Pain in multiple joints

Polyarticular arthralgias can be caused by arthritis or extra-articular disorders (eg, polymyalgia rheumatica and fibromyalgia).

Arthritis can be inflammatory and non-inflammatory (for example, osteoarthrosis). Inflammatory arthritis can involve either only peripheral joints or peripheral joints together with axial ones. Inflammatory arthritis accompanied by damage to no more than 4 joints is called peripheral oligoarthritis. Involvement of more than 4 joints is called peripheral polyarthritis. Each of them has its own distinctive characteristics.

Often arthritis is transient and resolves on its own or its manifestations may not meet the criteria of any specific pathology; in such cases, treatment can be started based on a preliminary diagnosis. For all atypical and unclear

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The most common causes of polyarthritis

Peripheral polyarthritis

• Rheumatoid arthritis
• Systemic lupus erythematosus
• Viral arthritis
• Serum sickness
• Psoriatic arthritis

Peripheral oligoarthritis

• Behcet's disease
• Enteropathic arthritis
• Infective endocarditis
• Gout (or pseudogout)
• Psoriatic arthritis
• Reactive arthritis
• Rheumatic fever
• Arthritis in Lyme disease

Peripheral arthritis with damage to axial joints

• Ankylosing spondylitis
• Enteropathic arthritis
• Psoriatic arthritis
• Reactive arthritis

Diagnosis of pain in multiple joints

Clinical data, particularly the medical history, are most important for diagnosis.

History. Localization of pain allows us to determine the type of affected anatomical structure (joint, bone, tendon, joint capsule, muscles, other soft tissue structures, nerves). The inflammatory nature of arthritis may be indicated by the presence of morning stiffness, non-traumatic swelling of the joint, increased body temperature, and decreased body weight. Diffuse, vague, or intermittent pain may be associated with fibromyalgia or functional disorders.

Back pain along with the development of arthritis suggests the presence of spondyloarthropathy, such as ankylosing spondylitis. Arthritis associated with urethritis and gastrointestinal disorders is most often reactive. In particular, diarrhea and abdominal pain are characteristic of arthritis associated with inflammatory bowel disease.

Physical examination. Increased body temperature, weakness, skin rashes may be observed in systemic rheumatic and non-rheumatic diseases. Examination of the musculoskeletal system allows us to establish whether the disorder is intra-articular in nature, and if so, whether it is accompanied by inflammation. Long-term arthritis may lead to a limitation of the range of passive movements in the joint.

Evaluation of the presence of periarticular changes may also be useful in the differential diagnosis of certain diseases. For example, concomitant tendinitis is characteristic of gonococcal arthritis, RA and other systemic diseases; bone pain is characteristic of sickle cell anemia and hypertrophic pulmonary osteoarthropathy; tophi are characteristic of gout; rheumatic nodules are characteristic of RA.

Examination of the hands is also useful for the differential diagnosis of arthritis. Swan-neck or buttonhole deformities are characteristic of long-standing RA. Distal interphalangeal joint involvement with nail erosion and asymmetrical involvement suggests psoriatic arthritis. Asymmetrical involvement of the finger joints may also occur in reactive arthritis; asymmetrical involvement of the distal interphalangeal joints and the presence of tophi in gout. Skin thickening and flexion contractures indicate systemic sclerosis. Raynaud's phenomenon may occur in progressive systemic sclerosis, SLE, or mixed connective tissue diseases. Club-shaped thickening of the fingertips and tenderness of the distal radius and ulna due to periostitis are seen in hypertrophic pulmonary osteoarthropathy. Pain with minor objective changes is typical for SLE, but in rarer cases it can also occur with dermatomyositis. At the same time, with these diseases, synovitis can develop, resembling that with RA. Erythema, accompanied by peeling of the skin of the extensor surface of the joints, especially the knees, can indicate dermatomyositis.

Examination. If clinical specific diagnosis is impossible, the inflammatory nature of arthritis can be confirmed by assessing the ESR and C-reactive protein concentration. Increased values of these indicators indicate inflammation, but are very non-specific, especially in adults. In addition, if the diagnosis is unclear, other studies may be performed.

Differential diagnostics of rheumatoid arthritis and osteoarthritis of the hand joints

Criteria	Rheumatoid arthritis	Osteoarthritis
Nature of edema	Synovial, capsular, soft tissue; firm to palpation - only in later stages	Bone density with irregular growths; in rare cases, soft cysts may form
Weakness	Always	Absent or mild, transient
Distal interphalangeal joint injury	Unusual, except for the thumb	Typical
Proximal interphalangeal joint disease	Typical	Often
Wrist-metacarpal joint injury	Typical	Uncharacteristic
Wrist joint damage	Usually or often	Rare, except for the carpometacarpal joint of the thumb

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