Middle-aged adults with knee osteoarthritis present worse sarcopenia parameters, symptoms and functional performance

Abstract

Purpose: Osteoarthritis (OA) is the most common joint dysfunction in individuals from 40 years of age, presenting, among its characteristics, inflammation and degeneration caused by the destruction of articular cartilage, being the knee one of the most affected joints. In addition to OA, sarcopenia is another chronic health dysfunction, characterized by degenerative loss of skeletal muscle mass, quality, and strength associated with aging and immobility. Although there is still no evidence of a direct effect of sarcopenia on OA development nor the opposite relation, both musculoskeletal disorders may lead to common functional consequences. However, it is still unknown whether middle-aged adults with knee OA have a higher risk of developing sarcopenia in association with symptoms and functional impairment. Thus, the aim of this study was to evaluate sarcopenia parameters in middle-aged adults with knee OA (OA group - OAG) compared to non-knee OA individuals (control group-CG), as well as their clinical and functional parameters. Methods: Participants aged between 40 and 65 years old and BMI <35Kg/m2were included in this study. Individuals with knee OA, diagnosed and classified as grades 2 and 3 by the Kellgren & Lawrence (K&L) criteria were included in the OAG and individuals with K&L 0 and 1 were included in the CG. The European Working Group on Sarcopenia in Older People (EWGSOP) criteria was used for the diagnosis and classification of sarcopenia parameters. Three evaluation criteria were measured: appendicular skeletal muscle mass (ASM), muscle strength, and physical performance. For the evaluation of muscle mass, the Dual-energy X-ray absorptiometry (DXA) (Discovery A - Hologic) was used. Cutoff points of 7.26 kg / m2 for men and 5.5 kg / m2 for women were established. The skeletal muscle mass values extracted from DXA were described from the formula: ASM/height2(kg/m2). To evaluate the muscle strength, the Jamar handgrip dynamometer was used. Cutoff points of 30 kg for men and 20 kg for women were established. Physical performance was measured using the 40-meter Fast-paced Walk Test to obtain gait speed measured in m/s. The established cutoff point was 1m/s. In addition, the performance-based tests 30-seconds chair test and Stair climb test were also performed to evaluate the participants’ functional capacity, according to OARSI recommendations. The Western Ontario and McMaster Universities (WOMAC) questionnaire was used to evaluate participants’ clinical symptoms. For comparison between groups, the unpaired t-test was applied to each of the dependent variables. For all analyzes, a significance level of 0.05 (p<0.05) was adopted. Results: 40 participants were evaluated in this study. No statistically significant differences were observed between the groups in the participants' characteristics (age, weight, height and BMI - p>0.05). OAG presented statistically significant worse values in sarcopenia parameters than CG group, presenting lower ASM (p=0.041), worse performance on 40-meter Fast-paced Walk Test (p=0.020) and lower right (p<0.01) and left (p<0.01) handgrip strength. In addition, as expected, OAG participants had statistically significant higher scores for pain, stiffness, physical function, and total scores for the WOMAC questionnaire (p <0.001 for all domains) and lower functional performance in the 30s Chair Stand Test. (p = 0.001) and Stair climb test (p <0.001). Conclusions: In addition to worse symptoms and functional performance, middle-aged adults with knee OA have worse sarcopenia parameters than non-knee OA individuals. This may indicate that sarcopenia may be present early in these patients, so treatment and prevention strategies should also focus on these parameters.