Meniscal Extrusion: A Narrative Review

Superior outcomes of pullout repairs for medial meniscus posterior root tears in partial tear compared to complete radial tear

PURPOSE

To reveal the outcomes of partial medial meniscus posterior root tears following transtibial pullout repair compared with the outcomes of complete radial meniscus posterior root tears.

MATERIALS AND METHODS

We retrospectively evaluated 15 consecutive patients (male/female, 5/10; average age, 64.4 years) who underwent transtibial pullout repair for partial medial meniscus posterior root tears and compared their results with those of 86 consecutive patients who underwent the same surgery for complete medial meniscus posterior root tears. All patients underwent second-look arthroscopy on average 1 year postoperatively, and a semi-quantitative meniscal healing score (anteroposterior width, stability, and synovial coverage, total 10 points) was evaluated. Medial meniscus extrusion was evaluated preoperatively and at second-look arthroscopy.

RESULTS

Postoperative clinical scores were not significantly different in the short term. However, second-look arthroscopy revealed a significant difference in repaired meniscal stability (partial tear; 3.3 points, complete tear; 2.3 points, p < 0.001) and total meniscal healing scores (partial tear; 8.3 points, complete tear; 7.1 points, p < 0.001). Medial meniscus extrusion progression was significantly different (partial tear; 0.4 mm, complete tear; 1.0 mm, p < 0.001).

CONCLUSION

Partial medial meniscus posterior root tears showed better meniscal healing and less medial meniscus extrusion progression following pullout repair than complete medial meniscus posterior root tears.

Open Medial Meniscotibial Ligament Repair With Concomitant Open Superficial Medial Collateral Ligament Repair With Internal Brace Augmentation

The medial collateral ligament (MCL) is the most commonly injured ligament in the knee. Historically, nonsurgical management for these injuries has been favored for a majority of grade I-III sprains, particularly femoral-based. However, when coupled with other injuries such as meniscotibial ligament tears or distal Stener type avulsion tears, early surgical management for these cases is recommended. This will allow for stabilization and protection of the meniscus in addition to preventing residual valgus laxity, especially related to more severe Stener-like avulsions of the superficial MCL that can be seen with meniscotibial ligament tears. Utilizing an open approach, meniscotibial repair with suture anchors with internal brace augmentation for the MCL repair can provide a strong final construct, and a safe and fast recovery.

Meniscal extrusion in knees with and without osteoarticular pathology: A systematic review of normative values and cut-offs for diagnostic criteria

BACKGROUND

Meniscus extrusion is crucial for the diagnosis and treatment of meniscal injury, but the literature on this topic has not yet been systematized. The purpose of this systematic review was to compare diagnostic methods and summarize the data of medial and lateral meniscal extrusion in knees with and without osteoarticular pathology.

METHODS

This systematic review was conducted according to the PRISMA 2020 statement. Searches were conducted on PubMed, EMBASE and Cochrane databases to identify studies that measured meniscal extrusion using magnetic resonance imaging (MRI) or ultrasound (US). Meniscal extrusion data was summarized as weighted mean for medial and lateral meniscus, and stratified according to the method of measurement (MRI or US) and presence of knee osteoarticular pathology.

RESULTS

A total of 26 studies were included in this review. Weighted mean values of meniscal extrusion were always higher for the medial than the lateral meniscus, regardless of the method of measurement. The medial meniscus extrusion was always higher in knees with osteoarticular pathology than those without. For the lateral meniscus extrusion, the mean values were higher in those knees without osteoarticular pathology. When classifying pathological meniscal extrusion with pre-defined cut-off values, the higher the cut-off used, the lower the percentage of knees classified as pathological meniscal extrusion.

CONCLUSIONS

The medial meniscus presents on mean higher extrusion and extrusion is higher in knees with osteoarticular pathology. Based on summary data, the most suitable cut-offs for pathological meniscal extrusion for both MRI and US seem to fall within >2 and >3 mm.

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

PURPOSE

This study's goal is to propose a straightforward classification system based on the MEI (Meniscal Extrusion Index), a measure of meniscal extrusion, that relates to various meniscal lesion patterns and has clinical and biomechanical significance. The study's secondary goal is to determine whether the standard 3 mm meniscal extrusion parameter still has value by correlating the MEI with it.

METHODS

1350 knee MRIs that were performed over the course of 2 years made up the study cohort. Following the application of inclusion and exclusion criteria, 200 of those patients were qualified to participate in the study. All the measurements examined for this study underwent an interobserver reliability test.

