Rheumatoid arthritis of knee: Overview and Causes

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OVERVIEW

Rheumatoid arthritis of knee is a common form of inflammatory arthritis that occurs throughout the world and in all ethnic groups. It is a chronic disease with periods of flares and periods of remission.

According to the CDC, women are two to three times more likely than men to have rheumatoid arthritis (RA), and risk is highest in adults aged 50 to 59.

Causes Of Rheumatoid Arthritis Or Knee

Both environmental and genetic factors play a part.

• More common when an identical twin also has RA
• Genetic predisposition: certain genes raise the risk
• Variations in the HLA class II genes
• Infections may help trigger the autoimmune process in some people, though this is not proven.
• Increased risk with cigarette smoking, which can also make the disease worse
• Symptoms often ease during pregnancy, likely because of immune and hormonal changes, and may flare after delivery.

Pathogenesis of Rheumatoid Arthritis of Knee

Rheumatoid arthritis of knee is an autoimmune condition in which the body’s immune system attacks the body's own tissue. Immune cells, including T cells and B cells, play an important role in rheumatoid arthritis. They cause long-term inflammation of the synovium, the inner lining of the joint.

The inflamed tissue releases chemicals such as prostaglandins and nitric oxide. These widen blood vessels and cause swelling and pain.

At the joint margins, the inflamed synovium thickens and invades cartilage and bone, causing bone erosions. Without timely treatment, this damage can progress and lead to joint deformity and loss of movement. RA can also affect organs outside the joints, such as the lungs, heart, and eyes.

Clinical Features Associated With Rheumatoid Arthritis:

• Knee joint

Rheumatoid arthritis usually starts in small joints but often affects large joints such as the knees and ankles. Knee pain may worsen with bending, walking, running, and climbing stairs.

Morning stiffness usually lasts longer than 30 minutes and improves with activity during the day. Some people develop a fluid-filled cyst behind the knee (a Baker's cyst), where synovial fluid collects.

This cyst can rupture, causing pain and swelling in the calf. There is no cure for RA, but early treatment and taking medicines as prescribed can control inflammation and protect the joint.

• Joint Involvement

The typical presentation is pain, swelling, and stiffness in the small joints of the hands and feet. RA usually affects joints in a symmetrical pattern, so if one knee is affected, the other often is too. Large joint involvement, whole-body symptoms, and features outside the joints may also occur.

In older adults, RA can start suddenly with severe pain, morning stiffness, and many affected joints. Its symptoms can sometimes resemble polymyalgia rheumatica, which causes pain and stiffness in the shoulders and hips.

Long-standing disease can cause hand deformities, including ulnar deviation (fingers drifting toward the little finger), swan neck deformity, buttonhole deformity, and Z deformity of the thumb.

• Rheumatoid Nodules

Rheumatoid nodules are firm lumps under the skin. They are often painless but can sometimes become infected or ulcerated.

In weight-bearing joints, the bursa can become inflamed, and a knock-knee (valgus) deformity may develop. Damage to the ankle and foot joints can lead to flat feet.

• Systemic features

Rheumatoid arthritis is associated with whole-body features such as fatigue, weight loss, loss of appetite, osteoporosis, and muscle wasting. Long-standing disease can affect organs outside the joints.

• Extra articular disease

It may cause vasculitis (inflammation of blood vessels), skin ulcers, and tissue damage. Eye involvement can cause dryness, pain, and redness.

RA raises the risk of heart disease and can inflame the sac around the heart. Lung inflammation and scarring, nerve problems, spinal cord compression in the neck, and anemia may also occur.

How to Diagnose Rheumatoid Arthritis of Knee?

• Clinical criteria
• Erythrocyte Sedimentation rate
• C reactive protein
• ultrasound of knee joints
• MRI of knee joints
• Rheumatoid factor
• Anti-citrullinated protein antibodies (anti-CCP)
• X-ray of knee joint

Tests to monitor drug safety

• urinalysis
• full blood count
• urea, creatinine
• liver function tests
• chest X-ray

How to Treat?

The goal of treatment is to reduce joint inflammation, prevent joint damage, and improve mobility. A rheumatologist usually combines medicines with exercise and other lifestyle measures.

• Disease modifying anti rheumatic drugs (DMARDS): DMARDs are the main treatment for RA. They may slow the disease, control joint swelling, and help prevent deformity. Methotrexate is usually the first choice, sometimes with a short course of a steroid such as prednisolone. If it does not work well enough, another DMARD may be added.
• Triple therapy: One combination option is methotrexate, sulfasalazine, and hydroxychloroquine.
• Biological therapy: If the disease stays active despite standard DMARDs, a doctor may prescribe a biologic, a type of DMARD that blocks specific parts of the immune system.
• Conservative management: Stay physically active, keep a healthy weight, quit smoking, avoid repetitive joint strain, treat infections promptly, and do aerobic and strength training exercises.
• Surgical management: If the knee is badly damaged and treatment no longer controls pain or mobility, knee replacement surgery may be an option.

Complications of Rheumatoid Arthritis of Knee

Rheumatoid arthritis of the knee is a chronic disease that often involves several joints. It is associated with a wide range of complications, some of which are:

• difficulty in walking
• Immobilization
• difficulty in climbing stairs
• difficulty in bending of legs
• cysts behind knee joint
• inflammation of cyst
• infection and bursting of cyst
• chronic pain
• anxiety and depression in patients due to the chronic course of the disease

When to Seek Medical Help?

See a doctor if you have knee pain, swelling, or morning stiffness that lasts more than 30 minutes and keeps coming back, especially if other joints are affected. Early diagnosis and treatment can help prevent joint damage and complications.

HP Thoughts: Continue reading regarding joint pains: Osteoarthritis Treatment.

Sources

• Rheumatoid Arthritis, CDC
• Rheumatoid Arthritis Symptoms, Causes, & Risk Factors, NIAMS