Overview
The pattern of joint involvement in arthritis can be used clinically to identify the most likely pathology.
Arthritis may affect one joint or multiple joints in a symmetric or asymmetric pattern.
Monoarthritis
Monoarthritis is the inflammation of a single joint. This is commonly due to trauma, gout, or infection.
Monoarthritis may also be the first manifestation of a polyarthritis, such as rheumatoid arthritis, seronegative spondyloarthropathy or connective tissue disease.
Causes of Monoarthritis
- Trauma - fracture, soft tissue injury
- Crystal arthropathies - gout, pseudogout
- Septic arthritis - gonococcal, Staph, Strep, gram negative
- Osteoarthritis
- Haemarthrosis (traumatic or in the setting of coagulopathy)
- Malignancy - sarcoma, metastasis
- Avascular necrosis
- Tendonitis
- Bursitis
Polyarthritis
Polyarthritis refers to inflammation affecting multiple joints (usually five or more). This may be symmetrical or asymmetrical, and may have a particular pattern of joint involvement.
Patterns of Involvement
- Symmetric polyarthritis: affects joints both sides in a symmetrical mannerRheumatoid arthritis, systemic lupus erythematosus
- Asymmetric polyarthritis: patchy joint involvementAnkylosing spondylitis, psoriatic arthritis, reactive arthritis, grout, pseudogout, septic arthritis
- Distal interphalangeal (DIP) involvementSuggests osteoarthritis
- MCP and PIP involvement with DIP sparingClassically rheumatoid arthritis
- Sacroiliac involvementSuggests spondyloarthropathy - ankylosing spondylitis or psoriatic arthritis
- Hip & knee involvementSuggests osteoarthritis
- Ankle involvementSuggests spondyloarthropathy - ankylosing spondylitis, psoriatic arthritis, reactive arthritis
- Metatarsophalangeal involvementClassically gout (involvement of this joint with gout is called podagra)
Causes of Polyarthritis
- Rheumatoid arthritis
- Seronegative spondyloarthropathies - reactive arthritis, ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease-related arthritis
- Crystal arthropathies - gout, pseudogout
- Osteoarthritis
- Connective tissue disease - systemic lupus erythematosus, mixed connective tissue disease
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