Magnetic Resonance Imaging Findings in Symptomatic Patients After Arthroscopic Partial Meniscectomy for Torn Discoid Lateral Meniscus

Long Term Surgical and Radiological Outcome of Discoid Lateral Meniscus: An Updated Systematic Review

Purpose of the study

This study aimed to reach a consensus for ideal surgical treatment of discoid lateral meniscus (DLM) and to evaluate its long term surgical and radiological outcome.

Methods

All authors independently searched for peer reviewed publications with keywords like discoid lateral meniscus, tibial menisci abnormalities, tibial menisci surgery and clinical outcome and their representative Medical Subjects Headings (MeSH) in databases of PubMed, EBSCO, Cochrane Central Register of Controlled Trials, from inception to December 2022. Original articles in English language on discoid lateral meniscus reporting clinical, surgical, or radiological outcomes with five or more years of follow-up were included in this systematic review. Study details and outcome data were analysed according to the age, follow-up period, kind of surgery, DLM type, and alignment.

Results

Our search strategy yielded 654 articles in PubMed, 222 articles in EBSCO and 5 articles in CENTRAL i.e. a total of 881 articles. After detailed assessment and screening, 12 articles were included in the final analysis, which included 444 DLM cases. The mean patient age at surgery ranged from 9.9 to 35.9 years, and the mean follow-up period ranged from 5.2 to 16 years. Partial meniscectomy and meniscoplasty are the recommended treatment because of the concerns of degenerative arthritis development after the total and subtotal meniscectomies. Two studies have documented better results with meniscal allograft transplantation.

Conclusion

Satisfactory clinico-radiological outcome can be obtained after surgical treatment of discoid lateral meniscus with meniscus reshaping and repair of peripheral unstable part. Meniscal allograft transplantation (MAT) is gaining popularity in patients with total meniscectomy with satisfactory long term functional outcome.

Arthroscopic Meniscal Repair and Meniscectomy for Adult Discoid Lateral Meniscus Results in Progression to Valgus Alignment and Lateral Compartment Degeneration Compared With Nonoperative Treatment and Nondiscoid Lateral Meniscus

PURPOSE

To analyze the effect of the arthroscopic meniscal procedure in adult discoid lateral meniscus (DLM) according to the age and meniscal-preserving by making comparisons with the nondiscoid lateral meniscus (N-DLM).

METHODS

From March 2014 to October 2020, a comparative analysis was performed in adults with DLM who underwent arthroscopic meniscal procedures (operative DLM: 134 knees), nonoperative treatment (nonoperative DLM: 56 knees), and adult N-DLM who underwent arthroscopic meniscal procedures (operative N-DLM: 64 knees). These patients were between 20 and 65 years old and completed a minimum follow-up of 2 years. Patients with DLM who underwent arthroscopic procedure were divided into subgroups according to age and extent of the meniscal-preserving. The following parameters were assessed and compared between the groups: (1) coronal limb alignment, (2) osteoarthritis grade, and (3) clinical outcomes and the minimal clinically important difference.

RESULTS

The coronal limb alignment was significantly changed to valgus in the order of operative DLM, N-DLM, and nonoperative DLM (Δ mechanical hip-knee-ankle angle: 3.23 ± 1.85 vs 1.35 ± 1.03° vs -0.57 ± 1.88°; P < .05). Operative DLM showed most prominent osteoarthritic change in the lateral compartment, followed by the N-DLM and nonoperative DLM groups (40.3% vs 17.2% vs 5.3%; P < .05). These changes in operative DLM were more prominent in older adults who underwent meniscal-sacrificing procedures and resulted in less-satisfactory clinical outcomes (all P < .05).

CONCLUSIONS

Arthroscopic surgery for adult DLM resulted in progression to valgus alignment and lateral compartment degeneration compared with nonoperative treatment and arthroscopic surgery of the adult N-DLM. Old ager and having a meniscal-sacrificing procedure showed more rapid radiographic changes and lower clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective comparison study.

Arthroscopic Suture-Saucerization of Discoid Meniscus Allows Volume Conservation but Does Not Fully Restore Coverage

Purpose

The purpose of this study was to quantify the effect of meniscoplasty suture-saucerization on volume and surface coverage of lateral discoid menisci.

Methods

This retrospective study included all consecutive 10 patients treated between 2014 and 2019 who had magnetic resonance imaging before and after surgery and 15 controls. The MITK 3M3 semiautomatic software was used to segment the meniscus and cartilage before and after surgery to measure the percentage of meniscus coverage on the tibial cartilage. Results are compared to control patients without knee pathology matched on sex and age with Student t test.

Results

Discoid meniscus surface and volume before surgery were respectively 597 mm2 (range, 550-887 mm2) and 2,822 mm³ (1,571-3,407 mm³), representing 74.5% (56%-89%) of the tibial cartilage surface. After surgery, it decreased to 422 mm2 (229-569 mm2) and 1,235 mm³ (680-1,738 mm³), leading to 45.7% (22.5%-68.6%) coverage. In the control group, median surface was 457 mm2 (314-641 mm2), volume was 1,321 mm3 (641-2,240 mm3), and tibial coverage was 55% (41%-77%). Altogether, meniscus volume after surgery was similar to normal, while coverage was significantly lower than controls (P = .04).

