The paradoxical McMurray test for the detection of meniscal tears: an arthroscopic study of mechanisms, types, and accuracy

Abstract

BACKGROUND: Meniscal tears are very common. The so-called paradoxical McMurray test has been described and found to be positive for three different types of meniscal tears. However, to our knowledge, no study has evaluated the accuracy of this test. The purpose of the present study was to evaluate the accuracy of the paradoxical McMurray test compared with the conventional McMurray test. We also sought to determine whether there are other types of meniscal tears that would show positive results on the paradoxical McMurray test.

METHODS: The authors evaluated 628 patients with meniscal tears (Group I) and 387 patients without meniscal tears (Group II), as confirmed by arthroscopy performed from June 2000 to May 2006. The results of both clinical examinations (the conventional and the paradoxical McMurray test) were recorded, and the paradoxical phenomenon as seen during arthroscopy was described. The sensitivity and specificity of each test were calculated and statistically analyzed.

RESULTS: The average patient age (and standard deviation) was 41.9 ± 15.6 years (range, ten to sixty-six years) in Group I and 40.3 ± 12.9 years (range, fifteen to sixty-three years) in Group II. The sensitivities of the McMurray test and the paradoxical McMurray test for diagnosing a meniscal tear were 41.9% (263 of 628) and 12.3% (seventy-seven of 628), respectively. The specificities of the two tests were 76.7% (297 of 387) and 99.2% (384 of 387), respectively. Compared with the conventional McMurray test, the paradoxical McMurray test showed significantly lower sensitivity but higher specificity. Apart from the three previously reported types of meniscal tears, a new type of meniscal tear in a discoid lateral meniscus also showed positive results with the paradoxical McMurray tests.

CONCLUSIONS: In conclusion, a positive paradoxical McMurray test is reliable for diagnosing a meniscal tear that has a large displaced meniscal flap. A long radial tear in the posterior one-third of the discoid lateral meniscus is a new type of meniscal tear with positive results on the paradoxical McMurray test.