Background/Purpose:

In patients with knee osteoarthritis activity limitations and disease progression have been associated with muscle weakness (OA). Muscle weakness might be determined by factors such as increased pain, immobilization, disuse, avoidance of activities and aging. Additionally, recent cross-sectional studies have found an association between elevated inflammatory markers and a decrease in knee muscle strength in this group of patients (1;2). However, longitudinal studies which assess the association between inflammatory markers and muscle strength in patients with OA are still needed. Therefore, the aim of the study was to examine the associations of serum c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) with changes in muscle strength in patients with knee osteoarthritis (OA) after two years.

Methods:

Data from 186 patients with knee OA part of the Amsterdam Osteoarthritis cohort (AMS-OA) were gathered at baseline and at two years follow up. CRP (mg/l) and ESR (mm/l) were measured in serum from patients’ blood. Strength of quadriceps and hamstrings muscles was assessed using an isokinetic dynamometer. Univariable and multivariable linear regression analyses were used to assess the association of CRP and ESR with changes in muscle strength, adjusting for relevant confounders.

Results:

Persistently elevated or increased serum CRP values (β=-0.23; p=0.002), but not ESR values (β=-0.05; p=0.55), were associated with a decrease in knee muscle strength after two years, even after adjustment for age, sex, comorbidities, NSAIDs use, BMI, pain, physical activity and baseline muscle strength.

Conclusion:

Our results indicate that persistently elevated or an increase in inflammatory markers are independently related to decreased muscle strength in patients with knee OA. Although the mechanism to explain this relationship is not clear yet, targeting inflammation might have the potential to control the loss of muscle strength in this group of patients.

References 

   (1)    Levinger I, Levinger P, Trenerry MK, Feller JA, Bartlett JR, Bergman N et al. Increased inflammatory cytokine expression in the vastus lateralis of patients with knee osteoarthritis. Arthritis Rheum 2011; 63(5):1343-1348.

   (2)    Sanchez-Ramirez DC, van der LM, van der EM, Gerritsen M, Roorda LD, Verschueren S et al. Association of serum C-reactive protein and erythrocyte sedimentation rate with muscle strength in patients with knee osteoarthritis. Rheumatology (Oxford) 2013; 52(4):727-732.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/c-reactive-protein-but-not-erythrocyte-sedimentation-rate-is-associated-with-decrease-in-muscle-strength-in-patients-with-knee-osteoarthritis-a-2-year-follow-up-study/