Vol.20 No.5

Original Article

Effect of total knee arthroplasty on disease activity in patients with established rheumatoid arthritis: 3-year follow-up results of combined medical therapy and surgical intervention

Authors

Koichiro Yano¹ , Katsunori Ikari¹ , Eisuke Inoue¹ , Asami Tokita¹ , Yu Sakuma¹ , Ryo Hiroshima¹ , Takuji Iwamoto¹ , Kosei Kawakami¹ , Atsuo Taniguchi¹ , Hisashi Yamanaka¹ , Shigeki Momohara¹

Received:

29 January 2010

Accepted:

7 April 2010

Published online:

19 May 2010

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Abstract

Though excellent clinical results have been reported for total knee arthroplasty (TKA) in rheumatoid arthritis (RA) patients, the medium-term effect of TKA on RA disease activity remains unknown. This analysis aimed to assess changes in disease activity after TKA in patients with established RA. We analyzed the systemic effects of TKA on RA disease activity 3 years after intervention. Routine clinical and laboratory assessments were recorded at baseline, less than less than 0.5 years after TKA, and 3 years after TKA. Of the registered RA patients, 130 TKA patients were followed for 3 years after surgery. RA disease activity was measured using the Disease Activity Score 28 (DAS28). Patients were divided into three groups by preoperative baseline DAS28: low (DAS28 ≤ 3.2, n = 8), moderate (DAS28 > 3.2 but ≤5.1, n = 68), and high (DAS28 > 5.1, n = 54) disease activity. The postoperative DAS28 (<0.5 years [DAS1] and 3 years [DAS3] after surgery) scores of each patient were compared to their baseline (DAS0) scores using the paired t-test. The mean DAS28 decreased from 4.85 (DAS0) to 4.14 (DAS1; P = 1.07E-12), and this decrease was sustained at 3 years (DAS3 = 3.97; P = 4.73E-15). Subanalysis results revealed a systemic effect of TKA on disease activity in patients with moderate or high disease activity (DAS0 = 4.33; DAS1 = 3.72 [P = 5.94E-06]; DAS3 = 3.81 [P = 7.89E-06]; and DAS0 = 5.79; DAS1 = 4.86 [P = 1.14E-08]; DAS3 = 4.37 [P = 1.03E-11], respectively). While no significant changes in medication were noted, the average dose of prednisolone tended to decrease over time. We conclude that TKA, which is known to result in good clinical outcomes for damaged knees, has a secondary systemic effect on RA disease activity. Combination therapy consisting of medical treatment and surgical intervention is thought to effectively improve the condition of RA patients who have destructive arthritis in the knee joint, with the effect lasting for at least 3 years.

Key words

Disease activity score - Medical therapy - Rheumatoid arthritis - Surgical intervention - Total knee arthroplasty