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Arthritis is a broad term referring to inflammation of joints, clinically manifesting as pain, swelling, stiffness, and restricted mobility. It is not a single disease but a group of disorders involving articular and periarticular structures.

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https://youtu.be/OhbzcJgpTjI

Classification

Type	Condition
Degenerative arthritis	‣
Inflammatory arthritis	‣
	‣:
• Ankylosing spondylitis (AS)
• Psoriatic arthritis (PsA)
• Reactive arthritis (ReA) “Reiter syndrome”
• IBD associated arthropathy
	Infectious (septic arthritis): Pyogenic, tuberculous, Lyme disease.
‣	• Gout
• Pseudogout (CPPD)
• Hydroxyapatite crystal deposition disease (HADD)
Hematologic arthropathy	‣
Metabolic arthropathy	Hemochromatosis, Wilson’s disease, ochronosis.

Etiopathogenesis

Autoimmune: Breakdown of immune tolerance → synovial inflammation (RA, psoriatic arthritis).
Degenerative: Age-related cartilage wear, subchondral bone remodeling, osteophyte formation (OA).
Crystal-induced: Deposition of urate (gout) or CPPD crystals triggers neutrophil-mediated inflammation.
Infective: Direct microbial invasion of synovium and cartilage destruction.
Metabolic: Abnormal deposition of metabolic products (iron, copper, homogentisic acid).

Clinical Features

Pain (mechanical in OA; inflammatory in RA).
Swelling and warmth (prominent in inflammatory/infectious arthritis).
Morning stiffness (>1 hr in RA, <30 min in OA).
Joint deformity in chronic disease (RA: ulnar deviation, swan-neck deformity).
Systemic features in autoimmune disease: fatigue, fever, extra-articular involvement (lungs, heart, eyes).