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Correlation between the subchondral bone marrow lesions and cartilage repair tissue after matrix-associated autologous chondrocyte implantation in the knee: a cross-sectional study

Background The contribution of the subchondral bone in the development and progression of osteoarthritis (OA) has long been recognized, but its role in cartilage repair procedures has only recently attracted more attention. Purpose To explore the correlation between the cartilage repair tissue (RT) and the subchondral bone marrow lesions (BMLs) after matrix-associated autologous chondrocyte implantation (MACI) in the knee joint. Material and Methods A total of 30 patients who underwent MACI in the knee from January 2015 to June 2018 and follow-up magnetic resonance imaging (MRI) scan were recruited in this study. The MRI results of cartilage RT were evaluated using T2* relaxation time. Subchondral BMLs were also qualitatively evaluated by use of the two-dimensional proton density-weighted fat-suppressed (2D-PD-FS) and three-dimensional dual-echo steady-state (3D-DESS) sequences. Results The univariate analysis displayed a significant negative correlation between subchondral BMLs and cartilage RT (P < 0.01). In the minimally adjusted model (only age, sex, and body mass index [BMI] adjusted), the results did not show obvious changes (β = –6.54, 95% confidence interval [CI] = –10.99 to –2.09; P = 0.008). After adjustment for the full models (age, sex, BMI, defect size, combined injury, and preoperative duration of symptoms adjusted), the connection was also detected (β = –6.66, 95% CI –11.82 to –1.50; P = 0.019). Conclusion After MACI, the subchondral BMLs are significantly correlated with cartilage RT-T2* relaxation time. The role of subchondral bone in cartilage repair procedures should not be underestimated.