Mcmurray Test: Purpose, Test Details & Results

Purpose of Mcmurray Test

The McMurray test remains a cornerstone in the clinical evaluation of knee injuries, especially when a meniscal tear is suspected. Though simple to perform in the clinic, its interpretation can be nuanced and dependent on many factors, including examiner experience and patient history. This section introduces why the McMurray test is used, when clinicians choose it, and its role in the broader context of knee assessment.

Why the McMurray Test is Used

The McMurray test is designed to detect tears of the meniscus—the C-shaped cartilage in the knee that cushions and stabilizes the joint. Meniscal tears are among the most common knee injuries, often resulting from trauma, twisting motions, or degeneration over time 8.

• Primary Goal: The test aims to elicit symptoms (pain, clicking, or a palpable thud) that are characteristic of meniscal injury.
• Clinical Setting: It’s typically used during the physical examination of patients with knee pain, swelling, or mechanical symptoms such as locking or catching.

When is the McMurray Test Appropriate?

The test is most useful when the clinical history and initial examination already point toward a possible meniscal injury. It is not recommended as a universal screening tool for all knee complaints, as indiscriminate use can increase false positives 5. Its value is highest in patients whose symptoms and risk factors make a meniscal tear likely.

The McMurray Test in Diagnostic Strategy

• Complementary Tool: It is rarely used in isolation. The McMurray test is often combined with other assessments, such as joint line tenderness and imaging modalities like MRI or arthroscopy, to increase diagnostic accuracy 2,4,8.
• Clinical Decision-Making: A positive McMurray test can prompt further investigation, such as diagnostic arthroscopy. A negative result, however, does not rule out a meniscal tear due to the test’s limited sensitivity 4.

Limitations of Purpose

While the McMurray test is widely used, studies consistently show that it has relatively low sensitivity but high specificity. In practice, this means that while a positive test is fairly reliable for confirming a meniscal tear, a negative test does not reliably exclude it 2,3,4,5.

Mcmurray Test Details

Performing and interpreting the McMurray test requires both technical skill and an understanding of its nuances. This section explores how the test is done, what constitutes a positive result, and what factors can influence the findings.

Technique: How the McMurray Test is Performed

The classic McMurray test is performed with the patient lying supine:

1. Flex the Knee: The examiner bends the knee fully.
2. Rotation:
   • To test the medial meniscus, the examiner externally rotates the foot and tibia.
   • To test the lateral meniscus, the examiner internally rotates the foot and tibia.
3. Extension: While maintaining rotation, the examiner straightens (extends) the knee.
4. Palpation: The examiner feels and listens for a palpable "thud," click, or pain along the joint line 1,5,6.

Interpreting a Positive Test

• Positive Findings: A palpable or audible click, thud, or pain along the joint line during the maneuver is considered a positive sign, suggesting a meniscal tear.
  • Medial Meniscus: Thud or click on the medial joint line with external rotation 1,6.
  • Lateral Meniscus: Symptoms on the lateral side with internal rotation 6.
• Variants and Paradoxical Signs: Some tears can produce atypical findings, such as pain in the medial compartment with internal rotation, or vice versa, due to specific tear patterns 6.

Modifications and Variations

• Several modified versions of the McMurray test have been proposed to improve its diagnostic accuracy. These modifications involve changes in knee positioning, rotation, or the addition of valgus/varus stress 2.
• Some studies suggest that these modified maneuvers may enhance sensitivity and diagnostic value compared to the traditional test 2.

Factors Influencing Results

Examiner Experience

• Experience Matters: Interobserver reliability is moderate; more experienced clinicians tend to produce more consistent results 1,4.
• Standardization is Key: Variability in how the test is performed and interpreted can affect diagnostic accuracy 2,4.

Patient Factors

• Chronicity and Severity: The test may be less sensitive in chronic or complex tears.
• Other Knee Pathology: Swelling, pain, or restricted range of motion can interfere with the test.

Clinical Context

• The test is most informative when the pre-test probability (likelihood of a tear based on history and symptoms) is moderate to high 5. Using the test indiscriminately in patients with low likelihood of meniscal injury increases the risk of false positives.

