title: MRI of the knee joint in asymptomatic adolescent soccer players: a controlled study.
abstract: OBJECTIVE
  The knee is the joint that is most frequently injured in boys 12-15 years old who practice soccer, and MRI is an accurate method of diagnosing sports-related injuries. The objective of this cross-sectional case-control study was to evaluate the knees of asymptomatic adolescent soccer players using open MRI.
  
  
  METHODS
  We evaluated 56 knees of 28 asymptomatic male adolescents 14-15 years old. Participants were divided into two groups and paired by age and weight: soccer players (28 knees) and control subjects (28 knees). All the examinations were performed using a 0.35-T open-field MRI unit and were evaluated by two experienced radiologists blinded to study groups. Bone marrow signal, articular cartilage, meniscus, and fat pad abnormalities and the amount of fluid were assessed.
  
  
  RESULTS
  In the group of soccer players, 18 knees (64.3%) had one or more MRI abnormalities, whereas in the control group nine knees (32.1%) had at least one MRI abnormality (p = 0.03). The prevalence of bone marrow edema was much greater in the group of soccer players (14 knees, 50%), whereas the same abnormality was found in only one knee (3.6%) in the control group (p = 0.0001). Other abnormalities that were not statistically significant with regard to study group were also found in the two groups: infrapatellar fat pad edema, popliteal cysts, and ganglion cysts.
  
  
  CONCLUSIONS
  Bone marrow edema is a prevalent abnormal finding on MRI scans of knees of asymptomatic adolescent soccer players. MRI findings should be interpreted cautiously and in close correlation with clinical findings.
authors.affiliation: Graduate School of Medicine, Pontifícia Universidade Católica do Rio, Grande do Sul, Avenida Ipiranga, 6690, Porto Alegre, RS, Brazil, CEP 90610-000. ricsoder@gmail.com
authors.forename: Ricardo Bernardi
authors.initials: RB
authors.lastname: Soder
authors.forename: Julyana Dias
authors.initials: JD
authors.lastname: Simões
authors.forename: Janine Bernardi
authors.initials: JB
authors.lastname: Soder
authors.forename: Matteo
authors.initials: M
authors.lastname: Baldisserotto
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007718:Knee Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012916:Soccer / Q000293:injuries*; D011795:Surveys and Questionnaires