The diagnostic value of the Clarke sign in assessing chondromalacia patella.
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.
Doberstein
Scott T
ST
University of Wisconsin-La Crosse, La Crosse, WI 54601, USA. doberste.scot@uwlax.edu
Romeyn
Richard L
RL
Reineke
David M
DM
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