Causes of arthralgia Arthralgia is a common clinical symptom, most often seen in joint pain of the extremities, divided into acute arthralgia and chronic arthralgia. Acute arthralgia is the main symptom of acute joint lesions, and in acute inflammation the local skin is often swollen, flushed, feverish and limited movement. In addition to acute joint lesions, acute arthralgia can also be caused by acute inflammation of the periarticular tissues (e.g., bursitis, tenosynovitis, fibrous tissue inflammation). Acute arthralgia has a rapid onset and is almost always characterized by fever and acute inflammation of the joint, such as redness, swelling, heat, pain and functional impairment. Chronic arthralgia is often prolonged for months, years, or even decades. The clinical manifestations are mainly joint swelling and pain, deformity, and different degrees of joint dysfunction, and some patients eventually become disabled and lose their ability to work. Chronic joint disease can cause hyperplasia and thickening of the joint capsule, destruction of cartilage and bone, narrowing of the joint space, and osteophytes. When the disease is prolonged, long-term joint inactivity and neurotropic disorders occur, resulting in osteoporosis and significant muscle atrophy. In advanced cases, periarticular tissue and cartilage fibrosis and even ossification are seen, and the cartilage is completely destroyed, so that the opposite bone ends heal each other, causing joint ankylosis and loss of function. Because of the many causes of arthralgia and the similarity of clinical manifestations, it can cause difficulties in diagnosis and differential diagnosis. (A) Causes of arthralgia