title: Magnetic resonance imaging abnormalities in symptomatic and contralateral knees: prevalence and associations with traumatic history in general practice.
abstract: BACKGROUND
  After trauma, internal knee lesions are found in approximately two thirds of patients. However, magnetic resonance imaging abnormalities have also been described in asymptomatic volunteers.
  
  
  OBJECTIVE
  Not all visualized lesions in symptomatic posttraumatic knees are the result of recent trauma; there are subgroups of lesions that may be preexistent.
  
  
  METHODS
  Cross-sectional study (prevalence); Level of evidence, 2.
  
  
  METHODS
  Patients visiting their general practitioners after knee trauma were invited for magnetic resonance imaging of both knees. Prevalence of knee abnormalities was compared between symptomatic and asymptomatic knees. Multivariable analysis was performed to investigate the association between lesions that were seen in symptomatic and asymptomatic knees (ie, effusion and meniscal tears) and recent trauma, history of old trauma, age, and osteoarthritis.
  
  
  RESULTS
  In 134 participants, ligament lesions were found almost exclusively in symptomatic knees. Meniscal lesions and effusion were almost equally found in symptomatic and asymptomatic knees. Effusion was related to recent trauma (odds ratio, 14.0; 95% confidence interval, 5.0-39.6) and osteoarthritis (odds ratio, 4.7; 95% confidence interval, 1.4-15.5) but not to history of old trauma and age. Meniscal tears were more common in older patients (odds ratio, 1.09; 95% confidence interval, 1.05-1.12) but were not related to osteoarthritis. History of old trauma was more strongly related to the group of radial, longitudinal, and complex meniscal tears (odds ratio, 8.6; 95% confidence interval, 3.3-22.5) than to horizontal tears (odds ratio, 2.3; 95% confidence interval, 0.9-5.6). Recent trauma was not related to horizontal meniscal tears but was strongly related to other types of meniscal tears (odds ratio, 3.2; 95% confidence interval, 1.4-6.9).
  
  
  CONCLUSIONS
  Ligament knee lesions are most probably the result of recent trauma. Radial, longitudinal, and complex meniscal tears are strongly related to trauma, whereas horizontal meniscal tears and effusion may be preexistent in many cases.
authors.affiliation: Department of General Practice, Erasmus MC, Rotterdam, Netherlands. s.boks@erasmusmc.nl
authors.forename: Simone S
authors.initials: SS
authors.lastname: Boks
authors.forename: Dammis
authors.initials: D
authors.lastname: Vroegindeweij
authors.forename: Bart W
authors.initials: BW
authors.lastname: Koes
authors.forename: Myriam M G M
authors.initials: MM
authors.lastname: Hunink
authors.forename: Sita M A
authors.initials: SM
authors.lastname: Bierma-Zeinstra
mesh_terms: D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D005194:Family Practice; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis* / Q000453:epidemiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000453:epidemiology; D015995:Prevalence; D012421:Rupture