What is the test for knee assessment?

From the Guidelines

The most appropriate initial test for knee evaluation is a combination of physical examinations and imaging studies, with X-rays being the first-line imaging modality, as recommended by the American College of Radiology 1. When evaluating a patient with knee symptoms, such as pain, swelling, or locking, a thorough physical examination should be performed to assess knee function and identify potential injuries or conditions. The physical examination should include tests such as the anterior drawer test for ACL integrity, the McMurray test for meniscal tears, the valgus/varus stress tests for collateral ligament stability, and the patella apprehension test for patellar instability.

For imaging, X-rays are typically ordered first to evaluate bone structure and alignment, as they are highly specific for detecting fractures and other bony abnormalities 1. However, if the X-rays are negative, an MRI may be ordered to provide detailed visualization of soft tissues, including ligaments, tendons, and cartilage 1. MRI has been shown to be highly sensitive and specific for detecting meniscal tears, ACL injuries, and other soft-tissue injuries, and can help guide treatment decisions.

Some key points to consider when evaluating the knee include:

• The Ottawa rule criteria, which can help determine the need for imaging studies 1
• The presence of knee effusion, which can indicate a significant injury 1
• The mechanism of injury, which can help guide the physical examination and imaging studies
• The patient's symptoms and medical history, which can help inform the diagnosis and treatment plan

Overall, a combination of physical examinations and imaging studies, with X-rays as the first-line imaging modality, is the most appropriate approach for evaluating the knee, as it allows for a thorough assessment of knee function and identification of potential injuries or conditions. The use of MRI can be particularly useful in cases where the X-rays are negative, but the patient's symptoms and physical examination suggest a significant soft-tissue injury 1.

From the Research

Tests for Knee Injuries

• The Lachman test is highly sensitive and specific for detecting anterior cruciate ligament (ACL) tears 2, 3, 4, 5, 6
• The posterior drawer test is sensitive and specific for posterior cruciate ligament tears, and its accuracy can be enhanced with other tests such as the posterior sag sign 2
• The McMurray test is specific but has low sensitivity for meniscal tears, while joint line tenderness has fairly good sensitivity but lacks specificity 2
• Collateral ligament testing seems to be sensitive and specific, but there is a lack of well-designed studies to scientifically validate its sensitivity and specificity 2

Diagnostic Accuracy of Clinical Tests

• The diagnostic accuracy of the Lachman test, anterior drawer test, and pivot shift test for ACL tears has been reported in several studies, with varying results 3, 4, 5, 6
• A systematic review and meta-analysis found that the Lachman test, anterior drawer test, and pivot shift test have comparable diagnostic accuracy for ACL tears, but the Lachman test may have been overestimated in previous studies 5
• The pivot shift test is highly specific for diagnosing ACL laxity, especially under anesthesia 6
• The McMurray test is not a sensitive test for diagnosing meniscal injury in the presence of ACL injury 6

Comparison of Tests

• The Lachman test and anterior drawer test have been compared in several studies, with some finding that the Lachman test is more sensitive 3, 4
• The lever test has been found to have lower sensitivity and specificity compared to the Lachman test and anterior drawer test 3
• The pivot shift test has been found to be highly specific for diagnosing ACL laxity, especially under anesthesia 6