1. Imaging modalities such as radiography, ultrasound, CT arthrography, and MRI are used to evaluate articular cartilage and subchondral bone. MRI is the preferred method as it can detect early cartilage degeneration without radiation exposure.
2. Cartilage damage is graded on MRI from Grade I (mild increased signal) to Grade IV (full thickness defects). Subchondral bone changes like edema, fractures, and osteophytes also provide information about the severity and cause of injury or disease.
3. Techniques like dGEMRIC and T1ρ mapping can detect early biochemical changes in cartilage like glycosaminoglycan loss prior to macroscopic defects, helping evaluate and monitor treatments.