RESULTS

In the 1350 MRIs that were examined for this study, meniscal extrusion of any grade was present 18.9% of the time. The use of the MEI revealed three groups of patients: those with a MEI < 20%, who are likely para-physiological; those with a MEY between 20% and 40%, who are in a grey area; and those with a MEY > 40%, who have lesions that are impairing the proper meniscal function. According to the authors' findings, the percentage of meniscal extrusion did not correlate with the finite number (3 mm), making the 3 mm parameter an unreliable evaluation method.

CONCLUSIONS

This study is clinically relevant, because it proposes a simple and reproducible classification of meniscal extrusion that may aid in evaluating the severity of an extrusion and help in the diagnosis of lesions that might be difficult to identify on MRI.

LEVEL OF EVIDENCE

Level IV.

Effect of Injury to the Lateral Meniscotibial Ligament and Meniscofibular Ligament on Meniscal Extrusion: Biomechanical Evaluation of the Capsulodesis and Centralization Techniques in a Porcine Knee Model

Background

Previous biomechanical studies of the meniscotibial ligament have determined that it contributes to meniscal stability. An injury to it can cause the meniscus to extrude, and reconstruction of that ligament significantly reduces extrusion.

Purpose

To assess the biomechanical effects of sectioning the lateral meniscotibial ligament (LMTL) and the meniscofibular ligament (MFL) with respect to the radial mobility of the lateral meniscus and to evaluate the biomechanical effects of the capsulodesis and centralization techniques.

Study Design

Controlled laboratory study.

Methods

The lateral meniscus of 22 porcine knees was evaluated. They were mounted on a testing apparatus to apply muscle and ground-reaction forces. The meniscus was evaluated at 30° and 60° of knee flexion using 2 markers placed on the posterior cruciate ligament and the lateral meniscus after applying an axial compression of 200 N to the knee joint. Measurements were recorded under 5 conditions: intact lateral meniscus, injury of the LMTL, subsequent injury of the MFL, the use of the open capsulodesis technique, and the reconstruction of the LMTL and the MFL with the centralization technique.

Results

The distance between the 2 markers was significantly greater in the extrusion group (combined lesion of the LMTL and MFL) than in the intact or reconstruction groups (capsulodesis and centralization techniques; P < .001 in all cases). In the cases of load application, no significant differences were observed between the control group (intact meniscus) and the groups on which the reconstruction techniques were performed. There were also no differences when comparing the results obtained between both reconstruction techniques. In all settings, the distance between the 2 markers increased with the increase in the knee flexion angle.

Conclusion

In a porcine model, the LMTL and the MFL participated as restrictors of the radial mobility of the lateral meniscus during loading. Their injury caused a significant increase in lateral meniscal extrusion, and the centralization and the capsulodesis procedures were able to reduce extrusion.

Clinical Relevance

This study demonstrates the capacity of the LMTL and the MFL to restrict the radial mobility of the lateral meniscus during loading and how it is affected when they are injured.

Introduction of an easy-to-operate arthroscopic test in detecting and treatment of meniscal instability: "suction drift" test

OBJECTIVE

To explore the surgical guidance value of "suction drift" in osteoarticular meniscal instability.

METHODS

The clinical data of 104 patients with significant knee symptoms following surgery were retrospectively analyzed. "Suction drift" was diagnosed in both groups. Depending on the treatment, patients treated with conventional debridement were assigned to group A, and those treated by meniscus suture until the disappearance of the "suction drift" phenomenon were included in group B. All patients were followed up for a minimum of 6 months after surgery. The postoperative Visual Analogue Scale (VAS) score, Lysholm knee score and the occurrence of meniscus-related symptoms were compared between the two groups.

RESULTS

After puncture, 78 patients (75.0%) had excessive displacement of the meniscus, with 53 (67.9%) of them being followed-up for at least 6 months. Twenty-five patients in group A and twenty-eight in group B were included in the final analysis (The number of patients with "suction drift" in two groups was tested to be comparable, P>0.05). VAS score was significantly decreased and Lysholm knee score was markedly increased in both groups after treatment, with lower VAS score and higher Lysholm knee score in group B compared with group A. In addition, group A had a significantly higher incidence of meniscus-related symptoms (joint space tenderness, joint clicks, and noose sensation) than group B.

CONCLUSIONS

"Suction drift" is a quick and easy-to-operate arthroscopic test, which can not only diagnose meniscus instability due to knee osteoarthrosis-induced meniscus degeneration, but also help determine the recovery of meniscus stability after suture, and significantly relieve symptoms.

The meniscotibial ligament role in meniscal extrusion: a systematic review and meta-analysis

INTRODUCTION

The meniscotibial ligament (MTL) limits extrusion of the medial meniscus (MM). While meniscal extrusion may be detrimental to knee joint biomechanics, the role of the MTL in meniscal extrusion is debatable. We sought to perform a systematic review and meta-analysis to evaluate the role of the MTL and surgical techniques for MTL repair.

MATERIALS AND METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines we searched PubMed, Cochrane Library, and Embase for: (("Meniscotibial") OR ("Coronary") OR ("Ramp")) AND ("Extrusion"). After screening and applying eligibility criteria, data were extracted for MTL pathology types ("traumatic" ruptures or "induced" injuries) and meniscal extrusion. A meta-analysis evaluated the mean difference of extrusion between "intact" MTLs (native or repaired) and "injured" MTLs (induced or traumatic). We further performed a subgroup analysis between traumatic and induced MTL lesions.

RESULTS

This systematic review included six studies, which all evaluated MM extrusion. There were 74 knees with induced MTL injuries and 19 knees with traumatic MTL ruptures. Study designs were heterogenic and utilized three types of MTL repair procedures. The meta-analysis included 18 human knees and revealed that sectioning the MTL created a 2.92 mm [- 0.18 to 6.03] MM extrusion, while MTL repair decreased MM extrusion by - 2.11 mm [- 3.03 to - 1.21].

CONCLUSIONS

MTL injury may result in approximately 3 mm of MM extrusion, while repair of the MTL can decrease extrusion by 2 mm. Several novel surgical techniques exist to repair the MTL. However, studies reporting clinical outcomes of these various procedures are scarce.

Acute Repair of Meniscus Root Tear Partially Restores Joint Displacements as Measured With Magnetic Resonance Images and Loading in a Cadaveric Porcine Knee

The meniscus serves important load-bearing functions and protects the underlying articular cartilage. Unfortunately, meniscus tears are common and impair the ability of the meniscus to distribute loads, increasing the risk of developing osteoarthritis. Therefore, surgical repair of the meniscus is a frequently performed procedure; however, repair does not always prevent osteoarthritis. This is hypothesized to be due to altered joint loading post-injury and repair, where the functional deficit of the meniscus prevents it from performing its role of distributing forces. The objective of this study was to quantify joint kinematics in an intact joint, after a meniscus root tear, and after suture repair in cadaveric porcine knees, a frequently used in vivo model. We utilized an magnetic resonance images-compatible loading device and novel use of a T1 vibe sequence to measure meniscus and femur displacements under physiological axial loads. We found that anterior root tear led to large meniscus displacements under physiological axial loading and that suture anchor repair reduced these displacements but did not fully restore intact joint kinematics. After tear and repair, the anterior region of the meniscus moved posteriorly and medially as it was forced out of the joint space under loading, while the posterior region had small displacements as the posterior attachment acted as a hinge about which the meniscus pivoted in the axial plane. Methods from this study can be applied to assess altered joint kinematics following human knee injuries and evaluate repair strategies aimed to restore joint kinematics.

Meniscal Extrusion: Diagnosis, Etiology, and Treatment Options

PURPOSE OF REVIEW

The concept of meniscal extrusion has recently been recognized as a hallmark of meniscus dysfunction. This review examines contemporary literature regarding the pathophysiology, classification, diagnosis, treatment, and future directions for investigation regarding meniscus extrusion.

RECENT FINDINGS

Meniscus extrusion, defined as >3 mm of radial displacement of the meniscus, leads to altered knee biomechanics and accelerated knee joint degeneration. Meniscus extrusion has been associated with degenerative joint disease, posterior root and radial meniscal tears, and acute trauma. Meniscus centralization and meniscotibial ligament repair have been proposed as techniques to address meniscal extrusion with promising biomechanical, animal model, and early clinical reports. Further studies on the epidemiology of meniscus extrusion and associated long-term nonoperative outcomes will help to elucidate its role in meniscus dysfunction and resultant arthritic development. Understanding and appreciation for the anatomic attachments of the meniscus will help to inform future repair techniques. Long-term reporting on the clinical outcomes of meniscus centralization techniques will yield insights into the clinical significance of meniscus extrusion correction.

