Sensitivity and specificity of magnetic resonance imaging for knee injury and clinical application for the Naresuan University Hospital.

BACKGROUND: The accuracy of MRI evaluation for the traumatic knee injury may help the physician selecting the treatment options and informing patient about the prognosis. The purpose of the present study was to analyze the result of the MRI reported from a center in Phitsanulok which would be valuable for orthopaedic surgeons who practicing in the lower northern region of Thailand.

MATERIAL AND METHOD: The 1.5 Tesla MRI of 51 injured knees that underwent subsequent arthroscopic knee surgery was independently reviewed by one from the group of radiologists. The sensitivity, specificity accuracy and negative predictive value of the MRI evaluation for menisci and cruciate ligament pathology compared to the arthroscopic finding is determined.

RESULTS: There were 50 patients with the mean age of 36.7 year old (ranging from 18-75 years) and 30 were males and 20 were females. The sensitivity, specificity accuracy and negative predictive value (NPV) in detecting the complete tear of the ACL injury were 90.9%, 84.6%, 88.6% and 84.6%, respectively. There were 100%, 97.1%, 97.5% and 100%, respectively, for diagnosis of complete PCL tear. The MRI evaluation for definite medial meniscus tear revealed 100% in sensitivity, 52.6% in specificity, 64% in accuracy and 100% in NPV. For the lateral meniscus, it yielded 55.6%, 83.3%, 75.8% and 83.3%, respectively. Among the 22 patients who underwent the ACL reconstruction without the PCL or collateral ligament injury, there was 50% of associated meniscal injury with similar ratio between medial and lateral side.

CONCLUSION: The MRI report from the center in Phitsanulok could be useful in detecting the cruciate ligament tear particularly with uncertain clinical examination. With a high negative predictive value, the MRI could be used as a negative diagnostic tool for the meniscal injury.