Rheumatoid arthritis invades any movable joint. It presents with pain (worsened by activity), swelling and tenderness. The typical order of joint involvement is: hands and wrists, feet and ankles, elbows, shoulders, knees, neck, and hips. 1. Hands and wrists: Almost all patients with rheumatoid arthritis have involvement of the hands and wrists. These joints are the first to be involved and are the site of characteristic deformities in the late stages. A typical early feature is the poke-like appearance of the fingers due to swelling of the proximal interphalangeal joints (PIP), often accompanied by symmetric swelling of the metacarpophalangeal joints (MCP), especially swelling of the II and III metacarpophalangeal joints is very common, and the distal interphalangeal joints (DIP) are rarely involved. Soft tissue laxity can produce ulnar deviation of the fingers, often accompanied by palmar subluxation of the proximal phalanges; ulnar deviation of the metacarpophalangeal joints is often combined with radial deviation of the radial metacarpophalangeal joints, resulting in a “zigzag” deformation of the hand; in advanced patients, due to hyperextension of the PIP and flexion of the distal interphalangeal joints, a “swan In advanced patients, “swan neck” deformity may occur due to PIP hyperextension and distal interphalangeal joint flexion. These changes will result in a loss of hand strength. Wrist involvement is particularly common in Chinese rheumatoid arthritis, and painless swelling of the ulnar styloid process is one of the early signs of rheumatoid arthritis. Acute synovitis manifests as cystic soft tissue swelling on the dorsal side of the wrist. Synovial thickening and sheathing on the palmar side may compress the median nerve under the transverse ligament, causing “carpal tunnel syndrome”. It may also be accompanied by atrophy of the greater interphalangeal muscle. In advanced stages, the wrist becomes immobile due to fibrous ankylosis or bony ankylosis of the radial carpal, intercarpal and/or carpometacarpal joints, and the involvement of the distal radial ulnar joint often causes extreme impairment of anterior and posterior rotation movements. 2. Foot and ankle: Arthritis of the foot is common and may even precede lesions of the hand and wrist, but the ankle joint is rare in early and mild patients. Synovitis of the metatarsophalangeal (MTP) joint is most common, and the interphalangeal joint is rarely involved. Swelling and subluxation of the metatarsophalangeal joint cause pressure pain on both sides of the toe, metatarsal pain, metatarsal head subluxation, bunion, lateral toe deviation and claw-like foot deformity. Early rheumatoid arthritis is often the first erosive changes in the metatarsophalangeal joints, and radiological examination is particularly sensitive to erosive changes in the 4th and 5th metatarsophalangeal joints. Elbow: flexion contracture due to hyperplastic synovitis of the elbow can be seen early in the disease, and a mass can form behind the lateral epicondyle of the humerus, proximal to the radial head, and the pars plana sulcus is often flooded by hypertrophic synovium. 4. Shoulder: Shoulder joint involvement is common, but usually not in the early stages. The glenohumeral and acromioclavicular joints are most likely to be involved, with typical signs being restriction of motion and pressure pain below and around the rostral process. 5. Neck: About 25% of patients with early rheumatoid arthritis have cervical spine involvement, and as the disease progresses eventually 60% to 70% of patients develop related symptoms, with lesions occurring mainly in the synovial bursa around the odontoid process and its associated ligaments. Neck pain and stiffness are common in rheumatoid arthritis, often invading the first and second cervical vertebrae. Progressive bone erosion can cause subluxation of the atlantoaxial joint, resulting in spinal compression and neurological symptoms, as well as torsion and compression of the vertebral artery, resulting in inadequate blood supply to the basilar artery, resulting in a range of clinical symptoms: abnormal limb movement, sphincter dysfunction, ataxia, nystagmus, and Swallowing difficulties, and can cause pain from the occiput to the scapula. 6. Knee: The knee is one of the most commonly involved and most disabling joints, with approximately l0% to 15% of rheumatoid arthritis patients having the knee as their first manifestation. Hypertrophy and effusion of the synovial membrane are common, and clinical symptoms include joint stiffness, pain, difficulty walking and sitting, and getting up. Atrophy of the quadriceps muscle may occur several weeks after the knee lesion and rapidly affect knee extension function. Late complications include flexion contracture, valgus deformity, and ligament instability of varying degrees. The fluid accumulation in the knee cavity may increase the pressure in the cavity during knee flexion, at which time the fluid is squeezed into the synovial bursa of the gastrocnemius-semimembranosus muscle on the posterior side of the joint, causing an enlargement of the bursa cavity and forming a fossa cyst called a Baker cyst, where an elastic soft tissue mass can be palpated, and the patient complains of pain and swelling behind the knee, occasionally the cyst grows rapidly or ruptures causing symptoms similar to acute thrombophlebitis, called “pseudo-thrombophlebitis”. 7, hip: hip lesions are uncommon and often occur in the late stage of the disease, patients often complain of groin discomfort, followed by hip, lower back or knee pain, swelling and pressure pain are rare, and can only be judged by gait and restricted joint movement to have hip lesions. In the late stage, there may be destruction of the femoral head.