Knee pain in adolescents: prevalence, risk factors, and functional impairment

To investigate knee pain prevalence, associated factors, and functional impairment among adolescents.

This was a cross-sectional study conducted between May and June 2014 with a random sample of 619 adolescents aged between 10 and 17 years. Knee pain prevalence was investigated using the Nordic Questionnaire for Osteomuscular Symptoms and a number of independent variables (demographic data, nutritional status, form of carrying backpacks, and pain during and after walking) obtained by self-report questionnaires. Physical impairment of the knee was assessed using the Brazilian version of the Knee injury and Osteoarthritis Outcome Score questionnaire. Poisson regression analysis was used to estimate the ratios of crude and adjusted knee pain association with the investigated factors. ANOVA and Kruskal-Wallis tests were used to compare median functional impairment.

Knee pain prevalence over the last 7 days was 22.6%. Factors having significant association with the outcome were: being between 12 and 14 years old (PR: 1.67; 95% CI: 1.07-2.58; p<0.01), being between 15 and 17 years old (PR: 2.44; 95% CI: 1.51-3.94; p=0.01), and not doing physical education at school (PR: 0.54; 95% CI: 0.35-0.82; p=0.01). Total functional capacity among adolescents with pain was significantly lower among girls (68.7 points; PD±15.1) when compared with boys (74.3 points; PD±12.7) (p=0.02). The mean value of disabling pain was lower (55.1 points; PD±12.3) among adolescents who were physically active in their leisure time compared to those who were insufficiently active (60.4 points; PD±12.4) (p=0.02).

The results of this study show that knee pain among adolescents with no previous history should be investigated, particularly among older adolescents who do not have physical education at school, since it is highly prevalent and can result in functional impairment. Regarding functionality, more attention should be given to girls and adolescents who were physically active in their leisure time.