title: Only MR can safely exclude patients from arthroscopy.
abstract: OBJECTIVE
  The aim of this study was to determine in patients with subacute knee complaints and normal standardized physical examination the fraction of magnetic resonance imaging (MRI) studies showing arthroscopically treatable intra-articular pathology.
  
  
  METHODS
  There were 290 consecutive patients (between 16 and 45 years) with at least 4 weeks of knee complaints and low clinical suspicion of intra-articular pathology based on physical exam. Two hundred seventy-four patients were included. Sixteen patients with prior knee surgery, rheumatic arthritis, or severe osteoarthritis were excluded. MRI was used to assign patients to group 1 (treatable abnormalities) or group 2 (normal or no treatable findings), depending on whether MR demonstrated treatable pathology. Arthroscopy was performed in group 1 patients. If symptoms persisted for 3 months in group 2 patients, cross over to arthroscopy was allowed.
  
  
  RESULTS
  MR showed treatable pathology in 73 patients (26.6%). Arthroscopy was performed in 64 patients of 73 patients (group 1). In 52 patients (81.3%, 95% confidence interval (CI) 71.4-91.1%), arthroscopy was therapeutic. Of the 13 arthroscopies (6.5%) in group 2, four were therapeutic (30.8%, 95% CI 1.7-59.8). The highest fraction of MR studies showing treatable pathology was found in males, aged over 30 years, with a history of effusion (54.5%, six of 11 patients).
  
  
  CONCLUSIONS
  Authors believe that the negative predictive value of clinical assessment in patients with subacute knee complaints is too low to exclude these patients from MR. MR should at least be considered in male patients aged 30 years and over with a history of effusion.
authors.affiliation: Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands. p.w.j.vincken@lumc.nl
authors.forename: Patrice W J
authors.initials: PW
authors.lastname: Vincken
authors.forename: Bert P M
authors.initials: BP
authors.lastname: ter Braak
authors.forename: Arian R
authors.initials: AR
authors.lastname: van Erkel
authors.forename: Rolf M
authors.initials: RM
authors.lastname: Bloem
authors.forename: Peter A
authors.initials: PA
authors.lastname: van Luijt
authors.forename: L Napoleon J E M
authors.initials: LN
authors.lastname: Coene
authors.forename: Sam
authors.initials: S
authors.lastname: De Lange
authors.forename: Johan L
authors.initials: JL
authors.lastname: Bloem
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis* / Q000601:surgery*; D007718:Knee Injuries / Q000175:diagnosis* / Q000601:surgery*; D007719:Knee Joint / Q000473:pathology / Q000601:surgery; D008297:Male; D018579:Patient Selection; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult