Sonographic evaluation of lateral meniscal extrusion: implementation and validation

A Novel Ultrasound Method of Evaluating Dynamic Extrusion of Lateral Meniscus in Healthy Population: Different Patterns of Dynamic Extrusion Revealed Between Lateral and Medial Meniscus

OBJECTIVES

To establish a reliable ultrasound (US) method of evaluating dynamic extrusion of lateral meniscus in healthy population, and to investigate the pattern of dynamic meniscus extrusion (ME) in lateral meniscus under loading conditions.

METHODS

The lateral ME was examined via US method in unloaded, double-leg standing, and single-leg standing positions. Two different US measurement methods were compared to the magnetic resonance imaging (MRI) results to determine the optimal measurement methods. The US results obtained by different researchers were tested for interobserver consistency and the results obtained by the same researcher on two separate days were tested for intraobserver consistency. The patterns of dynamic extrusion were compared between medial and lateral sides.

RESULTS

A total of healthy 44 volunteers were included in the study, with 86 knees assessed by US, and 25 knees evaluated by MRI. The US evaluation of dynamic lateral ME demonstrated excellent interobserver and intraobserver reliability. The US measurements using method A were consistent with the MRI results with no significant difference (P = .861, intraclass correlation coefficient [ICC] = 0.868), while method B underestimated the lateral ME compared to MRI (P = .001, ICC = 0.649). Lateral ME decreased slightly from unloaded (1.0 ± 0.8 mm) to single-leg standing position (0.8 ± 0.8 mm), whereas medial ME increased significantly in both double-leg and single-leg standing positions (2.4 ± 0.7 mm, 2.6 ± 0.7 mm).

CONCLUSION

A novel US evaluation method of lateral ME was established with reliable and accurate results compared to the MRI. Lateral ME in healthy populations decreased slightly as the loadings increased, which was different from the pattern of dynamic extrusion in medial meniscus.

The Role of Ultrasound in the Diagnosis and Treatment of Meniscal Injuries

PURPOSE OF REVIEW

This review evaluates the current understanding of the role of ultrasound in the diagnosis and treatment of meniscal disorders.

RECENT FINDINGS

Ultrasound (US) demonstrates similar sensitivity and specificity when compared to magnetic resonance imaging in the evaluation of meniscal injuries when compared to arthroscopy. Meniscal extrusion (ME) under US can be a reliable metric to evaluate for meniscal root tears in knees with and without osteoarthritis (OA). Sonographic ME is associated with development of OA in knees without OA. US following allograft meniscal transplant may be useful in predicting graft failure. US findings can be used to screen for discoid menisci and may demonstrate snapping of a type 3 discoid lateral meniscus. Shear wave elastography for meniscal injuries is in its infancy; however, increased meniscal stiffness may be seen with meniscal degeneration. Perimeniscal corticosteroid injections may provide short term relief from meniscal symptoms, and intrameniscal platelet-rich plasma injections appear to be safe and effective up to three years. Ultrasound-assisted meniscal surgery may increase the safety of all inside repairs near the lateral root and may assist in assessing meniscal reduction following root repair. Diagnostic US can demonstrate with high accuracy a variety of meniscal pathologies and can be considered a screening tool. Newer technologies such as shear wave elastography may allow us to evaluate characteristics of meniscal tissue that is not possible on conventional imaging. US-guided (USG) treatment of meniscal injuries is possible and may be preferable to surgery for the initial treatment of degenerative meniscal lesions. USG or US-assisted meniscal surgery is in its infancy.

Effect of inside-out meniscal repair on meniscal dimension in meniscal tear patients

Background

It remains controversial whether meniscal repair causes meniscal extrusion. This study aimed to investigate the effect of inside-out meniscal repair on meniscal dimensions in patients with meniscal tear of the mid-body-posterior horn.

Methods

This retrospective study included 75 patients who underwent meniscal repair followed by MRI within 2 weeks after surgery between 2020 and 2022. Patients with a discoid lateral meniscus, pull-out repair, concomitant osteotomy, all-inside repair only, and revision surgery were excluded. Thirty-three meniscal tear treated using an inside-out arthroscopic repair technique were included in the lateral meniscus (LM, n = 19) and medial meniscus (MM, n = 14) tear groups. Thirty-six participants with intact meniscus were included as controls. Meniscal extrusion and posterior shift were measured on coronal and sagittal MRI pre-operatively and within 2 weeks postoperatively.

Results

Preoperative coronal extrusion was significantly greater in the LM tear group than in the control group (P = 0.001). Coronal extrusion and posterior shift were significantly smaller postoperatively than preoperatively in the LM tear group (P < 0.001 and, P = 0.008, respectively). Pre- and postoperative coronal extrusion in the MM tear group were not significantly different (P = 0.291). Postoperative coronal extrusion in both LM and MM tear groups were not significantly correlated with the number of sutures required for repair (LM: P = 0.765, R = -0.076, MM: P = 0.1, R = 0.497).

Conclusions

The torn meniscus of the mid-body - posterior horn before surgery was extruded and shifted posteriorly in both LM and MM tears, and repair using an inside-out arthroscopic technique was effective in reducing meniscal extrusion and posteriors shift in the LM tear immediately after surgery.

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.

Visualization of lateral meniscus extrusion during gait using dynamic ultrasonographic evaluation

PURPOSE

Medial meniscus extrusion is one of the risk factors for knee osteoarthritis (OA). However, lateral meniscus extrusion has not been discussed, and detailed information remains unknown. In particular, the lateral meniscus has high mobility and is expected to be difficult to evaluate in terms of its behavior under static conditions. Dynamic ultrasonographic evaluation was introduced to detect the dynamic behavior of the meniscus during walking. In this study, we aimed to investigate the behavior of the lateral meniscus during walking using dynamic ultrasonographic evaluation.

