Diagnostic Value of Magnetic Resonance Imaging in Detecting Meniscus Injuries Keeping Arthroscopy as Gold Standard

Abstract

Objective: To determine the diagnostic accuracy of magnetic resonance imaging (MRI) for detecting meniscal injuries in patients with knee trauma, using arthroscopy as the reference standard. Study design and setting: Cross-sectional validation study conducted in the Department of Radiology, PAEC General Hospital, Islamabad. Methodology: Using non-probability consecutive sampling, 143 patients aged 18–70 years with clinically suspected meniscal injury after knee trauma within the preceding two months were enrolled. All participants underwent knee MRI on a 1.5-T scanner with a dedicated knee coil, followed by arthroscopy. MRI findings were compared with arthroscopic findings, and a 2×2 contingency table was used to calculate sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy. Results: The mean age was 36.8±12.4 years; 94 patients (65.7%) were male, and the right knee was involved in 82 (57.3%). Arthroscopy demonstrated a meniscal tear in 105 patients (73.4%), whereas MRI demonstrated a tear in 104 (72.7%). Overall, MRI yielded 97 true-positive, 31 true-negative, 7 false-positive, and 8 false-negative results. Sensitivity was 92.4%, specificity 81.6%, PPV 93.3%, NPV 79.5%, and overall diagnostic accuracy 89.5%. Conclusion: MRI demonstrated high diagnostic accuracy for meniscal injuries and is a useful non-invasive preoperative diagnostic modality. Arthroscopy remains the reference standard, particularly when persistent mechanical symptoms or therapeutic intervention require direct intra-articular assessment.