The McMurray test is a common physical examination maneuver used to assess potential issues within the knee joint. This non-invasive procedure serves as a diagnostic tool, providing insights into the knee’s internal structures. It is typically performed in a clinical setting, often as a preliminary step when a patient presents with knee pain or after an injury.
Purpose of the McMurray Test
The McMurray test primarily identifies potential injuries within the knee joint, specifically suspected meniscal tears. The meniscus is a C-shaped piece of cartilage that acts as a shock absorber between the thigh bone (femur) and the shin bone (tibia), providing cushioning and stability to the knee joint. Menisci can tear when the knee experiences sudden twisting or forceful rotation.
This test helps healthcare providers understand if symptoms like pain, swelling, or reduced motion might be related to a meniscal injury. While it can indicate a potential tear, it is not a definitive diagnostic tool on its own.
How the Test is Performed
To perform the McMurray test, the patient lies on their back with the affected knee fully flexed. The examiner stands on the side of the injured knee, placing one hand on the patient’s heel and the other on the knee joint, allowing the examiner to feel for abnormalities.
The examiner manipulates the patient’s leg by applying specific rotations and pressure while slowly extending the knee from its fully flexed position. To assess the medial meniscus (inner side of the knee), the tibia is externally rotated with valgus stress (pressure applied to the outside of the knee, pushing inward) as the knee extends. For the lateral meniscus (outer side of the knee), the tibia is internally rotated with varus stress (pressure applied to the inside of the knee, pushing outward) during extension. Throughout these movements, the examiner listens and feels for clicks, pops, or grinding sensations, and observes for any pain reported by the patient. This maneuver aims to compress a potentially torn portion of the meniscus between the femur and tibia, reproducing symptoms.
Interpreting the Findings
Interpreting the McMurray test involves recognizing specific signs during the maneuver. A “positive” test occurs when the examiner hears or feels a distinct click, pop, or thud, or when the patient experiences pain during the rotational and extension movements. A painful click during outward rotation and valgus stress often suggests a medial meniscus tear, while a painful click during inward rotation and varus stress may indicate a lateral meniscus tear. These findings suggest a potential meniscal tear, as the maneuver causes the torn cartilage to catch between the bones.
A “negative” test means the examiner did not feel or hear any clicking, popping, or experience any pain. However, a negative result does not definitively rule out a meniscal tear. The test’s diagnostic accuracy varies, and false positives or negatives can occur. Factors like high muscle tone or significant swelling can influence the outcome. Therefore, the McMurray test is considered one piece of a broader diagnostic process, not a standalone diagnosis.
Next Steps After the Test
Following a McMurray test, especially if positive, healthcare providers typically recommend further diagnostic procedures to confirm the initial findings. Imaging tests are commonly used to assess the extent of internal knee injury. Magnetic Resonance Imaging (MRI) is often the preferred imaging modality, providing detailed pictures of the knee’s soft tissues, including the menisci. X-rays or ultrasounds may also be used to provide additional information or rule out other issues.
If the diagnosis remains unclear or surgical intervention is considered, a knee arthroscopy may be performed. This minimally invasive procedure involves inserting a tiny camera into the knee joint to directly visualize the damage. Results from these tests, combined with physical examination findings, help guide treatment decisions. These can range from conservative management like rest, pain relievers, and physical therapy, to surgical repair or removal of damaged meniscal tissue.