The role of MRI in the diagnosis of intra articular knee derangement: A prospective study

Abstract

Background: Magnetic resonance imaging (MRI) has several advantages compared with other modalities in evaluating internal derangement of the knee & it has practically replaced conventional arthrography in the evaluation of menisci & cruciate ligaments as it is non invasive, painless and give excellent soft tissue contrast.Objective: To assess the role of MRI in internal derangement of the knee.Methods: Thirty patients with suspected internal derangement of the knee were subjected to a dedicated MR knee study and correlated knee arthroscopy and surgery. MRI of the knee was performed in closed magnet (1.5 Tesla, Seimens). Arthroscopy was done within two months of MR examination and was considered gold standard for the internal derangement of the knee. Results:The sensitivity, specificity, diagnostic accuracy of MRI were 94.1%, 84.6% and 90% respectively for medial meniscal tear; 71.4%, 95.6% and 90% respectively for lateral meniscal tear and 85.7%, 91.3% and 90% respectively for anterior cruciate ligament tear. Conclusion:MRI represents the optimal imaging tool in the evaluation of internal knee derangement as it showed high sensitivity, specificity, diagnostic accuracy for meniscal and cruciate ligament injury, in addition to associated derangement like articular cartilage damage and synovial effusion. IntroductionThe knee is a complex structure and one of the most stressed joints in the body. It is a large joint, vital for movement, and susceptible to injury. Knee injuries represent roughly 6% of all acute injuries treated at emergency department and approximately one-third of these have been reported to be sports related [1]. The principal intra articular structures in knee are the two menisci, the two cruciate ligaments, and the two collateral ligaments. The injury to these intra articular structures is generally termed as " Meniscal tear and degeneration are manifested as increased signal intensity on T1 & T2 weighted images within the substance of meniscus. Meniscal abnormalities on MRI have been classified by grading system [5,6] into 4 grades as in figures 1-4. Clinical significant of intra meniscal signal uncertain, it likely that MRI is more sensitive than arthroscopy and the decision to perform menisectomy currently is based exclusively on the presence of a surface tear.The normal anterior cruciate ligament (ACL) should have a taut, low to intermediate signal intensity with continuous fibres in all planes and sequences. Tears of ACL typically occur in the middle portion of the ligament. The diagnosis of ACL tear is made on MRI by either Identifying disruption of the ligament along its normal course (figure 5) or as a focus of increased signal intensity within the substance of the ligament often best seen by T2-weighted image [7][8][9][10][11].Tears of the posterior cruciate ligament (PCL) are diagnosed by disruption along the course of the ligament or by areas of increased signal intensity within the substance of the ligament. Most of PCL tears involve the mid substance of the ligament [12,1...