M02.862

Clinical Causes: Previous bacterial infections, particularly gastrointestinal or genitourinary infections Triggers like Shigella, Salmonella, Yersinia, Chlamydia, or Campylobacter Genetic predisposition, such as the presence of the HLA-B27 gene Autoimmune responses where the immune system mistakenly attacks joint tissue Environmental factors that may contribute to immune dysregulation

Key Symptoms: Pain in the left knee that may worsen with movement Swelling and tenderness in the affected joint Warmth and redness around the joint area Stiffness, especially after periods of rest or in the morning Reduced range of motion due to swelling and pain Possible systemic symptoms like fever or fatigue if an underlying infection persists

Diagnosis Path: Diagnosis of reactive arthritis affecting the left knee involves a combination of medical history, physical examination, and laboratory tests. Healthcare providers may look for recent infections or other triggers. Tests often include joint fluid analysis, blood tests for inflammatory markers (like ESR and CRP), and specific tests for infections such as urine culture or stool studies. Imaging studies like X-rays can help rule out other joint conditions and assess joint damage.

Treatment Protocols: Management of reactive arthritis typically focuses on alleviating symptoms and addressing the underlying cause if identifiable. Common approaches include: - Nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation - Physical therapy exercises to maintain joint function and strength - Corticosteroids, either systemic or injected directly into the joint, for severe cases - Antibiotics if a bacterial infection is still active or suspected - Rest and joint protection measures to prevent further stress on the knee - Monitoring and managing any extra-articular symptoms or complications In most cases, symptoms improve with appropriate treatment, although some individuals may experience episodes of flare-ups.