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Clinical Article
Mediating effect of synovitis in the association between BMI and the risk of total knee replacement
DING Yukun  ZHANG Xintao  ZHANG Xiaodong 

Cite this article as: DING Y K, ZHANG X T, ZHANG X D. Mediating effect of synovitis in the association between BMI and the risk of total knee replacement[J]. Chin J Magn Reson Imaging, 2023, 14(3): 122-127, 139. DOI:10.12015/issn.1674-8034.2023.03.021.

[Abstract] Objective To investigate the mediating effect of synovitis in the association between body mass index (BMI) and the risk of total knee replacement (TKR).Materials and Methods Case knees from the Osteoarthritis Initiative (OAI) participants with TKR at 12-60 months follow up were 1∶1 matched with control knees (no TKR throughout 60 months) by baseline age (±5 years), sex and Kellgren-Lawrence grade. Total 450 and 376 knees were included for the studies at baseline and at T0 (the previous follow-up before receiving TKR was termed as T0). According to the MRI Osteoarthritis Knee Score (MOAKS), effusion-synovitis and Hoffa-synovitis were scored semi-quantitatively. Conditional logistic regression estimated the correlation between BMI and TKR. Mediation analysis was used to evaluate the mediating effects of synovitis.Results The mean age of participants included for the study at baseline was (65.0±9.0) years, 59.2% were female, and 84.9% were White. The prevalence of effusion synovitis and Hoffa-synovitis at baseline and at T0 was higher in the case group than in the control group. Only at T0, there was a statistically significant associations between BMI with prevalence (χ2=9.173, P=0.010) and score (χ2=22.371, P=0.001) of effusion synovitis. After controlling for prior knee injury, BMI was associated with the risk of TKR (OR=1.121, 95% CI: 1.070-1.175, P<0.001); effusion synovitis at T0 had a significant mediating effect on BMI and TKR, indirect effect coefficient was 0.0298 (95% CI: 0.0132-0.0506), and the mediating contribution rate was 22.61%.Conclusions Our study is the first to indicate that effusion synovitis at T0 mediated the association between BMI and the risk of TKR. Attaching importance to MRI accurate evaluation and timely intervention of effusion synovitis in overweight or obese people is helpful to guide clinical practice to reduce the risk of TKR within the next year.
[Keywords] synovitis;osteoarthritis;body mass index;total knee replacement;mediating effect;magnetic resonance imaging

DING Yukun   ZHANG Xintao   ZHANG Xiaodong*  

Department of Medical Imaging, the Third Affiliated Hospital of Southern Medical University (Academy of Orthopedics Guangdong Province), Guangzhou 510630, China

Corresponding author: Zhang XD, E-mail:

Conflicts of interest   None.

ACKNOWLEDGMENTS General Project of President's Foundation of the Third Affiliated Hospital of Southern Medical University (No. YM2021012).
Received  2022-12-30
Accepted  2023-03-03
DOI: 10.12015/issn.1674-8034.2023.03.021
Cite this article as: DING Y K, ZHANG X T, ZHANG X D. Mediating effect of synovitis in the association between BMI and the risk of total knee replacement[J]. Chin J Magn Reson Imaging, 2023, 14(3): 122-127, 139. DOI:10.12015/issn.1674-8034.2023.03.021.

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