The McMurray Test is a standardized clinical examination technique used by healthcare professionals to detect a tear in the menisci of the knee joint. Named after British orthopedic surgeon Thomas Porter McMurray, the test involves the controlled movement of the knee through flexion and extension while simultaneously applying rotational forces. It is a dynamic assessment that aims to reproduce symptoms by intentionally trapping a torn flap of the meniscus between the femur and tibia. This physical examination is a common preliminary step in evaluating a patient presenting with mechanical knee symptoms.
Preparing the Patient and Examiner Stance
The patient must be positioned lying face-up, or supine, on an examination table. The hip and knee of the leg being tested are fully flexed, bringing the heel close to the buttock. Patient relaxation is important, as muscle guarding can interfere with the accurate application of stress during the test.
The examiner adopts a stance that allows for maximum control and leverage over the patient’s lower leg. One hand firmly grasps the patient’s heel or ankle to control the rotation of the lower leg. The other hand is placed over the knee joint, with the thumb and fingers positioned along the medial and lateral joint lines. This hand stabilizes the knee and allows the examiner to palpate for any mechanical changes during the movement.
Maneuver for Assessing the Medial Meniscus
The mechanics for assessing the medial meniscus are designed to compress the inner fibrocartilage structure, particularly the posterior horn. The test begins with the knee in maximal flexion, typically ninety degrees or more. To target the medial meniscus, the examiner first applies an external rotation to the tibia by turning the foot outward.
While maintaining this outward rotation, the examiner applies a valgus stress, which pushes the knee inward toward the midline. This combination narrows the medial compartment, effectively loading the medial meniscus. The examiner then slowly extends the knee from its fully flexed position, generally stopping around ninety degrees of flexion.
This slow extension movement, maintained under constant external rotation and valgus stress, causes a potentially torn segment of the medial meniscus to be caught between the femoral condyle and the tibial plateau. The examiner focuses on feeling for any abnormal mechanical response along the medial joint line during this extension arc. A deliberate motion is necessary to ensure the posterior and middle segments of the medial meniscus are adequately tested.
Maneuver for Assessing the Lateral Meniscus
The technique used to assess the lateral meniscus is the opposite of the medial maneuver, aiming to compress the outer fibrocartilage structure. Starting with the knee in maximal flexion, the examiner applies an internal rotation to the tibia by turning the foot inward.
Simultaneously with the internal rotation, the examiner applies a varus stress, which pushes the knee outward away from the midline of the body. This combination narrows the lateral compartment, thereby loading the lateral meniscus. The examiner then smoothly extends the knee from full flexion toward ninety degrees, keeping the internal rotation and varus stress constant throughout the movement.
This motion forces a potentially damaged portion of the lateral meniscus to be compressed between the lateral femoral condyle and the lateral tibial plateau. The hand stabilizing the knee is focused on palpating the lateral joint line for any mechanical sign of obstruction during the extension arc. The controlled application of internal rotation and varus stress is essential for isolating the posterior and middle segments of the lateral meniscus.
Interpreting the Test Results
A positive McMurray test is defined by a distinct mechanical event occurring during the controlled extension phase. This event is typically an audible or palpable click, snap, or clunk felt along the joint line. This mechanical sensation is often accompanied by the patient reporting sharp pain, or a feeling of the knee “catching” or “locking.”
The location of the positive finding correlates with the side of the meniscus that is likely torn. A click and pain during the external rotation and valgus stress maneuver suggests a tear in the medial meniscus. Conversely, a positive sign during the internal rotation and varus stress maneuver indicates a potential tear in the lateral meniscus. While a positive result suggests meniscal pathology, the test has variable accuracy and is not definitive alone. It is used in conjunction with other clinical tests and is often followed by advanced imaging, such as magnetic resonance imaging (MRI), to confirm the diagnosis.