Analysis of Quadriceps Strength and Knee Pain.

ABSTRACT

OBJECTIVE: To investigate the association of quadriceps strength with the presence of knee pain. DESIGN: This cross-sectional study was based on data from the 1999-2000 to 2001-2002 National Health and Nutrition Examination Survey. SETTING: This was a community-based study. PARTICIPANTS: This study included 2619 adults with complete data for knee pain, quadriceps strength, and covariates. INTERVENTION Not applicable. MAIN OUTCOME MEASURES: Self-reported knee pain. RESULTS: This study included 2619 individuals, 1287 (52.66%) of whom were women and 1543 (81.66%) identified as Non-Hispanic White. The mean ±standard deviation age was 62.48±9.71 years. After adjusting for covariates, the odds of knee pain decreased with every 20 N/m increase in quadriceps strength (odds ratio, 0.87; 95% confidence interval, 0.81-0.94). Individuals in the upper quartile of quadriceps strength had lower odds of knee pain than those in the lower quartile (Q4 vs Q1 [reference] odds ratio, 0.28, 95% confidence interval, 0.15-0.52; Ptrend=.006). Nonlinear analyses indicated L-shaped associations for knee pain. The subgroup analyses showed no significant interactions, except for sex (Pinteraction=.046). The significance of the sex interaction indicated a correlation exclusively in women. CONCLUSIONS: The results demonstrated an inverse association between quadriceps strength and the presence of knee pain. The subgroup analysis by sex showed that this inverse relationship was statistically significant in the women but not in the men subgroup.