METHODS

Sixteen participants with knee OA were recruited in this study. The change of lateral meniscus extrusion during walking was recorded using ultrasonography. Medial and lateral meniscal extrusion during the stance phase was measured, and meniscal mobility was defined as the difference in meniscal extrusion between minimum and maximum values (mm), medial meniscal extrusion (∆MME), and lateral meniscal extrusion (∆LME), respectively. The walking cycle and gait forms of lateral thrust were also evaluated using three-dimensional motion analysis systems and analyzed in terms of the correlation with ∆MME and ∆LME.

RESULTS

The lateral meniscus was depicted in the articular plane, and extrusion decreased during the stance phase of the gait cycle. The ∆LME was significantly higher than the ∆MME (p < 0.01). There was a significant positive correlation between ∆LME and lateral thrust (r = 0.62, p < 0.05).

CONCLUSIONS

We found that dynamic ultrasonographic evaluation can be used to visualize lateral meniscus extrusion during walking, and that its behavior is correlated to the degree of lateral thrust.

Determination of Normal Reference Values for Meniscal Extrusion Using Ultrasonography During the Different Range of Motion: A Pilot, Feasibility Study

OBJECTIVES

It is essential to know the normal extrusion measures in order to detect pathological ones. In this study, we aimed to define some normal reference values for meniscal extrusion in the normal knees during different ranges of motion.

METHODS

The amount of anterior and posterior portion of meniscal extrusion among 21 asymptomatic volunteers (42 knees) were tracked in 0, 45, and 90° of knee flexion using an ultrasound machine. The repeated measures analysis of variance (ANOVA) was used to show the interaction between the amounts of meniscal extrusion and the different degrees of knee flexion.

RESULTS

The anterior portion of the lateral menisci at full knee extension (0.59 ± 1.40) and the posterior portion of the medial menisci during 90° flexion (3.06 ± 2.36) showed the smallest and the highest mean amount of extrusion, respectively. The normal average amounts of anterior extrusion were 1.12 ± 1.17 and 0.99 ± 1.34 mm for medial and lateral menisci, respectively. The posterior meniscal normal extrusions were significantly increasing in both medial and lateral menisci during the survey (F = 20.250 and 11.298; both P values <.001) as they were measured 2.37 ± 2.16 and 1.53 ± 2.18 mm in order.

CONCLUSIONS

The medial meniscus can extrude 1.74 ± 1.84 mm normally while this amount was 1.26 ± 1.82 mm for the lateral meniscus. These measures commonly increased with the rising of knee flexion motion. Likewise, the posterior portion showed more extrusion than the anterior portion on both sides. These measures commonly increased with higher knee flexion.

Clinical significance and management of meniscal extrusion in different knee pathologies: a comprehensive review of the literature and treatment algorithm

The menisci are crescent-shaped, fibrocartilaginous structures that play a crucial role in the load transition and distribution of the contact forces along the tibiofemoral articulation. Meniscal extrusion (ME) is a radiological finding, especially in magnetic resonance imaging (MRI) scans, for which there has been growing interest in recent years. ME, in the coronary plane, is defined as the maximum distance of the most distal end of the meniscus from the border of the tibial plateau, where the tibial eminences are the most prominent, without taking into account the osteophytes. Although there is still controversy in the literature in respect of the optimal cutoff value, a threshold of 3 mm is considered significant. ME has no specific clinical finding or sign and it is encountered in many knee pathologies. It is associated with either rapidly progressive knee osteoarthritis or early onset of knee osteoarthritis and increased morbidity. In this review, we delineate the clinical significance of ME in various knee pathologies, as well as when, why and how it should be managed. To the best of our knowledge, this is the first study to elaborate on these topics.

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.

Repairing Complete Radial Tears of the Lateral Meniscus: Arthroscopic All-Inside Double Vertical Cross-Suture Technique Is Effective and Safe With 2-Year Minimum Follow-Up

PURPOSE

To assess the failure rate and clinical outcomes of the all-inside, double-vertical, cross-suture technique in repairing complete radial tears of the lateral meniscus.

METHOD

We retrospectively reviewed records of patients with this injury on whom the present technique was employed at our institution between 2011 and 2018, with at least 24 months of follow-up. Six months postoperatively, the meniscus healing and extrusion status were evaluated through magnetic resonance imaging. Preoperative and postoperative knee function, measured through IKDC, Lysholm knee, and Tegner activity scale scores, were compared.

RESULTS

In total, 27 patients underwent the procedure. The preoperative mean (standard deviation) IKDC score, Lysholm knee score, and Tegner activity scale scores were 53.4 ± 5.3, 63.2 ± 9.3, and 4 ± .7, respectively. At the last follow-up (≥24 months postoperatively), these scores increased to 92.1 ± 2.6, 90.8 ± 4.2, and 6.1 ± 1.3, respectively (all P < .05). Complete healing of the meniscus was observed in 23 patients, and 4 patients had meniscus retear or nonhealing. The overall retear or nonhealing rate was 14.8%. Healing rates between those with isolated radial tears (87.5%) and those with combined anterior cruciate ligament rupture (84.2%; P = .826) were comparable. No difference was observed in the progression of coronal and sagittal meniscus extrusion (P = .133 and .797, respectively).

CONCLUSION

In patients with complete radial tears of the lateral meniscus, the arthroscopic all-inside double vertical cross-suture repair technique resulted in an 85.2% healing rate, improvements in functional outcomes and activity levels, and no identifiable progression of meniscus extrusion. The all-inside double vertical cross-suture technique is effective and safe for the repair of radial tears of the meniscus.

LEVEL OF EVIDENCE

Level IV, retrospective case series.