- degeneration of cartilage (with structural and functional failure of synovial joints)

- most common type of joint disease

- oligoarticular

- females: hands and knees- males: hips

Morphology- bone eburnation- narrowed joint space- subchondral sclerosis- cysts- osteophytes

Clinical course- pain that worsens with use- morning stiffness- crepitus- Heberden nodes (bone swellings in the DIP)