FRI0385 MUSCLE FUNCTION AND QUALITY BUT NOT MASS PROTECT AGAINST MORE SEVERE KNEE PAIN TRAJECTORIES

Abstract

Background:Evidence suggests that periarticular muscles have a role in the pathogenesis of pain, but results have not been consistent. We recently reported that pain population is heterogenous and consists of different subgroups of which the causes and mechanisms differ.Objectives:To examine the association of muscle mass, leg strength, knee extensor strength, low-limb muscle quality with knee pain trajectories.Methods:Data on 975 participants from a population-based older adult cohort study were utilised. Dual-energy X-ray absorptiometry was used to assess muscle/fat mass. Leg strength in both legs and dominant knee extensor strength were measured. Low-limb muscle quality was calculated (i.e. leg strength divided by lower-limb muscle mass). The Western Ontario and McMaster Universities Osteoarthritis Index pain questionnaire was used to measure knee pain at each time-point. Radiographic knee osteoarthritis (ROA) was assessed by X-ray. Group-based trajectory modelling was applied to identify pain trajectories. Multi-nominal logistic regression was used for the analyses.Results:A total of 975 participants [Mean±SD: age 62.2±7.4 years, body mass index (BMI) 27.8±4.6 kg/m2and 51% of females] were included in the analysis. Three distinct pain trajectories were identified: ‘Minimal pain’ (53%), ‘Mild pain’ (34%) and ‘Moderate pain’ (13%). In multivariable analysis, both greater total and low-limb muscle mass were associated with an increased risk of ‘Mild pain’ [total muscle mass: relative risk (RR): 1.51 per SD increase, 95%CI: 1.14−1.98; low-limb muscle mass RR: 1.33 per SD increase, 95%CI: 1.07−1.66] and ‘Moderate pain’ [total muscle mass: RR: 2.57 per SD increase, 95%CI: 1.70−3.89); low-limb muscle mass RR: 2.03 per SD increase, 95%CI: 1.47−3.80)] compared to the ‘Minimal pain’ trajectory group. After further adjustment for fat mass, these associations disappeared. Total muscle mass percentage was associated with a reduced risk of being worse pain trajectories. In relative to the ‘Minimal pain’ trajectory group, leg strength, knee extensor strength and quality were associated with a reduced risk of being in more severe pain trajectories after adjustment for covariates (RR=0.56 to 0.71 per SD increase, all P<0.05). Similar results were observed in those with ROA.Conclusion:Muscle percentage, strength and quality, but not muscle mass itself are associated with a reduced risk of being more severe pain trajectories, suggesting that improving muscle composition, muscle function and power are of more clinically relevance to preventing the development and maintenance of worse pain trajectories.Disclosure of Interests:None declared