Simultaneous computed tomography of articular cartilage and subchondral bone

SummaryObjectiveContrast agent enhanced computed tomography (CECT) may be used to detect depletion of superficial proteoglycans in articular cartilage. In principle, computed tomography can also be used to diagnose the state of subchondral bone. Because osteoarthritis affects both cartilage and bone, we aimed to evaluate the feasibility of the CECT to simultaneously assess the state of these tissues. Further, we studied the spatial variation of contrast agent content in the CECT, properties of subchondral bone and the mechanical stiffness of articular cartilage across the bovine medial tibial plateau.MethodsOsteochondral samples (n=10) were prepared from fresh and visually intact bovine medial tibial plateaus. The dynamic mechanical modulus of the samples was measured using an arthroscopic indentation device. Subsequently, the samples were scanned with a peripheral quantitative computed tomography (pQCT) device prior to and after 35.5h of immersion in an anionic iodinated contrast agent, (ioxaglate) solution. The thickness of the cartilage was measured with ultrasound and pQCT.ResultsIn the medial tibial plateau, the site-dependent variation in the dynamic modulus, thickness of the cartilage, thickness of the subchondral plate and contrast agent content in the superficial cartilage was statistically significant (P<0.01). The linear correlation between the superficial contrast agent content and the dynamic modulus was ρ=−0.80 (P