Sooho Bae MD, Presenter: Nothing to Disclose

Sang-Hee Choi MD, Abstract Co-Author: Nothing to Disclose

Jin Hwan Ahn MD, Abstract Co-Author: Nothing to Disclose

Hye Won Chung, Abstract Co-Author: Nothing to Disclose

Young Cheol Yoon MD, Abstract Co-Author: Nothing to Disclose

Root ligament transection (RLT) means a tear of meniscus at its posterior tibial attachment site. Preoperative diagnosis of RLT is important for operation planning. The purpose of this study was to explain MR findings of RLT on knee MRI.

After approval from the investigational review board at our institution, the medical records and knee MRI of 293 patients who were reported as RLT by MR findings between January 2000 and March 2005 were obtained. Among them, 48 patients were surgically confirmed as RLT of medial meniscus (MM). Two radiologists retrospectively reviewed the three planes of MR images by consensus. Thirty cases had all MR imaging planes, but 18 cases did not have axial planes (AP) and another one, coronal plane (CP). The points used for imaging analysis were linear high signal intensity (HSI) representing tear of root ligament, regional HSI representing fluid collection, and subluxation of MM (more than 3 mm gap) on AP, linear HSI representing tear of root ligament and subluxation of MM (more than 3 mm extrusion) on CP, and abrupt disruption of medial meniscus posterior horn (MMPH) at just medial to posterior cruciate ligament (PCL) on sagittal image (SP). The sensitivities of these MR findings were calculated.

Twenty-six linear HSI (26/30), 29 regional fluid collection (29/30), one neither (1/30) findings were showed on AP. Subluxation of MM on AP was showed in 19 cases (19/30). The sensitivities of linear HSI, fluid collection, and subluxation of MM were 86.7%, 96.7%, and 63.3% respectively on AP. Forty-three linear HSI (43/47) and 44 subluxation of MM (44/47) were showed on CP. The sensitivities of linear HSI and subluxation of MM were 91.5% and 93.6% respectively on CP. Forty-seven cases (47/48) showed abrupt disruption of MMPH at medial to PCL on SP. The sensitivity of abrupt disruption was 97.9% on SP.

MR findings of RLT were HSI of root ligament, regional HSI representing fluid collection, subluxation of MM, and abrupt disruption of MMPH at medial to PCL. RLT of MM can be diagnosed preoperatively when these characteristic findings were observed on all planes of knee MRI.

Bae, S, Choi, S, Ahn, J, Chung, H, Yoon, Y, Root Ligament Transection of Medial Meniscus: MR Findings of Arthroscopically Confirmed 48 Cases.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4411932.html