DDx

• Osteoarthritis (degenerative joint disease) or inflammatory osteoarthritis
• Connective tissue disease, eg, rheumatoid arthritis, systemic lupus erythematosus, scleroderma, Sjögren’s syndrome, adult Still’s disease
• Seronegative spondyloarthropathy, eg, reactive arthritis (Reiter’s syndrome), psoriatic arthritis, ankylosing spondylitis, inflammatory bowel disease
• Infection, eg, Staphylococcus aureus septic arthritis, gonococcal arthritis, endocarditis, hepatitis B or hepatitis C, parvovirus B19, Lyme disease, rubella or post-rubella vaccination
• Crystal-induced, eg, gout, pseudogout
• Trauma
• Other joint disease, eg, Charcot (neuropathic) joint, sarcoidosis, tumor, paraneoplastic syndrome (eg, hypertrophic pulmonary osteoarthropathy, leukemia), avascular necrosis, amyloidosis, coagulopathy, sickle cell disease, Henoch-Schönlein purpura, relapsing polychondritis, Behçet’s syndrome, Whipple’s disease, palindromic rheumatism, ochronosis (alkaptonuria)
• Other non-joint disease, eg, tendonitis, bursitis, polymyalgia rheumatica, reflex sympathetic dystrophy