Diagnostic Efficacy of Magnetic Resonance Imaging in Evaluation of Injured Knee

Objectives: To correlate outcome of clinical assessment, radiographic and MRI (magnetic resonance imaging) findings with operative results. To recommend some approaches in diagnostic evaluation of injured knee. Study design: Comparative diagnostic study. Setting: Study was conducted in the Department of Diagnostic Radiology, Shaikh Zayed Postgraduate Medical Institute, Lahore. Duration of study: From January 2005 to August 2005. Patients and methods: Fifty patients (41 males and 9 females) were included in this study with clinical suspicion of internal derangement in injured knee. Clinical assessment, plain x-ray and MRI findings were recorded in each patient. Reports of surgical findings were collected in all cases. A correlation between clinical, plain x-ray and MRI findings with surgical findings was made in each case. Results: Plain x-ray had very limited role in evaluation of soft tissue injury of knee. Clinical assessment raised suspicion of some internal derangement but failed to detect precise lesion. There was no significant difference between MRI and surgical findings. MRI was found to have sensitivity of 92%, specificity of 50% and accuracy of 89.28% for depiction of ACL (anterior cruciate ligament) injury. It had a sensitivity of 89.28%, specificity of 66.67% and accuracy of 87.09% for detection of meniscal tear. It had an overall sensitivity of 93.18%, specificity of 16.67% and accuracy of 84% for depiction of internal derangement. Conclusions: Magnetic resonance imaging is far superior to plain x-ray and better than clinical assessment and has a high sensitivity, accuracy and positive predictive value.