title: The diagnostic value of the Clarke sign in assessing chondromalacia patella.
abstract: BACKGROUND
  Various techniques have been described for assessing conditions that cause pain at the patellofemoral (PF) joint. The Clarke sign is one such test, but the diagnostic value of this test in assessing chondromalacia patella is unknown.
  
  
  OBJECTIVE
  To (1) investigate the diagnostic value of the Clarke sign in assessing the presence of chondromalacia patella using arthroscopic examination of the PF joint as the "gold standard," and (2) provide a historical perspective of the Clarke sign as a clinical diagnostic test.
  
  
  METHODS
  Validation study.
  
  
  METHODS
  All patients of one of the investigators who had knee pain or injuries unrelated to the patellofemoral joint and were scheduled for arthroscopic surgery were recruited for this study.
  
  
  METHODS
  A total of 106 otherwise healthy individuals with no history of patellofemoral pain or dysfunction volunteered.
  
  
  METHODS
  The Clarke sign was performed on the surgical knee by a single investigator in the clinic before surgery. A positive test was indicated by the presence of pain sufficient to prevent the patient from maintaining a quadriceps muscle contraction against manual resistance for longer than 2 seconds. The preoperative result was compared with visual evidence of chondromalacia patella during arthroscopy.
  
  
  RESULTS
  Sensitivity was 0.39, specificity was 0.67, likelihood ratio for a positive test was 1.18, likelihood ratio for a negative test was 0.91, positive predictive value was 0.25, and negative predictive value was 0.80.
  
  
  CONCLUSIONS
  Diagnostic validity values for the use of the Clarke sign in assessing chondromalacia patella were unsatisfactory, supporting suggestions that it has poor diagnostic value as a clinical examination technique. Additionally, an extensive search of the available literature for the Clarke sign reveals multiple problems with the test, causing significant confusion for clinicians. Therefore, the use of the Clarke sign as a routine part of a knee examination is not beneficial, and its use should be discontinued.
authors.affiliation: University of Wisconsin-La Crosse, La Crosse, WI 54601, USA. doberste.scot@uwlax.edu
authors.forename: Scott T
authors.initials: ST
authors.lastname: Doberstein
authors.forename: Richard L
authors.initials: RL
authors.lastname: Romeyn
authors.forename: David M
authors.initials: DM
authors.lastname: Reineke
mesh_terms: D000328:Adult; D018771:Arthralgia / Q000175:diagnosis* / Q000503:physiopathology; D046789:Chondromalacia Patellae / Q000175:diagnosis* / Q000503:physiopathology; D005080:Exercise Test; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis* / Q000503:physiopathology; D007719:Knee Joint / Q000473:pathology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology