Background/Purpose: Treatment of rheumatoid arthritis (RA) has been dramatically changed by methotrexate (MTX) and biologics. According to introduction of these effective drugs for the control of disease activity, several changes in RA have been reported, especially in large joints. For the surgical numbers of total hip arthroplasty (THA) and total knee arthroplasty (TKA) in RA, most of studies showed decreased numbers of THA and TKA. The aim of this study was to investigate recent changes of number of surgery in the cases of THA and TKA, radiological findings, laboratory data, and patients’ background such as dose changes of drugs in the regional center for RA.

Methods: Between 2000 and 2015, 81 primary cases of THA and 239 primary cases of TKA were performed for RA. We analyzed the changes of the number of surgery. The age at the time of surgery, pre- and peri-operative laboratory data, such as white blood cell count (WBC), hemoglobin (Hb), and C-reactive protein (CRP) were reviewed. Also, medication with methotrexate (MTX) and corticosteroids (CS) were also carefully reviewed. In radiographic analyses of the hip, presence of acetabular protrusion and bone spur formation were evaluated. For femoral side, canal width ratio and cortical index were analyzed. For the cases of TKA, Larsen grades, preoperative femoral-tibial angle (FTA), and the appearance of bone spur were analyzed. Statistical analysis was performed using Cochran-Armitage test and linear regression analysis. The p-values less than 0.05 were considered statistically significant.

Results: The numbers of THA and TKA were significantly decreased with time (p<0.01, respectively). The average age at surgery showed continual increase (THA; p<0.05, TKA; p<0.01). The administration rate and averaged dose of CS were decreased with year (THA; p<0.05, TKA; p<0.01). On the other hand, although the average dose of MTX was increased with year (THA p<0.05, TKA p<0.01), the administration rate of MTX did not show any changes. The pre- and peri-surgical WBC and Hb did not show any changes with year. The averaged pre-surgical CRP decreased for THA （p<0.05）, but no significant difference was observed in TKA cases. Peri-surgical change of CRP did not show any changes for both group. In radiographic analyses, TKA cases did not show proportional changes in the Larsen grades. Although cases with a severe varus deformity were decreased, the mean FTA showed no changes during the period. Interestingly, we found the continual increase of the case number of RA knee with the spur formation (p<0.01). For THA cases, the presence of acetabular protrusion was decreased and the presence of bone spur formation around the acetabulum was increased. Although the canal width ratio did not show any changes, the cortical index were significantly increased with year (p<0.01).

Conclusion: In our registry, the numbers of primary THA and TKA for RA were significantly decreased during the time period. Our results may reflect increased cases of OA changes of hips and knees in RA. Tight control of the disease by effective drugs may influenced improved disease activity and prevention of joint destruction. 

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/recent-changes-of-radiological-findings-and-patients-background-of-rheumatoid-hip-and-knee/