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. 2018 Apr 9;6(4):2325967118765722.
doi: 10.1177/2325967118765722. eCollection 2018 Apr.

High Rate of Missed Lateral Meniscus Posterior Root Tears on Preoperative Magnetic Resonance Imaging

Aaron J Krych  1 , Isabella T Wu  1 , Vishal S Desai  1 , Naveen S Murthy  2 , Mark S Collins  2 , Daniel B F Saris  1   3 , Bruce A Levy  1 , Michael J Stuart  1
Affiliations

High Rate of Missed Lateral Meniscus Posterior Root Tears on Preoperative Magnetic Resonance Imaging

Aaron J Krych et al. Orthop J Sports Med. .

Abstract

Background: Lateral meniscus posterior root tears (LMPRTs), if left untreated, can cause devastating effects to the knee, with rapid articular cartilage degeneration and loss of the meniscus as a secondary stabilizer. Detection and surgical repair of these defects have been linked to favorable outcomes, but preoperative identification of LMPRTs continues to be challenging.

Purpose: To determine the rate of LMPRTs diagnosed preoperatively on magnetic resonance imaging (MRI) in a consecutive series of arthroscopically confirmed LMPRTs.

Study design: Case series; Level of evidence, 4.

Methods: A retrospective cohort of 45 consecutive patients with arthroscopically confirmed LMPRTs between 2010 and 2017 were included in this study. The preoperative MRI report for each patient was evaluated and compared with intraoperative findings. Each preoperative MRI study was then reviewed by 2 fellowship-trained musculoskeletal radiologists who worked in consensus.

Results: A total of 45 patients (32 males, 13 females) with arthroscopically confirmed LMPRTs and a mean age of 27 years (range, 14-54 years) were included in the study. Only 15 of 45 LMPRTs (33%) were initially diagnosed on preoperative MRI. Past or concurrent anterior cruciate ligament (ACL) reconstruction was present in 37 of 45 cases (82%). Upon retrospective review, 15 of the 30 missed LMPRTs were "clearly evident," 12 "subtly evident," and 3 "occult" (unavoidably missed). There were no significant differences in the rate of LMPRT diagnosis based on history of prior knee surgery, meniscus extrusion, or tearing of the meniscofemoral ligament.

Conclusion: Despite improved identification of other meniscus tear patterns on MRI, a high percentage of LMPRTs were still missed. In the setting of previous ACL reconstruction, if the root cannot be confidently identified, the MRI interpretation should indicate that "the root is poorly visualized" to alert the surgeon to thoroughly evaluate this structure. The surgeon should maintain a high index of suspicion and carefully probe the posterior root of the lateral meniscus at the time of arthroscopy, especially in cases of ACL injury.

Keywords: lateral meniscus; magnetic resonance imaging; meniscus root; meniscus root tear.

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Conflict of interest statement

One or more of the authors has declared the following potential conflict of interest or source of funding: A.J.K. receives research support from Aesculap/B. Braun, the Arthritis Foundation, Ceterix, and Histogenics; is a paid consultant for Arthrex and Vericel; and is on the board of the Musculoskeletal Transplant Foundation. D.B.F.S. receives research support from Arthrex, Ivy Sports, and Smith & Nephew and is a paid consultant for Cartiheal, Smith & Nephew, and Vericel. B.A.L. receives royalties from Arthrex; is paid consultant for Arthrex and Smith & Nephew; and receives research support from Arthrex, Biomet, Smith & Nephew, and Stryker. M.J.S. is a paid consultant for Arthrex, receives royalties from Arthrex, and receives research support from Stryker.

Figures

Figure 1.
Figure 1.
Arthroscopic images of the lateral meniscus (LM) of the right knee in 2 patients. (A) LM viewed through the anterolateral portal, with the probe in the anteromedial portal, has an intact root (star) attached to the tibia. (B) Same view as panel A but in a different patient, demonstrating an LM posterior root tear (arrow) evident only when the probe is used to lift and inspect the LM root.
Figure 2.
Figure 2.
(A) Coronal T2-weighted magnetic resonance image of the left knee of a 16-year-old girl shows a “clearly evident” lateral meniscus posterior root tear (circled), as diagnosed on preoperative imaging and later confirmed (B) arthroscopically (arrow).
Figure 3.
Figure 3.
Sequential coronal T2-weighted magnetic resonance images—(A) more posterior and (B) more anterior—of the left knee of a 33-year-old man demonstrate subtle irregularity and intermediate signal within an attenuated posterior root lateral meniscus (arrows). This tear was characterized as “subtly evident” by the reviewers. (C) The same meniscus tear (arrows) on subsequent arthroscopic examination.
Figure 4.
Figure 4.
Twenty-seven-year-old woman with a history of multiple knee surgical procedures. T2-weighted magnetic resonance imaging demonstrated an “occult,” or unavoidably missed, tear (circled), even in consensus retrospective review of the (A) coronal and (B) sagittal views. (C) The patient was diagnosed with a lateral meniscus posterior root tear (arrow) during arthroscopic revision lateral meniscus repair.
See this image and copyright information in PMC

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