A characteristic MRI finding to diagnose a partial tear of the medial meniscus posterior root: an ocarina sign

Abstract

Background Diagnosing partial tears of the medial meniscus (MM) posterior root is difficult. The aim of this study was to evaluate diagnostic values involved in conventional magnetic resonance imaging (MRI) features of MM posterior root tears (MMPRTs) and find other MRI-based findings in patients with partial MMPRTs. Methods Eighteen patients who had arthroscopically confirmed partial MMPRTs were included. As a control, 18 patients who underwent partial meniscectomy for other types of MM tears were evaluated. Isolated partial MMPRTs were classified into the following three types: type A, accurate partial stable tear (cleavage < 1/2 of root width); type B, bridged unstable root tear (cleavage ≥ 1/2 of root width); type C, complex horn tear expanded to the root. Conventional MRI-based findings of MMPRTs were evaluated between two groups (n = 23). Posterior root irregularity, bone marrow spot, and ocarina-like appearance showing several condensed circles in triangular meniscal horn (ocarina sign) were also evaluated. Results Posterior root irregularity and bone marrow spot were frequently observed in the partial MMPRTs (47.8%), compared with the other MM tears (P = 0.007 and 0.023, respectively). The ocarina sign was detected in 69.6% of patients with partial MMPRTs. A significant difference between two groups was observed in a positive ratio of ocarina sign (P < 0.001). Types A, B, and C of the partial tear/damage were observed in three, eight, and seven patients, respectively. The ocarina sign was the most common MRI finding in each type of partial MMPRT. Conclusions This study demonstrated that a characteristic MRI finding, “ocarina sign,” was frequently observed in patients with partial tear/damage of the MM posterior root. The ocarina sign was the most common MRI finding in several types of partial MMPRTs. Our results suggest that the ocarina sign may be useful to diagnose unnoticed partial MMPRTs. Level of evidence: IV, retrospective comparative study.

The clinical and radiographic outcomes of type 2 medial meniscus posterior root tears following transtibial pullout repair

“…An MRI evaluation was performed using Achieva 1.5 T (Philips, Amsterdam, the Netherlands) with a knee coil, as previously reported [6]. The MRI‐based MME was defined as the distance from the medial margin of the tibial plateau to the outer border of the MM that crossed the midpoint of the anteroposterior length of the MM.…”

Clinical evaluation of suture materials for transtibial pullout repair of medial meniscus posterior root tear

“…Thus, untreated MMPRT may lead to rapid osteoarthritis progression in the knee joint’s medial compartment [ 3 , 4 ]. As prior research has indicated that MMPRTs are biomechanically equivalent to total medial meniscectomy [ 5 ], accurate diagnosis and early repair are essential for subsequent treatment [ 6 ]. Several techniques have been introduced for MMPRT repair; transtibial pullout repair is frequently performed, as it does not require posterior portals, whereas trans-osseous drilling may enhance meniscal healing through stem-cell recruitment from the bone marrow [ 7 , 8 ].…”

Rehabilitation after Repair of Medial Meniscus Posterior Root Tears: A Systematic Review of the Literature

“…The interest in medial meniscus posterior root tears (MMPRTs) has been growing. MMPRTs, which are defined as radial tears or avulsion injuries on bony attachments, 1 2 3) result in decreased contact surface and increased peak pressure through a loss of hoop tension due to circumferential fiber disruption. 4 5 6) MMPRTs can result in complications after total meniscectomy, with pathologic loads leading to degenerative arthritis.…”