Medial Meniscal Extrusion in Patients With Medial Meniscus Root Tears: A Systematic Review and Meta-analysis

Abstract

Background: Medial meniscal extrusion (MME) has received significant interest because of its correlation with medial meniscus root tears (MMRTs), its potential as a diagnostic tool, and its significance in the progression of knee osteoarthritis (OA). Purpose: To (1) evaluate if MMRTs significantly increase MME compared with nonroot tears (NRTs) and no tears and (2) determine the clinical outcomes of increased MME. Study Design: Systematic review; Level of evidence, 4. Methods: Electronic database searches of PubMed, Embase, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were conducted on June 6, 2022, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist criteria. The searches were conducted using the keywords “meniscus tear” and “extrusion.” No restrictions were placed on the date of publication. Quality and sensitivity assessments were conducted on included studies. Major MME was defined as an extrusion ≥3 mm. Results: Twenty-two studies involving 7882 knees were included. Compared with patients with NRTs, those with MMRTs had a 1.12-mm greater mean absolute meniscal extrusion (AME) and were 3.45 times more likely to have major MME ( P < .001 for both). Compared with patients with no tears, those with MMRTs had a 2.13-mm greater AME ( P < .001). Within patients with MMRT, those with widely displaced MMRT had a 1.01-mm greater AME compared with nondisplaced MMRT ( P < .001). Patients with OA had a 0.73-mm greater AME and were 3.86 times more likely to have major MME compared with patients without OA ( P < .001 for both). Within patients who were not stratified according to MMRT, NRT, or no tears, those who eventually developed OA had a 0.79-mm greater AME than those who did not have OA ( P = .02). Conclusion: Patients with MMRTs had higher MME values compared with those with other types of meniscal tears and those without any meniscal tears. Patients with knee OA were more likely to have higher MME compared with those without OA.

The meniscal extrusion index is a reliable indirect sign of different meniscal lesion patterns: a classification based on percentage of meniscal extrusion

“…In literature the presence of a meniscal lesion is often associated with meniscal extrusion [7,8,23]. Due to the anatomy of the medial meniscus, various lesions are described as more or less responsible for meniscal extrusion [9,11,18].…”

“…Due to the anatomy of the medial meniscus, various lesions are described as more or less responsible for meniscal extrusion [ 9 , 11 , 18 ].…”

“…Basing data on MRI images, without arthroscopic confirmation, may be a limitation, although knee MRI has a documented high accuracy for diagnosis of medial meniscal tear, with sensitivities of 91.8% and specificities of 80.8% [ 9 , 16 ].…”

Research interests and emerging trends of meniscal extrusion and the future of arthroscopic centralization: a bibliometric and visualized analysis in the last 20 years

“…The longstanding physiological loading after meniscus root tear increases in the tear gap, leading to meniscal extrusion [23][24][25][26] . Clinical studies indicated that patients with medial meniscus root tears had signi cantly higher meniscus extrusion compared to those without root tears, while patients with knee OA were more likely to have higher meniscus extrusion compared with those without OA [27] . Notably, the presence of meniscal root tear and subsequent meniscal extrusion are recognized as crucial risk factors for the development of knee OA, underscoring the importance of addressing meniscal extrusion to mitigate the risk of OA in patients with meniscal root tears [28] .…”

Insufficient restoration of meniscal extrusion by transtibial pullout repair for medial meniscus posterior root tears

“…A medial meniscus posterior root tear (MMPRT) is an injury to the posterior meniscal attachment of the tibia that causes abnormal knee joint kinematics. MMPRTs disrupt the hoop function and cause medial meniscus extrusion (MME) [9,25,31,34]. Conservative treatment of MMPRTs is not always efective, and meniscal repair is more efective than both partial meniscectomy and conservative treatment [4,21,22,24].…”