Comparison of physical function recovery in patients with rheumatoid arthritis and those with osteoarthritis after total knee arthroplasty

Patients with rheumatoid arthritis (RA) who have undergone primary total knee arthroplasty (TKA) have a different recovery process of walking ability compared with patients with osteoarthritis (OA). However, how this relates to pain and other physical functions is unknown. This study aimed to evaluate and compare physical function after TKA in patients with RA and knee OA. This study enrolled 146 patients (24 with RA and 122 with OA) who underwent primary TKA. Data on the following were collected pre- and post-TKA (3 weeks and 1 year): 10 Meter Walk Test (10MWT), Timed Up and Go (TUG) test, knee pain, physical activity, isometric knee extensor and flexor strength, passive knee extension and flexion angle, and one-leg standing time. Two-way repeated measures analysis of variance (ANOVA) with Bonferroni post hoc comparisons was performed to examine the influence of the different diseases on post-operative changes in physical function over time. The RA group had a significantly more severe pre-operative pain score than the OA group ( p ​< ​0.05). A two-way repeated measures ANOVA showed a significant group ​× ​time interaction in the TUG test and 10MWT time. The RA group had a slower pre-operative time in these tests than the OA group ( p ​< ​0.01). However, the TUG test and 10MWT time at 3 weeks and 1 year post-TKA were not significantly different between the two groups. In patients with RA, walking ability significantly improved at 3 weeks following TKA, and showed recovery from 3 weeks up to 1 year similar to patients with OA. • Recovery of walking ability after total knee arthroplasty (TKA) is disease-specific. • Study of post-TKA pain in patients with rheumatoid arthritis (RA) and osteoarthritis (OA). • Walking ability in RA was improved to the same level as OA at 1 year post-TKA. • Post-TKA pain management for RA patients is useful for improving walking ability.