Bethany Uphold Casagranda DO, Presenter: Nothing to Disclose

Emad Almusa DO, Abstract Co-Author: Nothing to Disclose

David H. Kim MD, Abstract Co-Author: Nothing to Disclose

Derek R. Armfield MD, Abstract Co-Author: Nothing to Disclose

Jeffrey Dalton Towers MD, Abstract Co-Author: Nothing to Disclose

Douglas D. Robertson, Abstract Co-Author: Nothing to Disclose

Meniscal root tears are a newly recognized pathology that can be visualized with MRI. They are associated with spontaneous osteonecrosis, acl tears, and subchondral stress reactions. No validated MRI criteria exists for grading root tears. The purpose of this study to measure the accuracy and reliability of a MRI grading system which defined the root as intact, partially torn, or completely torn.

Sixteen previously MRI-diagnosed cases of posterior meniscal root tears were selected. Seven of these patients had operative reports. Five additional MRI studies from individuals with arthroscopically-proven intact roots and torn medial meniscus bodies were selected as controls. All MR imaging exams were retrospectively reviewed by 2 musculoskeletal radiologists who had not previously seen the studies. Femoral condyles were obscured so no secondary clues were visible. Each observer blindly reviewed each case twice, with each session separated by at least 4 weeks. Posterior root grade (intact, partial tear, complete tear) as well as meniscal extrusion were recorded.

Based on operative reports 5 posterior roots were intact, 3 partially torn, and 4 completely torn. The interobserver Kappa coefficients for the two grading sessions were 0.65 and 0.71 respectively. The intraobserver Kappa coefficients were 0.67 and 0.73. Kappa coefficients for observers’ agreement with operative findings ranged from 0.68 to 0.75. Interobserver reliability and classification accuracy improved with the second grading session. All complete root tears had meniscal extrusion greater than 3.3 mm. Root tear presence was not associated with age, BMI, gender, or knee sidedness.

Posterior meniscal roots tears can be accurately and reliably detected with MR imaging. Transection of meniscal continuity (complete root tear) produces meniscal extrusion greater than 3 mm. This finding agrees with other studies measuring extrusion and complete radial tears. Meniscal dyfunctional produces seriousness consequences and as radiologists we should be aware of root tears and excessive meniscal extrusion.

Casagranda, B, Almusa, E, Kim, D, Armfield, D, Towers, J, Robertson, D, Validity of Knee MRI Meniscal Root Grading.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4417294.html