The McMurray test is a common maneuver performed during a physical examination of the knee joint. Healthcare professionals, such as orthopedists and physical therapists, use this diagnostic tool to assess the integrity of the menisci, the C-shaped cartilage structures cushioning the knee. It functions as a preliminary screening method to help determine the source of a patient’s knee pain, catching, or mechanical symptoms.
How the McMurray Test is Performed
The McMurray test involves the manipulation of the knee joint to intentionally stress the meniscal tissue. The patient lies supine while the examiner first flexes the knee and hip completely, bringing the heel toward the buttock. This initial position loads the posterior horns of the menisci, which are the most common sites for tears. The provider then controls the ankle and applies a specific rotational force to the lower leg while simultaneously moving the knee from full flexion toward extension.
This rotational and extension movement is designed to trap any potentially torn or loose fragments of the meniscal cartilage between the bones of the thigh and shin. The provider applies slight pressure, often with a valgus or varus force, as the knee is straightened to increase the compression on the cartilage. The test is considered positive if the maneuver produces a distinct, painful click, an audible pop, or if it reproduces the patient’s familiar joint-line pain or catching sensation.
What a Positive McMurray Test Indicates
A positive McMurray test strongly suggests a tear in one of the knee menisci. The location of the suspected tear can often be differentiated based on the specific direction of leg rotation performed during the maneuver. To test the medial meniscus (inner side of the knee), the examiner externally rotates the lower leg while extending the knee. Conversely, to assess the lateral meniscus (outer side of the knee), the examiner internally rotates the lower leg while extending the knee. A painful click or pop during external rotation points toward a medial meniscal tear, while the same symptom during internal rotation suggests a lateral meniscal tear.
The McMurray test is a clinical sign and not a definitive diagnosis. Diagnostic accuracy varies widely; the test often shows high specificity (a positive result indicates a true tear) but lower sensitivity (a negative result does not reliably rule out a tear). For instance, the test is more accurate for lateral meniscus tears (sometimes over 90% accuracy) compared to medial meniscus tears (around 60% accuracy). False-positive results can occur due to other conditions, such as perimeniscal inflammation in patients with knee osteoarthritis, meaning the test must be interpreted alongside a full clinical history.
Confirmatory Tests and Treatment Overview
Following a positive McMurray test, the next steps involve confirming the diagnosis and determining the extent of the injury. The initial imaging step involves standard X-rays of the knee to rule out bony pathology, such as fractures or advanced osteoarthritis. While X-rays cannot visualize the meniscal cartilage, they provide a necessary structural overview of the joint.
Imaging Confirmation
The primary confirmatory imaging modality is Magnetic Resonance Imaging (MRI), which provides detailed visualization of the menisci and surrounding soft tissues. MRI is highly accurate for meniscal tears, often showing a sensitivity of over 90% for medial tears and high specificity for lateral tears. This scan allows the physician to assess the tear’s size, pattern, and location, and identify associated injuries like ligament damage or cartilage wear.
Treatment Options
Treatment pathways are determined by the tear’s severity, the patient’s age, and their activity level. For minor, stable tears or degenerative tears in older patients, the initial approach is often conservative, focusing on non-surgical management. This includes:
- Rest, ice, compression, elevation (RICE).
- Non-steroidal anti-inflammatory drugs (NSAIDs) for pain control.
- A supervised physical therapy program.
This conservative approach aims to strengthen the muscles surrounding the knee and restore joint function. Surgical intervention is typically reserved for larger, unstable tears that cause persistent mechanical symptoms like locking or catching, or tears that fail to improve with conservative treatment. The most common surgical procedure is arthroscopy, a minimally invasive technique where a tiny camera is inserted into the joint. During arthroscopy, the surgeon may perform a meniscal repair (sewing the torn pieces back together) or a partial meniscectomy (trimming away the unstable, damaged tissue). The decision to repair or remove tissue depends on the tear’s location and the blood supply available to the specific meniscal zone.