Limitations of the McMurray Test Technique

• Incomplete Sensitivity: Not all meniscal tears will produce a positive test, especially small or degenerative tears 2,4,5.
• False Positives: Other conditions, such as loose bodies or osteoarthritis, can also produce joint line clicks or pain 5.

Mcmurray Test Results & Follow-Up

Understanding what the results of the McMurray test mean—and what to do next—is crucial for optimal patient care. This section discusses test accuracy, what a positive or negative result implies, and how the findings influence next steps in management.

Diagnostic Accuracy: Sensitivity and Specificity

• Sensitivity: Ranges from very low (16%) to moderate (58%). This means a significant portion of meniscal tears will NOT be detected by the test, especially smaller or complex tears 1,3,4,5,8.
• Specificity: Consistently high (79-98%). A positive test is reliable—most patients with a positive McMurray test do indeed have a meniscal tear 1,3,4,5,8.
• Positive Predictive Value: A positive test substantially increases the likelihood of a tear, especially in patients with a high pre-test probability based on history and symptoms 1,4,5.
• Negative Predictive Value: A negative test does not reliably rule out a tear—further investigation may be needed 4,5,8.

What a Positive Test Means

• Clinical Action: A positive McMurray test, especially when supported by history and other findings, often leads clinicians to recommend imaging (such as MRI) or even diagnostic arthroscopy to confirm and treat the tear 4,7,8.
• Predictive Value: In experienced hands, a positive test is highly suggestive and can guide next steps in care 1,4.

What a Negative Test Means

• Do Not Exclude: Given the test’s low sensitivity, a negative result does not exclude a meniscal tear. Patients with ongoing symptoms may still require imaging or further evaluation 2,4,5,8.

Combining the McMurray Test with Other Assessments

• Joint Line Tenderness: When used in combination with the McMurray test, the overall diagnostic accuracy is slightly improved, but not dramatically 4,8.
• Modified McMurray Tests: Some newer variations may offer better sensitivity, but are not yet universally adopted 2.
• Clinical Judgment: Ultimately, test results should always be interpreted in the context of the full clinical picture—history, exam, and, when needed, imaging 2,4,5,8.

Follow-Up After the Test

1. Positive Result:

   • Strongly consider MRI or arthroscopy for confirmation and definitive management 4,7,8.
   • Discuss treatment options, which may include conservative therapy or surgical intervention depending on tear type, severity, and patient activity level.

2. Negative Result:

   • If suspicion remains, pursue further workup—especially if the patient’s symptoms persist or worsen.
   • Monitor for changes and reconsider diagnosis if new symptoms develop.

3. Special Cases:

   • Complex tears, root tears, or associated ligament injuries may require more advanced imaging and specialist referral 6,7.

Conclusion

The McMurray test has stood the test of time as a quick, office-based method for assessing meniscal injuries. However, its limitations—especially its low sensitivity—mean that it should not be used in isolation for decision-making. Here’s what to remember:

• Primary Role: Used to detect meniscal tears, especially in patients with a suggestive history and examination.
• Technique Matters: Proper performance and interpretation are crucial; examiner experience improves reliability.
• Results Interpretation:
  • Positive Test: High specificity—likely confirms a tear; further diagnostic steps are warranted.
  • Negative Test: Low sensitivity—does not rule out a tear; further evaluation may be required if suspicion remains.
• Diagnostic Strategy: Best used in combination with clinical history, other physical tests, and, when needed, imaging.
• Clinical Judgment is Essential: The McMurray test is a helpful tool, but not a standalone solution.

Key Takeaways:

• The McMurray test is best for confirming, not ruling out, meniscal tears.
• Accuracy depends on technique, clinical context, and examiner experience.
• Always interpret test results alongside patient history and other findings.
• When in doubt, advanced imaging or referral may be needed for definitive diagnosis.

By understanding both the strengths and limitations of the McMurray test, clinicians and patients alike can make more informed decisions about knee injury evaluation and management.