What is the role of the McMurrary (McMurray) test in diagnosing meniscal tears in patients with knee pain and a history of trauma or twisting injuries?

McMurray Test for Meniscal Tears

Diagnostic Performance

The McMurray test has modest diagnostic accuracy and should not be used as a standalone test for diagnosing meniscal tears, but rather as part of a composite clinical examination that includes joint line tenderness and history of locking, followed by MRI confirmation. 1, 2, 3

Test Accuracy for Medial Meniscus

• Sensitivity: 70-80% 2, 4
• Specificity: 73-89% 2, 4
• Overall accuracy: 61-76% 2, 3
• The test performs better when combined with other clinical findings rather than used in isolation 2, 5

Test Accuracy for Lateral Meniscus

• Sensitivity: 56-69% 2, 4
• Specificity: 75-90% 2, 4
• Overall accuracy: 72-91% 2, 3
• McMurray demonstrates superior performance for lateral meniscus screening compared to medial meniscus 4

Optimal Diagnostic Algorithm

Step 1: Clinical Examination

• Perform McMurray test in combination with joint line tenderness and assess for history of locking or giving way 5
• When at least two clinical tests are positive (composite testing), diagnostic accuracy increases substantially to 85% for medial meniscus and 92% for lateral meniscus 2
• McMurray test combined with locking and giving way achieves 80% predicted correct percentage for meniscal tears 5

Step 2: Imaging Confirmation

• Obtain plain radiographs first if patient meets Ottawa knee rule criteria (focal tenderness, effusion, inability to bear weight) to exclude fractures 1, 6
• Proceed to MRI as the definitive diagnostic test, which has 96% sensitivity and 97% specificity for meniscal tears 1, 6
• In patients under 40 years with knee effusion >10mm on lateral radiograph, proceed directly to MRI 1, 6
• MRI changes management from surgical to conservative in up to 48% of patients with locked knee 6, 7

Step 3: Combined Interpretation

• Combining McMurray test, locking, and MRI increases diagnostic accuracy to 89-92% 5
• The combination of clinical tests and MRI provides the most precise diagnosis for surgical planning 2, 5

Important Clinical Considerations

Timing of Examination

• Perform clinical examination 4-5 days post-injury for optimal accuracy, not immediately after trauma 1
• The Lachman test (for ACL evaluation) achieves 84% sensitivity and 96% specificity when performed at this interval 1

Confounding Factors

• McMurray test results are significantly influenced by perimeniscal synovitis in degenerative meniscus tears 8
• Larger synovial area (OR=1.106) and higher histologic synovitis score (OR=2.595) independently predict positive McMurray test results 8
• In osteoarthritic knees, a positive McMurray test may reflect inflammatory synovitis rather than mechanical tear characteristics 8

Age-Related Pitfalls

• In patients over 70 years, the majority have asymptomatic meniscal tears 6
• MRI findings must be correlated with clinical symptoms in elderly patients, as detection of tears does not necessarily indicate clinical significance 6
• In patients 45-55 years, the likelihood of meniscal tear is similar in both painful and asymptomatic knees 6

Alternative Imaging When MRI Unavailable

• Ultrasound is the first-line alternative with 88% sensitivity and 90% specificity for meniscal tears 1, 6
• Ultrasound performs best for recent injuries (<1 month) with 86% specificity 6
• Joint effusion on ultrasound has 91% positive predictive value for internal derangement 1, 6
• CT has limited utility with lower sensitivity than MRI for soft tissue evaluation, though it shows high specificity when meniscal tears are apparent 9

Key Clinical Pitfalls to Avoid

• Do not rely on McMurray test alone - it has only 38-62% sensitivity in isolation and requires composite testing 8, 5
• Do not skip initial radiographs in acute trauma - they guide subsequent imaging decisions and detect fractures 1, 6
• Do not perform clinical examination immediately after injury - wait 4-5 days for optimal accuracy 1
• Do not order MR arthrography or MRA routinely - they are not indicated for initial meniscal tear diagnosis 1, 6, 7
• Do not interpret positive McMurray test in isolation in degenerative knees - consider perimeniscal synovitis as a confounding factor 8