammatory-disease-of-the-knee
“Synovitis,” Disability Guidelines, Reed Group, http://www.mdguidelines.com/synovitis
“Synovectomy for Rheumatoid Arthritis,” WebMD.com, http://www.webmd.com/rheumatoid-arthritis/synovectomy-for-rheumatoid-arthritis