Alice La Marra MD, Presenter: Nothing to Disclose

Silvia Mariani MD, Abstract Co-Author: Nothing to Disclose

Lorenzo Maria Gregori, Abstract Co-Author: Nothing to Disclose

Lucia Patriarca, Abstract Co-Author: Nothing to Disclose

Antonio Barile MD, Abstract Co-Author: Nothing to Disclose

Carlo Masciocchi MD, Abstract Co-Author: Nothing to Disclose

To determine prospectively the role of 1.5 T, dedicated low-field standard and upright-MRI in the evaluation of stable or unstable traumatic tears of medial meniscus in comparison with arthroscopy.

Our series included 3500 knee MRI scans performed with a high field MRI scanner from January 2010 to March 2014. On the basis of the concordance between clinical and high-field MRI diagnosis, we selected two groups . In the first group (group A) we included 70 MRI exams of normal knee and in the second group (group B) we included 275 MRI exams of knee with clinical evidence of medial meniscus traumatic lesions. In the same session, after conventional 1.5T and “dedicated” 0.25T supine MRI exam, the patients underwent upright weight-bearing examination with the same dedicated MRI unit. We used sagittal and coronal scans ( SE T1-W) in all cases. All 275 patients were submitted to arthroscopy between 7 and 21 days after diagnostic examination.

In group A, there were no statistically significant anatomical changes of the signal intensity, position and morphology of the medial meniscus between standard 1.5T, dedicated supine and upright MRI. In group B, the images acquired in the supine position (dedicated and 1.5T MRI) documented, in 32 cases (group B1) a meniscocapsular separation, in 106 cases (group B2) a longitudinal lesion, in 67 cases (group B3) horizontal lesion and in 70 cases a radial tear (group B4). In group B1, weight-bearing MRI showed presence of unstable tear in 32 out of 32 cases. In group B2, weight-bearing MRI showed presence of unstable tear in 89 out of 106 cases. In group B3, weight-bearing MRI showed an unstable meniscal tear in 45 out of 67 cases. In group B4, weight-bearing MRI showed an unstable meniscal tear in 45 out of 70 cases. Arthroscopy confirmed weight-bearing MRI diagnosis in all cases of Group B1, B2 and B3; in group B4 arthroscopy showed unstable tear in 65 out of 70 cases (20 cases of WB-MRI false negative).

The upright MRI allows to record load-induced physiological variation, thus showing both the meniscal stability and a latent instability only for meniscocapsular separations, longitudinal and horizontal medial meniscal tears.

The knowledge of an unstable medial meniscal tear is very useful to correctly guide the orthopedic surgeon towards an appropriate surgical treatment.

La Marra, A, Mariani, S, Gregori, L, Patriarca, L, Barile, A, Masciocchi, C, Functional Evaluation of Traumatic Tears of the Medial Meniscus of the Knee using Weight-bearing MRI.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010326.html