Hidden Meniscus Problems: Ramp Lesion and Posterior Meniscus Medial Root Tear

Ramp lesion (RL) is a peripheral tear affecting the posterior horn of the medial meniscus in the setting of ACL tears. Posterior meniscus medial root tear (PMMRT) is defined as an avulsion of the attachment, or a complete radial tear within 1 cm of the posterior tibial attachments of the meniscus. Both are not uncommonly found. The prevalence of RL existing in conjunction with ACL tears ranges from 9 to 42%. On the other hand, PMMRT contributes up to 10 to 21% of all meniscus tears. Both RL and PMMRT have significant consequences. RT increases anterior tibia translation and internal rotation after ACL reconstruction which may increase graft failure. PMMRT may accelerate the progress of medial knee osteoarthritis. Unfortunately, both conditions are frequently overlooked from physical examination, MRI reading, and arthroscopy procedures, due to the low sensitivity, unfamiliarity, and hidden location of the lesions. Posteromedial tibia edema finding on MRI images in a complete ACL tear in young patients increases the risks of RL. Ghost sign and medial femorotibial edema found on MRI may indicate PMMRT. RL and PMMRT may not be identifiable from the standard arthroscopic view. The trochlear view may be needed for RL and MCL trephination is almost always needed for PMMRT. The stability of both lesions should be assessed by meniscus probing, and repair is the gold standard for unstable lesions. RL can be repaired with sutures from the anterior or posterior. PMMRT is usually repaired using the transtibial pull-out suture technique.