Relationship between subchondral bone microstructure and articular cartilage in the osteoarthritic knee using 3T MRI

Background: The importance of subchondral bone in the pathogenesis of osteoarthritis (OA) has drawn interest.

Purpose: To investigate subregional trabecular bone microstructural features and to determine the relationship between cartilage and trabecular bone in the osteoarthritic human knee.

Study type: Prospective study.

Subjects: In all, 92 knees were enrolled and divided into three groups: without OA, mild OA, and severe OA.

Sequence: A sagittal 3D balanced fast field echo (3D B-FFE) sequence and FatSat 3D fast field echo (3D-FFE) sequence at 3T MRI.

Assessment: The trabecular bone in 12 sites of the knee joint was evaluated using digital topological analysis, and the cartilage thickness in four sites was calculated.

Statistical test: Trabecular bone and cartilage parameters between groups were compared using analysis of variance (ANOVA) with Bonferroni adjustment, and their correlations were analyzed using Pearson's correlation coefficient.

Results: Within both femoral condyles, the trabecular bone structure deteriorated in mild OA, showing a lower bone volume fraction (BVF) (0.15 to 0.12, P < 0.05), higher erosion index (EI) (2.25 to 2.28, P < 0.01), and a lower plate-to-rod ratio (SCR) (6.22 to 5.96, P < 0.05). Within medial and lateral tibia, deterioration in the trabecular bone was also observed, demonstrating a lower BVF (0.15 to 0.12 P < 0.05) and a higher EI (2.25 to 2.61, P < 0.05). Cartilage attrition mainly occurred in the medial joint. Extensive correlations were found between the medial cartilage thickness and subregional trabecular parameters. There was mainly a positive correlation with both femoral BVFs (r > 0.3, P < 0.05), and a negative correlation with the tibia SCR (r < -0.2, P < 0.05).

Data conclusion: In the early stage of OA, trabecular bone osteoporotic changes were observed in both femoral condyles and the tibia. Based on a strong correlation with the medial cartilage thickness, the trabecular structural topological analysis may be useful for elucidating OA onset and progression.

Level of evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.