What is the diagnosis and treatment for a patient presenting with a positive McMurray sign?

Positive McMurray Sign: Diagnosis and Management

Primary Diagnosis

A positive McMurray sign indicates a meniscal tear of the knee, most commonly affecting the medial meniscus. 1 The test demonstrates modest diagnostic accuracy with sensitivity ranging from 38-62% and specificity of approximately 79% for medial meniscus tears. 2, 3

Clinical Interpretation

Understanding Test Results

• McMurray test accuracy varies by meniscus location: The test shows 61.2% accuracy for medial meniscus tears and 91.5% accuracy for lateral meniscus tears. 1
• The test should not be used in isolation: When applied individually, McMurray's test has limited diagnostic value and should be combined with joint line tenderness and clinical history. 3
• Perimeniscal synovitis influences results: In patients with knee osteoarthritis, a positive McMurray sign may be influenced by perimeniscal inflammation rather than the tear itself, with larger synovial area (OR=1.106) and higher synovitis scores (OR=2.595) being independent predictors of test positivity. 2

Paradoxical Findings

• Atypical McMurray results occur in 12% of cases: Pain or clicking may occur in unexpected compartments due to anteriorly based posterior oblique tears, bucket-handle tears in the posterior meniscus, or peripheral detachment of discoid menisci. 4

Diagnostic Workup

Imaging Studies

• MRI is the primary imaging modality: Order knee MRI to confirm meniscal pathology, assess tear pattern, and evaluate for associated injuries including ligamentous damage and bone bruising. 5
• Plain radiographs should be obtained: X-rays help exclude osteoarthritis, fractures, and other bony pathology that may influence treatment decisions. 5

Arthroscopy Confirmation

• Arthroscopy remains the gold standard: When surgical intervention is being considered, arthroscopy provides definitive diagnosis and allows simultaneous treatment. 1, 3

Treatment Algorithm

For Patients WITHOUT Osteoarthritis

Non-surgical management should be attempted first in patients without mechanical locking, significant instability, or high athletic demands:

• Activity modification and supervised rehabilitation program for 6-12 weeks 5
• NSAIDs for pain control
• Physical therapy focusing on quadriceps strengthening and range of motion

Surgical intervention (arthroscopic meniscectomy or repair) is indicated when:

• Persistent mechanical symptoms (locking, catching) despite 6-12 weeks of conservative treatment 5
• Patient participates in cutting and pivoting sports and desires return to activity 5
• Large, displaced tears causing functional limitation
• Repairable tear patterns in younger patients (<40 years) 5

For Patients WITH Osteoarthritis

Positive McMurray sign predicts favorable arthroscopic outcomes in osteoarthritic knees when the clinical findings align with radiological evidence of meniscal pathology. 6

Arthroscopic meniscectomy is appropriate when:

• McMurray sign is positive AND correlates with MRI findings of meniscal tear 6
• Mechanical symptoms are present (not just pain alone)
• Conservative management has failed after 3-6 months
• Patient has reasonable cartilage preservation (not end-stage arthritis)

Avoid arthroscopic surgery when:

• McMurray sign is positive but MRI shows minimal meniscal pathology (likely synovitis-driven symptoms) 2
• Severe tricompartmental osteoarthritis is present (consider arthroplasty instead)
• Symptoms are primarily pain without mechanical features

Critical Pitfalls to Avoid

• Do not rely solely on McMurray test: The test has only 54% sensitivity for medial meniscus tears and should be combined with joint line tenderness, patient history, and imaging. 3
• Consider synovitis as a confounding factor: In degenerative meniscus tears with osteoarthritis, perimeniscal inflammation may cause positive McMurray signs independent of tear severity. 2
• Recognize paradoxical findings: Pain in the medial compartment with internal rotation or lateral compartment with external rotation may indicate atypical tear patterns requiring careful arthroscopic evaluation. 4
• Avoid unnecessary surgery in osteoarthritis: Arthroscopic meniscectomy should only be performed when mechanical symptoms clearly correlate with imaging findings, as outcomes are poor when driven primarily by synovitis. 2, 6