Meniscus tears treatment: The good, the bad and the ugly-patterns classification and practical guide

Over the years, several studies demonstrated the crucial role of knee menisci in joint biomechanics. As a result, save the meniscus has become the new imperative nowadays, and more and more studies addressed this topic. The huge amount of data on this topic may create confusion in those who want to approach this surgery. The aim of this review is to provide a practical guide for treatment of meniscus tears, including an overview of technical aspects, outcomes in the literature and personal tips. Taking inspiration from a famous movie directed by Sergio Leone in 1966, the authors classified meniscus tears in three categories: The good, the bad and the ugly lesions. The inclusion in each group was determined by the lesion pattern, its biomechanical effects on knee joint, the technical challenge, and prognosis. This classification is not intended to substitute the currently proposed classifications on meniscus tears but aims at offering a reader-friendly narrative review of an otherwise difficult topic. Furthermore, the authors provide a concise premise to deal with some aspects of menisci phylogeny, anatomy and biomechanics.

Lateral meniscal body extrusion is associated with MRI-defined knee structural damage progression over 4 years: Data from the osteoarthritis initiative

PURPOSE

To investigate the association of lateral meniscal body extrusion (LMBE) with OA-related knee structural damage progression over 4 years and to obtain thresholds of LMBE in predicting knee structural damage progression.

METHOD

We studied 196 subjects (67 male) with a mean age of 59.5 ± 7.9 (SD) years (range45-78 years) that were randomly selected from the Osteoarthritis Initiative. Radiological assessment was performed using the Osteoarthritis Research Society International grading system. Baseline LMBE was quantified on coronal sections of intermediate-weighted MRI sequences obtained at 3.0 T scanner. Knee structural damages were measured using the whole-organ MRI score. Linear regression analysis and binary logistic regression analysis was used to assess the correlation between LMBE and knee structural damage. ROC analysis and Youden index were used for calculating thresholds.

RESULTS

Cross-sectionally, increased LMBE was significantly associated with more severe lateral meniscal damage, patellofemoral and lateral compartment cartilage damage, and posterior cruciate ligament damage. Longitudinally, LMBE was statistically associated with progression of lateral meniscal damage, lateral compartment cartilage damage and bone marrow edema patterns, posterior cruciate ligament lesions and popliteal cysts. The thresholds of LMBE in suggesting progression of lateral meniscal lesions and lateral compartment cartilage lesions were 1.4 mm and 1.3 mm, respectively.

CONCLUSION

Baseline LMBE was associated with structural damage progression over 4 years in knees with or at risks for OA. Thresholds of 1.4 mm and 1.3 mm could be used in predicting progression over 4 years of lateral meniscal damage and lateral compartment cartilage damage, respectively.

Nonextruded Grafts Result in Better Cartilage Quality After Lateral Meniscal Allograft Transplantation: Quantitative 3-T MRI T2 Mapping

BACKGROUND

Several studies have reported that graft extrusion after meniscal allograft transplantation (MAT) is associated with deterioration of surgical outcomes. However, no study has investigated the effect of graft extrusion on the articular cartilage using objective quantitative methods.

PURPOSE/HYPOTHESIS

This study aimed to investigate the influence of graft extrusion on the chondroprotective effect of lateral MAT on knee articular cartilage. We hypothesized that MAT without graft extrusion would result in better cartilage quality than MAT with graft extrusion.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Altogether, 105 patients who underwent isolated lateral MAT were divided into the extrusion and nonextrusion groups based on postoperative 3-month magnetic resonance imaging. Quantitative T2 mapping was performed on pre- and postoperative magnetic resonance imaging at midterm follow-up (mean ± SD, 3.2 ± 0.7 years). The weightbearing area of the femoral and tibial plateau articular cartilage was divided into 6 segments (F1, F2, F3, TP1, TP2, and TP3) from the anterior to posterior direction according to the meniscal coverage area. Each segment was further segmented into superficial and deep layers for zonal analysis. Longitudinal change in cartilage T2 value was compared between the groups. Lysholm scores were used to evaluate clinical function.

RESULTS

The mean T2 value of the nonextrusion group showed a significant improvement in 14 of 18 segments after lateral MAT, whereas the extrusion group demonstrated no statistically significant change. The biochemical properties of cartilage tissue as judged by quantitative T2 mapping indicated improvement in the nonextrusion group as compared with the extrusion group in the F2, TP2, and TP3 segments overall; the deep layers of the F1, F2, and TP2 segments; and the superficial layer of the TP3 segment (P < .05).

