title: Prevalence and associated factors of Osgood-Schlatter syndrome in a population-based sample of Brazilian adolescents.
abstract: BACKGROUND
  Osgood-Schlatter (OS) syndrome is a disease of the musculoskeletal system often observed during the bone growth phase in adolescents. HYPOTHESIS/ PURPOSE: Demographic and anthropometric factors and those linked to the practice of sports may be related to the prevalence of OS. The aim of the present study was to describe the epidemiologic profile and associated factors of individuals with OS syndrome in a population-based sample of Brazilian adolescents.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  A cross-sectional study was conducted with 956 adolescent students (474 boys, 482 girls) from 2008 to 2009 enrolled in the school system of Natal, Brazil. The age ranged between 12 and 15 years (13.7 ± 1.04 years). Tests were performed to assess the anthropometric and clinical aspects related to OS. To confirm the diagnosis of OS syndrome, the participant had to fulfill all the following clinical criteria: pain with direct pressure on the tibial apophysis; aforementioned pain before, during, and after physical activities; enlargement or prominence of the tibial apophysis; pain with resisted knee extension; and pain from jumping.
  
  
  RESULTS
  The prevalence of OS in the sample was 9.8% (11.0% of boys and 8.3% of girls; boys, 13.5 ± 1.07 years; girls, 13.6 ± 1.01 years). The results showed that 74.6% of the students suffered from muscle shortening. Multivariate analysis using logistic regression showed that the factors associated with the presence of OS were the regular practice of sport activity (odds ratio, 1.94; 95% confidence interval, 1.22-3.10) and the shortening of the rectus femoris muscle (odds ratio, 7.15; 95% confidence interval, 2.86-17.86).
  
  
  CONCLUSIONS
  The regular practice of sports in the pubertal phase and the shortening of the rectus femoris muscle were the main factors associated to the presence of OS syndrome in the students.
authors.affiliation: Department of Physiotherapy, Federal University of Rio Grande do Norte, Campus Universitário Lagoa Nova, CEP, Natal-RN 59072-970 Brazil. roguerra@ufrnet.br
authors.forename: Gildásio Lucas
authors.initials: GL
authors.lastname: de Lucena
authors.forename: Cristiano
authors.initials: C
authors.lastname: dos Santos Gomes
authors.forename: Ricardo Oliveira
authors.initials: RO
authors.lastname: Guerra
mesh_terms: D000293:Adolescent; D000886:Anthropometry; D001938:Brazil / Q000453:epidemiology; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D016017:Odds Ratio; D055034:Osteochondrosis / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D015995:Prevalence; D012044:Regression Analysis