MR Imaging Study Of Changes In The Knee Joint Structural Damages During The Development Of Rheumatoid Arthritis

Objective:To investigate the structural damages of knee joint and longitudinal changes during the transition from preclinical stage to arthritis stage of rheumatoid arthritis(RA),and to further compare the structural damages and changes of knee joint during the development of RA and osteoarthritis(OA).Methods:Data from the Osteoarthritis Initiative(OAI).(1)Study subjects:RA group(n=34 knee joints):The included subjects were diagnosed with RA during the follow-up of 12 to 48 months,and all enrolled knees had a Kellgren and Lawrence(KL)grade of 0 or 1 before RA diagnosis;Healthy controls(n=34 knee joints):Knees with age,sex,body mass index(BMI)matched with RA group and KL grade of 0 or 1 within 48 months of follow-up.OA group(n=34 knee joints):Knees with age,sex,BMI matched with RA group and with KL grade of 2 or 3 during follow-up from 12 to 48 months.(2)Magnetic resonance imaging(MRI):Sagittal IW 2D TSE,coronal IW 2D TSE,and 3D DESS sequences.(3)Two doctors used the MR Imaging Osteoarthritis Knee Score(MOAKS)to evaluate the knee cartilage defect,bone marrow lesions(BMLs),and synovitis at baseline(BL),P-1(one year before P0),and P0(the onset of RA or OA).(4)Statistics:The generalized estimating equation(GEE)was used to compare the differences of the total score of joint structure damages between groups at different time points,the differences of the total score of joint structure damages between different time points in each group,and the similarities and differences of the changing trend of the total score of joint structure damages with time in each group.Result:(1)RA group vs.control group:The results showed no statistical difference in the total scores of the three structural damages(knee cartilage defect,BMLs,and synovitis)between the RA group and the control group at the time of BL;At P-1,there were significant differences in the total scores of BMLs and synovitis between two groups(P=0.022;P=0.033,respectively);At P0,the total scores of three structural damages in RA group were higher than those in the control group.There were significant differences in the total scores of the three structural damages in the RA group at different time points.From BL to P-1,the total score of the cartilage defect and BMLs were significantly higher in the RA group.From P-1 to P0,the total cartilage defect score increased from 8.59 to 10.88(P=0.002),and the synovitis total score increased from 1.29 to 1.76(P=0.003).(2)RA group vs.OA group:The results showed no statistical difference between the RA group and the OA group in the total scores of the three structural damages at each time point.There were statistically significant differences in the total scores of the three structural damages at different time points in the RA group(cartilage defect:P<0.001;BMLs:P=0.030;synovitis:P<0.001);There were significant differences in the total score of cartilage defects and BMLs in the OA group at each time points(P<0.001;P=0.009,respectively).From BL to P0,the total score of synovitis changed significantly in the RA group,and the total score of BMLs in the OA group changed significantly,but there was no significant difference in the differences between the RA and OA groups in the three structural damages.Conclusion:BMLs and synovitis were present in the knee joint one year before the onset of RA,and all three structural damages were present at the onset of RA.What’s more,cartilage defects and synovitis progressed more significantly during the transition from the preclinical stage to the clinical arthritis stage.It was difficult to differentiate between RA and OA early knee structural damages,but RA synovitis and mild-to-moderate OA BMLs progressed significantly during the transition from preclinical stage to clinical arthritic stage.