Background Patients with rheumatoid arthritis (RA) often require adequate disease control prior to total knee arthroplasty (TKA). At the same time, they may have worse outcomes and late complications compared to osteoarthritis (OA) patients.

Objectives To study the functional abilities of RA patients undergoing TKA compared to OA patients using the KSS scoring system.

Methods The study included 150 patients: 69 patients (46%) with RA and 81 patients (54%) with OA. 32% of them were males and 68% were females. Th average age of patients with RA was 59.0 [52; 64] years, while in OA group – 66.0 [61; 73] years. Among patients with RA, 60.9% had moderately active diseases and 23.2% had highly active disease prior to intervention. All patients underwent cemented TKA. All of them also completed KSS score prior to surgery, immediately after that and 3 and 12 months after the discharge. Statistical analysis was performed using SPSS version 23.0 (IBM Corp., Armonk, NY, USA). A p value of less than 0.05 was considered statistically significant.

Results Prior to intervention patients with RA had significantly lower KSS scores compared to OA patients (45.0 [40; 55] versus 60.0 [50; 60], p=0.00, Mann-Whitney). After the surgery KSS became comparable between the two groups (83.0 [74; 84] versus 82.0 [80.5; 85], p=0.754, Mann-Whitney). 3 months after the intervention RA patients had significantly higher KSS scores than prior to surgery (Mdn=88.0, n=69 versus Mdn=40.0, n=69, z=-7.23, p=0.00) or at discharge (Mdn=88.0, n=69 versus Mdn=83.0, n=69, z=-7.25, p=0.00, Wilcoxon test). The same trend was observed for KSS completed 12 months after the surgery (Mdn=93.0, n=69 versus Mdn=88.0 in KSS 3 months after the surgery, n=69, z=-7.26, p=0.00). At the same time, the results of KSS were comparable between RA and OA groups 3 and 12 months after the intervention (88.0 [88; 88] in RA group versus 88.0 [87; 89] in OA group, p=0.772, Mann-Whitney; 94.0 [93; 95] in RA group versus 94.0 [93;95] in OA group, p=0.702, Mann-Whitney, respectively).

Conclusion The functional abilities of patient with RA after TKA did not differ from those among OA patients regardless of diseases activity despite, despite the fact that among RA patients KSS scores were significantly lower prior to surgery. KSS scores of RA patients improved 3 and 12 months after the intervention and were comparable to OA group.

Reference [1] Kumagai K, Harigane K, Kusayama Y, Tezuka T, Inaba Y, Saito T. Total knee arthroplasty improves both knee function and disease activity in patients with rheumatoid arthritis. Mod Rheumatol. 2017 Sep;27(5):806-810. doi: 10.1080/14397595.2016.1265705. Epub 2016 Dec 16. PMID: 27919194.

Acknowledgements: NIL.

Disclosure of Interests None Declared.