Fig. 5

a Zoomed spoiled gradient, magnetic resonance image with fat saturation, of the first carpometacarpal joint (CMC1) in a healthy volunteer, showing a thick cartilage layer with high signal intensity. b Image of the CMC1 joint in a patient. Arrow indicates a thin band of high signal intensity, which was scored as partial loss of cartilage thickness (there appears to be some cartilage remaining). The image quality was rated as adequate. c Magnification of a histological section from the same patient; each tick on the scale bar represents 50 μm. The whole articular surface area in this patient had the same appearance, with only bare bone apparent