Joint disease characterized by a degeneration of the joint complex (articular cartilage, subchondral bone, and synovium) that occurs with old age or from overuse.

Synovium:- Consists of connective tissue, blood vessels, lymphatic vessels- Type A cells: clear cellular debris- Type B cells: produce synovial fluid

Risk factors: Age, joint injury, mechanical stress, obesity, genetic factors

Aritcular cartilage starts to flake off into synovial space (= Joint mice). When type A cells try to remove cellular debris, immune cells are recruited → inflammation of synovium (= Synovitis) → Joint space narrowing→ Sclerotic bone→ Subchondral bone cysts→ Osteophytes

Symptoms: morning stiffness (<1 hour), worse at end of day, sharp ache/burning, worsens with activitiy, no swelling.- Heberden's nodes: DIP- Bouchard's nodes: PIP- Rhizarthosis: first carpometacarpal joint (between the trapezoid and the metacarpal bone)

Treatment:- Nonpharmacological: Losing weight, exercise, physical therapy- NSAIDs, hyaluronic acid injections, joint replacement