Exercise can reverse quadriceps sensorimotor dysfunction that is associated with rheumatoid arthritis without exacerbating disease activity

Abstract

Objectives: To compare quadriceps sensorimotor function, lower limb functional performance and disability in patients with rheumatoid arthritis (RA) and healthy subjects, and to investigate the efficacy and safety of a brief rehabilitation regime.

Methods: Quadriceps strength, voluntary activation, proprioceptive acuity and the aggregate time [aggregate functional performance time (AFPT)] taken to perform four common activities [aggregate functional performance time (AFPT)] were compared between 103 RA patients who had lower limb involvement and 25 healthy subjects. In addition, disability (Health Assessment Questionnaire), clinical disease activity and the plasma concentration of proinflammatory cytokines were measured in the RA patients. In a follow-on randomized controlled trial of rehabilitation, these variables were used as baseline data for 93 of the RA patients, who were randomized to a rehabilitation or a control group. Changes in the variables were analysed within and between groups.

Results: Compared with healthy subjects, RA patients had weaker quadriceps [mean difference 157 N; 95% confidence interval (CI) 125-189], poorer activation (8%, 95% CI 4.5-15) and proprioceptive acuity (0.8 degrees, 95% CI 0.4-1.3) and took longer to perform the AFPT (34 s, CI 23.5-44.8). Rehabilitation increased quadriceps strength (mean increase 61 N, 95% CI 28-95) and voluntary activation (8%, 95% CI 3-12.4) and decreased the AFPT (12.3 s, 95% CI -2 to 27.7) and subjective disability (0.21 HAQ points, 95% CI 0-0.35) without exacerbating disease activity. All the improvements were maintained at the 6-month follow-up. There was no change during the control period.

Conclusions: Patients with RA that affected their lower limb had quadriceps sensorimotor deficits that were associated with lower limb disability. A clinically applicable rehabilitation regime increased quadriceps sensorimotor function and decreased lower limb disability without exacerbating pain or disease activity. For patients with well-controlled RA that causes lower limb involvement, the regime is effective and safe.