The McMurray test is a common physical examination used by healthcare professionals to assess knee injuries. This diagnostic tool helps identify potential issues causing pain or instability. It serves as an initial step in understanding a patient’s knee condition.
Purpose of the Test
The McMurray test is primarily employed to detect tears in the menisci, which are C-shaped pieces of tough, rubbery fibrocartilage located within the knee joint. Each knee contains two menisci, one on the inner side (medial meniscus) and one on the outer side (lateral meniscus). These structures function as shock absorbers, distributing weight evenly across the knee joint and providing stability.
Meniscal tears are common injuries from sudden knee twisting, often seen in athletes. They can also develop gradually in older individuals due to degenerative changes. Identifying these tears with tests like the McMurray helps clinicians determine if further imaging studies, such as an MRI, or other interventions are necessary for a comprehensive diagnosis and treatment plan.
Performing the McMurray Test
A healthcare professional performs the McMurray test with the patient lying on their back. The examiner begins by fully flexing the patient’s knee and hip. One hand is placed along the knee joint line to feel for any abnormal movements, while the other hand holds the patient’s foot.
To assess different parts of the meniscus, the examiner rotates the lower leg. Internal rotation of the tibia with stress examines the lateral meniscus, while external rotation evaluates the medial meniscus. During these rotational movements, the knee is slowly extended from its fully flexed position. The test requires a skilled examiner to properly perform the maneuvers and interpret the knee joint’s responses.
Understanding the Test Results
A “positive” McMurray test result typically involves the patient experiencing a click, pop, snap, thud, or pain during the maneuver. This sensation or sound suggests that a torn piece of meniscus may be catching between the thighbone and shinbone as the knee moves. Such a finding indicates a high likelihood of a meniscal tear.
A “negative” result means there is no click, pop, or pain elicited during the test. While a positive result points to a probable meniscal injury, the McMurray test is not definitive on its own. Its accuracy, including sensitivity and specificity, can vary depending on the specific tear and methodology, with reported sensitivities ranging from 16-70% and specificities from 59-97%. Results are considered alongside the patient’s medical history, other physical examination findings, and often confirmed with imaging studies like magnetic resonance imaging (MRI) for a complete diagnosis.