Assessing cartilage directly is more accurate than measuring joint-space width. Intact articular cartilage can be seen in these magnetic resonance images of the wrist as bands of high-signal-intensity tissue lining the surfaces of the bones and showing sharp contrast with low-signal-intensity joint fluid along the articular surfaces, and very low-signal-intensity bone cortex and suppressed marrow fat along the subchondral surfaces. Follow-up image (B) shows narrowing of the radioscaphoid joint space (arrows) relative to that in image (A). However, this narrowing is the result of displacement of joint fluid from between the intact articular cartilage surfaces because of abduction of the wrist rather than because of thinning of the cartilage plates themselves. Thus, joint-space width can be an inaccurate measure of cartilage thickness.
Peterfy et al. Arthritis Research & Therapy 2013 15:R44 doi:10.1186/ar4202