Medial Meniscus Posterior Root Tear: How Far Have We Come and What Remains?

Abstract

Medial meniscus posterior root tears (MMRTs), defined as tears or avulsions that occur within 1 cm of the tibial attachment of the medial meniscus posterior root, lead to biomechanically detrimental knee conditions by creating a functionally meniscal-deficient status. Given their biomechanical significance, MMRTs have recently been gaining increasing interest. Accordingly, numerous studies have been conducted on the anatomy, biomechanics, clinical features, diagnosis, and treatment of MMRTs, and extensive knowledge has been accumulated. Although a consensus has not yet been reached on several issues, such as surgical indications, surgical techniques, and rehabilitation protocols, this article aimed to comprehensively review the current knowledge on MMRTs and to introduce the author's treatment strategies.

Keywords: medial meniscus posterior root; medial meniscus posterior root tear; meniscus root; meniscus root repair; root tear; transtibial pull-out repair.

Figure 1

(A) An illustration showing the medial meniscus posterior root and its surrounding anatomical structures. (B) The occurrence of a medial meniscus posterior root tear leads to the loss of hoop tension in the meniscus, resulting in meniscus extrusion. PCL: posterior cruciate ligament; MMPR: medial meniscus posterior root; MTE: medial tibial eminence; MMRT: medial meniscus posterior root tear; ACL: anterior cruciate ligament.

Figure 2

Characteristic magnetic resonance imaging findings, suggestive of a medial meniscus posterior root tear. (A) Vertical high signal on the coronal image (truncation or cleft sign; white arrow). (B) Vertical high signal on the axial image (white arrow). (C) Loss of identifiable medial meniscus posterior root on the sagittal image (ghost sign; white arrow). (D) Meniscus extrusion on the coronal image (the length of the white arrow).

Figure 3

Flowchart of authors’ treatment strategies for medial meniscus posterior root tear. K-L: Kellgren-Lawrence.

Figure 4

The process of arthroscopic transtibial pull-out repair of a medial meniscus posterior root tear (MMRT). (A,B) MMRT is confirmed, and a modified reverse Mason-Allen stitch is made (view from the parapatellar high anterolateral portal). (C,D) After identification of the anatomical footprint of the medial meniscus posterior root and decorticating the bone bed, a transosseous tibial tunnel is created, and a wire loop is inserted into the joint (view from the posteromedial portal). (E) Suture strands are pulled out through a tibial tunnel (view from the posteromedial portal) and (F) tied (view from the parapatellar high anterolateral portal). Reprinted with permission from Ref. [74]. Copyright 2021, copyright with permission from Moon and Kim.

Figure 5

Pictorial illustration of the transtibial pull-out repair of a medial meniscus posterior root tear using a modified reverse Mason-Allen stitch. The stitch consists of the horizontal loop stitch (red thread; ultra-high molecular weight polyethylene suture [Tigerwire suture]) and the overlaid simple vertical stitch (blue thread; No. 1 PDS). Reprinted with permission from Ref. [38]. Copyright 2020, copyright with permission from Moon and Kim.