McMurray Test: Procedure, Interpretation, and Clinical Significance

How to perform McMurray test?

The McMurray test is a clinical orthopedic maneuver utilized to assess for tears of the menisci within the knee joint, involving specific knee movements and rotational stresses to elicit pain or a palpable click.

Understanding the McMurray Test

The McMurray test is a widely recognized special test in orthopedic and physical therapy examinations, primarily used to identify tears in the medial or lateral menisci of the knee. Developed by Thomas P. McMurray, this provocative test aims to reproduce the symptoms of a meniscal tear by trapping the injured meniscus between the femoral condyles and the tibial plateau, thereby eliciting pain, a palpable click, or a clunk. It is a key component of a comprehensive knee examination, complementing patient history and other physical assessments.

Anatomy Involved

To understand the McMurray test, it's crucial to recall the anatomy of the knee joint, specifically the menisci:

• Menisci: These are two C-shaped, fibrocartilaginous pads located between the femoral condyles and the tibial plateau.
  • Medial Meniscus: Larger, more C-shaped, and less mobile, it is more commonly injured due to its attachment to the medial collateral ligament.
  • Lateral Meniscus: Smaller, more O-shaped, and more mobile, making it less frequently injured than its medial counterpart.
• Function: Both menisci act as shock absorbers, distribute joint load, provide joint stability, and aid in joint lubrication.
• Mechanism of Injury: Meniscal tears often result from twisting injuries to the knee, especially when the foot is planted, or from degenerative changes over time.

Indications for Performance

The McMurray test is typically performed when a meniscal injury is suspected. Common indications include:

• Acute Knee Pain: Especially following a twisting injury.
• Clicking or Popping Sensations: Within the knee joint during movement.
• Knee Locking or Catching: The sensation that the knee is getting stuck or cannot fully extend.
• Swelling: While not specific, swelling can accompany meniscal tears.
• Joint Line Tenderness: Pain upon palpation along the medial or lateral joint line.

Contraindications and Precautions

While generally safe, certain situations warrant caution or contraindicate the use of the McMurray test:

• Acute Trauma with Suspected Fracture: Do not perform if a fracture is suspected until ruled out.
• Severe Pain: If the patient is in severe pain, aggressive testing may exacerbate their discomfort.
• Joint Instability: Exercise caution in cases of significant ligamentous laxity.
• Recent Surgery: Avoid if it could compromise surgical repair.

Always perform the test gently and stop if the patient experiences excruciating pain. Communication with the patient throughout the process is paramount.

Equipment Needed

The McMurray test requires minimal equipment:

• Examination Table: To allow the patient to lie supine comfortably.
• Gloves: Recommended for hygiene during physical examination.

Step-by-Step Procedure: Lateral Meniscus Assessment

This variation of the McMurray test specifically targets the lateral meniscus.

• Patient Positioning: The patient lies supine on the examination table.
• Examiner Positioning: The examiner stands on the side of the knee to be tested.
  • The examiner grasps the patient's heel with one hand, controlling the foot and ankle to facilitate tibial rotation.
  • The other hand is placed on the patient's knee, specifically along the lateral joint line, with the thumb and fingers positioned to palpate for clicks or assess for pain.
• Execution Steps:
  1. Full Knee Flexion: Gently flex the patient's knee fully, bringing the heel towards the buttocks.
  2. Internal Tibial Rotation: Apply maximal internal rotation to the tibia by rotating the foot inwards.
  3. Valgus Stress Application: While maintaining internal rotation, apply a gentle valgus stress (force applied to the outside of the knee, pushing inwards) to the knee.
  4. Slow Knee Extension: Slowly and smoothly extend the knee from full flexion towards approximately 90 degrees or until resistance is met, maintaining internal rotation and valgus stress throughout the movement.
• Positive Test Interpretation: A positive test for a lateral meniscal tear is indicated by the reproduction of the patient's pain, a palpable or audible click/clunk, or a sensation of the knee "giving way" as the knee is extended. This typically occurs as the torn lateral meniscus is trapped between the lateral femoral condyle and the lateral tibial plateau.

Step-by-Step Procedure: Medial Meniscus Assessment

This variation of the McMurray test specifically targets the medial meniscus.

• Patient Positioning: The patient lies supine on the examination table.
• Examiner Positioning: The examiner stands on the side of the knee to be tested.
  • The examiner grasps the patient's heel with one hand, controlling the foot and ankle to facilitate tibial rotation.
  • The other hand is placed on the patient's knee, specifically along the medial joint line, with the thumb and fingers positioned to palpate for clicks or assess for pain.
• Execution Steps:
  1. Full Knee Flexion: Gently flex the patient's knee fully, bringing the heel towards the buttocks.
  2. External Tibial Rotation: Apply maximal external rotation to the tibia by rotating the foot outwards.
  3. Varus Stress Application: While maintaining external rotation, apply a gentle varus stress (force applied to the inside of the knee, pushing outwards) to the knee.
  4. Slow Knee Extension: Slowly and smoothly extend the knee from full flexion towards approximately 90 degrees or until resistance is met, maintaining external rotation and varus stress throughout the movement.
• Positive Test Interpretation: A positive test for a medial meniscal tear is indicated by the reproduction of the patient's pain, a palpable or audible click/clunk, or a sensation of the knee "giving way" as the knee is extended. This typically occurs as the torn medial meniscus is trapped between the medial femoral condyle and the medial tibial plateau.

Interpreting Results and Clinical Significance

A positive McMurray test suggests the presence of a meniscal tear, but it is not definitive on its own.

• Consider Clinical Picture: The results must always be correlated with the patient's history (mechanism of injury, symptoms), other findings from the physical examination (e.g., joint line tenderness, effusion, range of motion limitations), and, if necessary, diagnostic imaging (e.g., MRI).
• Specificity and Sensitivity: The McMurray test has varying sensitivity and specificity depending on the study, but it is generally considered to have good specificity (meaning a positive result is more likely to indicate a true tear) but lower sensitivity (meaning a negative result does not definitively rule out a tear).

Limitations of the McMurray Test

Despite its widespread use, the McMurray test has several limitations:

• False Positives: Other knee pathologies, such as osteochondral defects or plica syndrome, can sometimes produce similar clicks or pain, leading to a false positive.
• False Negatives: Small or stable tears may not be provoked by the test, leading to a false negative.
• Patient Tolerance: If the patient is experiencing significant pain or guarding, it may be difficult to perform the test adequately.
• Examiner Skill: The accuracy of the test can be influenced by the examiner's experience and technique.

Important Considerations for Practitioners

For fitness professionals, coaches, or student kinesiologists, understanding the McMurray test is valuable for:

• Client Assessment: Recognizing when a client's symptoms warrant referral to a medical professional.
• Injury Recognition: Developing a foundational understanding of common knee injuries and their assessment.
• Scope of Practice: Emphasizing that performing this test for diagnostic purposes is within the scope of practice for licensed medical professionals (e.g., physicians, physical therapists), not typically for fitness trainers. The knowledge serves to inform, not to diagnose.
• Patient Communication: Being able to explain why certain movements might be painful or why a medical referral is necessary.

When to Seek Professional Medical Advice

If you or someone you are working with experiences knee pain, clicking, locking, or instability, especially after an injury, it is crucial to:

• Consult a Healthcare Professional: Seek evaluation from a qualified physician, physical therapist, or orthopedic specialist.
• Avoid Self-Diagnosis: Special tests like the McMurray test are part of a comprehensive diagnostic process and should not be used for self-diagnosis.
• Follow Medical Recommendations: Adhere to any recommended imaging (e.g., MRI) or treatment plans.