Using the McMurray Test to Diagnose Knee Injuries and ACL Tears

Introduction

Knee injuries are among the most common reasons people seek medical attention, especially those who play sports or lead active lifestyles. Of all the possible knee injuries , meniscal tears and anterior cruciate ligament (ACL) ruptures occur frequently and require accurate diagnosis for proper care. The McMurray test—a classic knee examination technique—is often used to detect meniscal injuries. But what happens if someone also has an ACL tear? Can the McMurray test still provide reliable information, or does it become less dependable? In this article, we look at the complexities of using the McMurray test when ACL injuries are present and explain why a comprehensive approach is so important for getting the diagnosis right.

What Is the McMurray Test and How Does It Work?

The McMurray test is a hands-on exam performed by a healthcare provider to check for meniscal tears inside the knee. During the test, the examiner bends the knee and rotates the lower leg both inward and outward while straightening the knee. A “positive” McMurray test occurs when this motion results in a distinct click, a sensation of catching, or pain—signs that suggest a meniscal injury.

Although this test has been a mainstay in knee exams for years, its accuracy isn’t perfect. Research has shown that the McMurray test is quite specific (it’s good at confirming a tear when it finds one), but it’s not particularly sensitive and can miss many true meniscal injuries . For example, one study found a sensitivity of 58.5% and a specificity of 93.4%, meaning it can rule in a tear but not reliably rule one out. Sometimes, it may even show a “positive” result because of other knee issues , not just meniscal damage. Of note, only a ‘thud’ felt on the medial (inner) part of the knee was strongly linked to an actual meniscus tear —with very high specificity (98%) but low sensitivity (16%), meaning it rarely occurs but is quite meaningful when it does. These findings show the strengths and clear limitations of the McMurray test. Essentially, it should be used as one piece of the puzzle, not as the sole method of diagnosis .

Why ACL Tears Complicate the Diagnosis

Things get trickier when a patient has an ACL tear in addition to (or instead of) a meniscal injury. The ACL is crucial for knee stability , and if it’s torn, the knee can become “loose” or unstable. This instability can change the way the joint moves, which sometimes masks or mimics the symptoms usually detected during the McMurray test. That means a damaged ACL could either hide a meniscal tear or make a healthy meniscus seem injured.

The situation gets even more complicated when unusual symptoms appear. For example, research has documented that sometimes the pain or clicking appears on the opposite side of the knee than expected, especially with certain types of meniscus tears . These “paradoxical” findings can make diagnosis much more challenging, especially if both the meniscus and ACL are injured.

Interestingly, examiner experience does not always guarantee an accurate result. Even skilled clinicians may miss or misinterpret what they feel or hear during the McMurray test, especially when more than one injury is present.

That’s why clinicians rarely rely on the McMurray test alone when an ACL injury is suspected. Other physical examinations—like the Lachman test and the anterior drawer test—are specifically designed to detect ACL tears . For example, with the Lachman test, the clinician gently pulls the lower leg forward; excessive movement compared to the other knee strongly points to an ACL tear. Using a combination of these tests makes for a more accurate diagnosis, allowing the examiner to distinguish between meniscal and ACL injuries or to identify if both exist.

A Combined Approach: Physical Exams and Imaging

Relying solely on the McMurray test when an ACL tear might be present can lead to missed or delayed diagnoses, which can affect a patient’s treatment plan and recovery. That’s why clinicians use a combination of physical tests and, when available, imaging studies like magnetic resonance imaging (MRI). MRI is especially helpful because it shows detailed images of the soft tissues, making it much easier to identify tears in the meniscus , ACL, or both.

When MRI is not available right away, a thorough physical exam using several different tests remains the best option. If the McMurray test is positive, it should trigger further investigation, rather than being taken as proof on its own. This approach helps ensure that patients get the right diagnosis and the treatment they need.

Conclusion

The McMurray test remains a valuable tool for detecting meniscal injuries , but its limitations become especially clear when ACL tears are in the picture. Since an ACL injury can change knee stability and the way the joint moves, a positive McMurray test does not always provide the full answer. To avoid mistakes, healthcare professionals should always use multiple clinical tests along with imaging when possible. This comprehensive approach leads to more accurate diagnoses and better results for patients who have complex knee injuries . As research progresses, our ability to diagnose and treat these problems will continue to improve, helping more people get back to an active life.