McMurray Test is Most Likely to be Positive in This Patient
The McMurray test is most likely to be positive in this 62-year-old man with medial knee pain and tenderness at the medial joint line, as these findings strongly suggest a medial meniscal tear.
Clinical Presentation Analysis
The patient presents with:
- 2-week history of medial left knee pain and swelling
- Onset after stumbling during a long run
- Subsiding swelling
- No preexisting knee conditions
- Physical findings of:
- Slight bony prominence on both sides of the left knee
- Tender point at the medial joint line immediately posterior to the patella
Diagnostic Test Rationale
McMurray Test
- Specifically designed to detect meniscal tears
- The patient's presentation with medial joint line tenderness is highly suggestive of a medial meniscus injury
- Recent research shows McMurray test has a diagnostic accuracy of 61.2% for medial meniscus tears 1
- When combined with joint line tenderness, the diagnostic value increases significantly
Other Tests Comparison
Anterior Drawer Test
- Primarily tests anterior cruciate ligament (ACL) integrity
- Not specifically indicated for isolated meniscal injuries without clinical instability
- ACR guidelines indicate this test is more appropriate for ligamentous injuries 2
Apley Distraction Test
- Tests for ligamentous injuries rather than meniscal tears
- Less sensitive than McMurray for meniscal pathology
Fibular Compression Test
- Not a standard test for meniscal injuries
- More relevant for fibular head or lateral compartment issues
Valgus Stress Test
- Evaluates medial collateral ligament integrity
- Not specific for meniscal pathology
Evidence-Based Reasoning
The combination of medial joint line tenderness and a history consistent with meniscal injury strongly supports a positive McMurray test. Studies show that:
- McMurray test has a specificity of 79% for diagnosing medial meniscus tears 3
- Joint line tenderness combined with McMurray test increases diagnostic accuracy 4
- The mechanism of injury (stumbling during running) is consistent with a twisting injury that commonly causes meniscal tears 5
Common Pitfalls to Avoid
- Failing to perform the McMurray test correctly (requires full flexion followed by extension with rotation)
- Misinterpreting pain during the test as a positive finding (a positive test requires a palpable or audible click)
- Not considering that acute swelling may limit the test's sensitivity initially
- Overlooking that the test is more accurate when performed 3-5 days after injury when acute pain has subsided
Conclusion
Based on the patient's presentation with medial knee pain, joint line tenderness, and mechanism of injury, the McMurray test is most likely to be positive, indicating a medial meniscus tear. If clinical suspicion remains high despite negative initial testing, MRI would be the next appropriate imaging study to evaluate for internal derangement as recommended by ACR guidelines 2.