The McMurray Test is a specific maneuver used during a physical examination to help determine if a tear exists in one of the menisci of the knee joint. The menisci are two C-shaped pieces of cartilage that act as shock absorbers and stabilizers between the femur and the tibia. When a healthcare professional suspects a meniscal injury, this test is performed as part of a clinical evaluation. The technique is designed to reproduce the mechanical stress that causes a torn piece of cartilage to become pinched between the joint surfaces.
Pre-Test Positioning and Setup
The test begins with the patient lying flat on their back (supine). The healthcare provider stands on the same side as the injured knee to gain optimal leverage and control over the leg. This positioning allows the examiner to move the knee through its full range of motion.
The examiner uses one hand to stabilize the knee at the joint line, placing the thumb and fingers along the medial and lateral sides to feel for movement or clicking. The other hand firmly holds the patient’s heel or ankle. The knee is brought into a position of full flexion, with the heel pulled close to the buttocks.
Executing the Medial Meniscus Assessment
To assess the medial meniscus (the cartilage on the inside of the knee), a precise sequence of movements is executed. The examiner first applies a rotational force to the lower leg by turning the foot outward, resulting in external rotation of the tibia. This maneuver positions the medial meniscus to be loaded during the next phase.
While maintaining this external rotation, the examiner applies a valgus stress, which is a gentle force pushing the knee inward toward the midline. Keeping both the external rotation and the valgus stress constant, the knee is slowly extended from full flexion toward a 90-degree angle. This extension under stress causes the femur to roll over the externally rotated tibia, mechanically compressing the posterior portion of the medial meniscus. The examiner listens and feels for a distinct click or clunk along the medial joint line during this controlled extension.
Executing the Lateral Meniscus Assessment
Assessing the lateral meniscus (the cartilage on the outside of the knee) requires a mirrored set of maneuvers. Starting with the knee in full flexion, the examiner internally rotates the tibia by turning the foot inward. This rotation prepares the lateral meniscus for compression.
A varus stress is then applied, involving a gentle force pushing the knee outward away from the midline. With the internal rotation and varus stress held steady, the examiner slowly extends the knee. This controlled movement causes the femur to roll over the internally rotated tibia, compressing the posterior horn of the lateral meniscus. The examiner’s hand on the joint line feels and listens for a click or clunk along the lateral side during this extension.
Understanding a Positive Result and Clinical Relevance
A positive McMurray Test is indicated by a palpable or audible click, thud, or clunk within the knee joint during the extension phase, often accompanied by pain. The location of the mechanical symptom suggests which meniscus is involved: external rotation points toward the medial meniscus, while internal rotation points toward the lateral meniscus. The click occurs because a torn fragment of the meniscus is momentarily caught between the femur and tibia, snapping out of place as the knee straightens.
The McMurray Test is a diagnostic tool, not a definitive diagnosis. Its accuracy varies widely, with reported specificities ranging from 59% to 97% and sensitivities from 16% to 70% across different studies. While a positive result is helpful, it is not consistently reliable at confirming a tear, and a negative result does not completely rule one out.
A positive result suggests the likelihood of a meniscal tear, prompting the need for further diagnostic steps. To confirm the tear and determine its size and location, the professional correlates the test findings with the patient’s history, other physical examination results, and advanced imaging like Magnetic Resonance Imaging (MRI). The McMurray Test is performed only by qualified healthcare providers, such as physicians or physical therapists, and should never be attempted for self-diagnosis.