Phase-Contrast Radiography Enables Detection of Early Changes in Articular Cartilage in a Mouse Model of Osteoarthritis.

The aim of this study was to investigate the potential of using phase-contrast radiography to detect early changes in articular cartilage in a mouse model of osteoarthritis. An iodoacetate-induced mouse model of osteoarthritis was used. Mice with iodoacetate-induced osteoarthritis were euthanized at 1 and 2 wks after injection. Specimens were obtained by sectioning mouse tissue into 5-mm-thick slices. Sections were examined using synchrotron x-rays from the 7B2 beamline at the Pohang Light Source. Magnified microradiographic images, obtained by phase-contrast radiography, were used to identify changes in articular cartilage and the subchondral bone. Refraction-enhanced phase-contrast radiography enabled detailed microscopic and macroscopic observation of articular cartilage by a noninvasive technique. Detailed microscopic images revealed partially damaged articular cartilage, containing an irregular trilaminar zone, at 1 wk after injection. At 2 wks after injection, a necrotic cleft was clearly visible, along with collapse of the trilaminar zones. Shrunken chondrocytes and chondrocyte clusters of variable sizes were also observed. Phase-contrast radiography is a feasible technique for the early detection of osteoarthritis and is capable of detecting microstructural changes in articular cartilage.