Reflex arthritis

When they are young, many people do not pay much attention to the health of their joints and bones, thinking that their bodies are in relatively good condition. Even in the coldest seasons, there are many people who love beauty and wear very thin clothes. Not only are they prone to symptoms of colds and fevers, but their joints are also prone to inflammation over time, leading to symptoms such as arthritis and gout when they are older. Reflex arthritis is a type of arthritis. What symptoms will patients with reflex arthritis experience?

Reactive arthritis (ReA) refers to acute non-septic arthritis secondary to infection elsewhere in the body. ReA is most common after intestinal or genitourinary tract infection.

Clinical manifestations

1. Systemic symptoms Most patients have a history of precursor infection within 1 month before the onset of the disease, such as venereal urethritis or bacterial enteritis. The onset is generally acute, with symptoms such as fever (usually moderate to high), weight loss, fatigue, weakness, and sweating. Fever usually lasts 10 to 40 days and resolves spontaneously.

2 Musculoskeletal manifestations

1) All patients with peripheral arthritis have joint symptoms, and acute arthritis is the most common initial symptom. Typical arthritis occurs 1 to 4 weeks after urinary tract or intestinal infection. It is usually monoarthritis or oligoarthritis with asymmetric distribution. The knees, ankles and metatarsophalangeal joints are most commonly affected, and small joints, upper limb joints and hip joints may also be affected. Affected joints present with severe pain, swelling, warmth, and tenderness. The knee joint is often swollen and has a large amount of fluid accumulation, and may even be accompanied by a popliteal cyst (Baker cyst). Arthritis usually lasts for 1 to 3 months, and in some cases it can last for more than half a year. Some patients may develop joint deformities and ankylosis during repeated attacks.

2) Local tendinopathy Local tendinopathy is a unique joint lesion in RS. 42% of patients have pain limited to the tendon attachment point, either alone or in combination with arthritis. Inflammation usually occurs at the tendon's attachment to the bone rather than in the synovium (although synovitis may be present). The classic manifestation of tendinopathy is inflammation of the Achilles tendon enthesitis, followed by inflammation of the plantar fascia at the attachment of the calcaneus, and may also affect the ligaments around the ankle and subtalar joint, which is called painful heel syndrome. In the fingers and toes, the entire finger/toe is swollen (Sausage digit), which has diagnostic value.

3) Pelvic and axial lesions Joint stiffness, myalgia and low back pain are prominent symptoms in the early stages of the disease. Back discomfort often radiates to the buttocks and thighs and is aggravated by bed rest and inactivity. Inflammatory back pain or low back pain or buttock pain is a highly distinctive symptom, often due to sacroiliitis, and is often unilateral or asymmetric. The spine may be significantly affected in patients with severe, chronic or recurrent disease.

Test diagnosis

The diagnosis of reactive arthritis mainly relies on clinical symptoms and imaging manifestations, and laboratory tests can provide auxiliary diagnosis. In the acute phase of reactive arthritis, the white blood cell count often increases, the erythrocyte sedimentation rate accelerates, and the CRP increases. The patient's immunoglobulins, especially IgA, will increase, and complement C3 and C4 will increase. In some cases of patients with reactive arthritis, ASO may be positive.

【Related inspection items】

1. HLA-B27 About 70% of patients with reactive arthritis are positive for HLA-B27. Such patients are prone to ankylosing spondylitis. If ankylosing spondylitis is caused by reactive arthritis, the patient's rheumatoid factor is negative. The second is 1339, and B61, B7, B22, B40, B60, etc. that cross-react with B27 will also test positive.

2. Antinuclear antibodies in patients with antinuclear antibody reactive arthritis may be positive.

3. Urinalysis Most patients with reactive arthritis will show proteinuria in urine routine tests, and the urine protein content is generally below 1g/d.

4. The RF of patients with rheumatoid factor-responsive arthritis is generally negative, which can be distinguished from rheumatoid arthritis.

5. Other patients with reactive arthritis can also undergo throat swab culture and joint fluid culture. Throat swab cultures of some cases of reactive arthritis often show growth of streptococci. Such patients are ASO positive. In the joint fluid culture, the test result of patients with reactive arthritis is generally negative, but extremely low-activity chlamydia or its bacterial component DNA or antigens can be detected in their sediment or synovium; the chlamydia culture of feces or other excretions of patients in the acute phase is positive. Such patients often have positive anti-Chlamydia antibodies.