Osteoarthritis or degenerative joint disease (DJD) is an asymmetric, usually bilateral mechanical degenerative process that involves joints significantly involved in weight bearing, such as the hip, knee, and spine, and those involved in frequent repetitive mechanical trauma, such as the distal interphalangeal joints of the fingers, trapezium–first metacarpal joint, trapezium- scaphoid joint, and metatarsophalangeal joint of the great toe. It is the most common arthritis, and it is estimated that 80% of the population with more than 50 years will show radiographic evidence of osteoarthritis. The most common radiographic findings include the following:
- Nonuniform loss of joint space caused by cartilage degeneration in high load areas (e.g., the superior aspect of the hip and medial knee).
- Sclerosis of the subchondral bone.
- Osteophyte formation at the margins of the articular surfaces.
- Cystlike rarefactions in the subchondral bone that may collapse to produce marked joint deformities.
- Adjacent soft-tissue swelling (e.g., that which occurs with Heberden’s nodes of the distal interphalangeal joints of the fingers) (Fig. 6-39) (53).