CONCLUSION

This study shows that the nonextruded graft results in better cartilage properties of the knee joint after lateral MAT as compared with the extruded graft at midterm follow-up.

MRI evaluation of meniscal anatomy: which parameters reach the best inter-observer concordance?

Purpose

The aim of the study is to evaluate which MRI parameters achieve the best degree of inter-individual concordance in the description of meniscal fibrocartilage, regarding its morphology, signal and position.

Materials and methods

Eighty-nine knee MRIs were included in the study, retrospectively re-evaluated by three radiologists who completed a binary report (normal/abnormal) describing the meniscus signal, position relative to the tibial plateau margin and morphology. The inter-individual concordance value was calculated using Cohen's test.

Results

We obtained different inter-individual concordance values according to the parameters considered. The concordance was poor in the description of the meniscal position relative to the tibial plateau margin (average k = 0.6); the result was comparable in the description of the meniscal morphology (average k = 0.56). The best results were obtained with the meniscal signal analysis (average k = 0.8).

Conclusion

To the best of our knowledge, there are no studies in the literature assessing the concordance between multiple readers in the description of the parameters we studied. The results we obtained suggest that the most reliable parameter for describing meniscal fibrocartilage is its signal intensity, whereas morphology and position may lead to different interpretations that are not always unequivocal.

Meniscal Extrusion: A Critical Analysis Review

➢

Pathologic meniscal extrusion can compromise meniscal function, leading to increased contact forces in the tibiofemoral compartment and the acceleration of osteoarthritic changes.

➢

Extrusion is typically defined as radial displacement of ≥3 mm outside the tibial border and is best diagnosed via magnetic resonance imaging, although ultrasonography has also demonstrated encouraging diagnostic utility.

➢

Surgical management of meniscal extrusion is based on the underlying etiology, the patient's symptom profile, the preexisting health of the articular surface, and the risk of future chondral injury and osteoarthritis.

Meniscal Displacement and Loss of Load-Transmission Function After Radial Tear of the Lateral Meniscus in a Porcine Model: New Insights Into the Functional Dynamics of the Injured Meniscus

BACKGROUND

Meniscal extrusion/translation has been used as an index for meniscal treatment. However, the relationship between meniscal displacement and the degree of meniscal tear or load-transmission function of the lateral meniscus (LM) remains unclear.

PURPOSE

To clarify the relationship between the width of the radial tear of the LM and (1) meniscal displacement or (2) resultant force through the meniscus under axial compressive load in the porcine model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight intact porcine knees with or without a partial radial tear at the midbody of the LM (involving 30%, 60%, or 90% of its width) were investigated. Reflective markers were attached to the outer wall of the anterior, anteromiddle, posteromiddle, and posterior segments of the LM. A 300-N axial load was applied at 2 flexion angles (30° and 60°), and the 3-dimensional forces and trajectories of the knees were recorded. Marker movements were simultaneously tracked using a motion capture camera system. After total meniscectomy of the LM, the recorded knee trajectories were reproduced, and the resultant force through the LM was calculated (a force carried only by the meniscus in response to a load applied to the whole knee joint).

RESULTS

At both flexion angles, the change in distance (mean ± SD) between the anterior and posterior markers under load increased significantly more in the anteroposterior direction in LMs with a 90% tear than in intact LMs (30°, 0.4 ± 0.3 vs 1.4 ± 0.8 mm, P = .004; 60°, 0.1 ± 0.7 vs 1.4 ± 1.0 mm, P < .001 [intact vs 90% tear]). The change in distance between the anteromiddle and posteromiddle markers at 30° also significantly increased in LMs with a 90% tear (0.2 ± 0.2 vs 1.3 ± 1.2 mm, P = .02 [intact vs 90% tear]). The resultant force was significantly lower in LMs with a 90% tear than in intact LMs (30°, 125 ± 47 vs 48 ± 20 N, P < .001; 60°, 93 ± 46 vs 43 ± 11 N, P = .002 [intact vs 90% tear]). We found no significant differences in either meniscal displacements or resultant forces between intact LMs and those with 30% or 60% tears.

CONCLUSION

LMs with a 90%-width midbody radial tear lost load-transmission function with their displacement relative to the tibia primarily in the anteroposterior direction in the porcine model.

CLINICAL RELEVANCE

Even 1 mm of displacement after meniscal injury is evidence that the load-transmission function of the meniscus is greatly impaired. When a displaced torn LM is diagnosed in preoperative imaging, meniscal repair surgery should be considered.