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RESEARCH PRODUCT

Association between radiography-based subchondral bone structure and MRI-based cartilage composition in postmenopausal women with mild osteoarthritis

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Abstract Objective: Our aim was to investigate the relation between radiograph-based subchondral bone structure and cartilage composition assessed with delayed gadolinium enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T₂ relaxation time. Design: Ninety-three postmenopausal women (Kellgren–Lawrence grade 0: n = 13, 1: n = 26, 2: n = 54) were included. Radiograph-based bone structure was assessed using entropy of the Laplacian-based image (ELap) and local binary patterns (ELBP), homogeneity indices of the local angles (HIAngles,mean, HIAngles,Perp, HIAngles,Paral), and horizontal (FDHor) and vertical fractal dimensions (FDVer). Mean dGEMRIC index and T₂ relaxation time of tibial cartilage were calculated to estimate cartilage composition. Results: HIAngles,mean (rs = −0.22) and HIAngles,Paral (rs = −0.24) in medial subchondral bone were related (P < 0.05) to dGEMRIC index of the medial tibial cartilage. ELap (rs = −0.23), FDHor,0.34 mm (r = 0.21) and FDVer,0.68 mm (r = 0.24) in medial subchondral bone were related (P < 0.05) to T₂ relaxation time values of the medial tibial cartilage. FDHor at different scales in lateral subchondral bone were related (P < 0.01) to dGEMRIC index (r = 0.29–0.41) and T₂ values of lateral tibial cartilage (r = −0.28 to −0.36). FDVer at larger scales were related (P < 0.05) to dGEMRIC index (r = 0.24–0.25) and T₂ values of lateral tibial cartilage (r = −0.21). HIAngles,Paral (r = −0.25) and FDVer,0.68 mm (rs = 0.22) in the lateral tibial trabecular bone were related (P < 0.05) to dGEMRIC index of the lateral tibial cartilage. Conclusion: Our results support the presumption that several tissues are affected in the early osteoarthritis (OA). Furthermore, they indicate that the detailed analysis of radiographs may serve as a complementary imaging tool for OA studies.