Conclusions

Meniscoplasty suture-saucerization procedure may allow meniscus sparing and restauration of a similar to normal meniscus volume. Meniscus surface and coverage are diminished compared to controls. Both surface and volume normalization is usually not achievable without decreasing the thickness of the rather thick discoid meniscus.

Clinical Relevance

Both surface and volume normalization is usually not achievable without decreasing the thickness of thick discoid menisci.

Older age and the presence of intrameniscal signs are risk factors for nonsurgical treatment failure of symptomatic intact discoid lateral meniscus

PURPOSE

The treatment for symptomatic intact discoid lateral meniscus (DLM) is controversial and the long-term clinical outcome remains unknown. The purpose of this study was to analyze the overall failure rate of nonsurgical treatment for symptomatic intact DLM and identify the risk factors for nonoperative management failure.

METHODS

Consecutive patients who underwent nonsurgical treatment for symptomatic intact DLM at our hospital from 2014 to 2017 were retrospectively reviewed. Patients were divided into Group A (failure group) and Group B (nonfailure group) based on overall failure criteria: conversion to surgery, progression of a tear on MRI re-examination, or severely abnormal International Knee Documentation Committee (IKDC) scores. Statistical analyses between the two groups were performed for demographic and radiographic characteristics. Multivariate regression analysis was used to determine the risk factors associated with worse outcomes.

RESULTS

One-hundred and four knees in 96 patients were included in this study. After a mean follow-up of 76.9 ± 11.1 months, 25 knees (24.0%) met the overall failure criteria. Multivariate regression analysis demonstrated that age and the presence of intrameniscus signals increased the risk of nonoperative management failure. The clinical criterion of age > 37.5 years combined with the imaging criterion of the presence of intrameniscal signals predicted conservative treatment failure of symptomatic intact DLM with a sensitivity of 0.87 and a specificity of 0.91.

CONCLUSION

Twenty-five (24.0%) knees that underwent nonsurgical treatment met the overall failure criteria after a mean follow-up of 76.9 months. With increased age and the presence of intrameniscal signals, the nonoperative results become worse.

LEVEL OF EVIDENCE

III.

Arthroscopic treatment of the symptomatic discoid lateral meniscus improves the knee function in the long-term: a ten-year follow-up study

PURPOSE

Discoid lateral meniscus (DLM) is a common meniscal anatomic disorder and can cause irreversible knee consequences. The long-term clinical outcomes of DLM management remain unclear. Moreover, several potential factors would influence the long-term functional outcomes. The factors also remain unclear. This study aims to evaluate the long-term clinical outcomes of the arthroscopic management of the DLM and to identify the patients' factors affecting the long-term results.

METHODS

Medical records were retrospectively examined for patients with symptomatic unilateral DLM who underwent arthroscopic procedures between January 2004 and August 2011. The characteristics of DLM, the preoperative and the long-term postoperative visual analog scale (VAS), the International Knee Documentation Committee (IKDC) score, Lysholm, and Yulish scores were evaluated. Data were collected, processed, and analyzed using SAS software version 9.2. Univariate and multivariate analyses were performed to identify the factors influencing the long-term outcomes of the DLM arthroscopy.

RESULTS

A total of 128 patients were included, most of whom were females (68.7%). The median age of the included participants was 24 (16-31) years old. The median duration of symptoms was 23.3 (10, 31) months, and the median follow-up duration was 126.2 (113, 140) months. The functional scores significantly improved postoperatively compared to the preoperative scores; VAS (1.65 ± 1.17 vs. 6.08 ± 1.31), Lysholm (91.39 ± 5.05 vs. 77.51 ± 10.19), and IKDC (84.63 ± 7.69 vs. 67.89 ± 9.56), respectively; p<0.05. Multivariate analysis revealed that gender, the status of self-reported instability, preoperative VAS, Yulish MR cartilage grade, and Lysholm score had a significant correlation with the worsening of the final follow-up IKDC scores.

CONCLUSIONS

Arthroscopic procedure significantly improved the long-term joint function of the DLM patients, as evidenced by the sustained improvement of the VAS, Lysholm, and IKDC scores. These clinical outcomes were greatly influenced by gender, the status of self-reported instability, preoperative Yulish MR cartilage grade, VAS, and Lysholm score.

Mid-term study on the effects of arthroscopic discoid lateral meniscus plasty on patellofemoral joint: An observational study

In the present study, we aimed to investigate the clinical outcomes of arthroscopic discoid lateral meniscus (DLM) plasty and the adaptive changes in the patellofemoral joint after surgery. From September 2010 to March 2012, 25 patients with DLM injuries who underwent arthroscopic meniscus plasty were enrolled in the prospective study. All patients underwent clinical evaluation before the operation and at the last follow-up, and imaging evaluation was performed by upright magnetic resonance imaging before and 1 month after the operation as well as at the last follow-up. Clinical evaluation included Lysholm score, Kujala score, McMurray's sign, patellar mobility, patella grind test, and quadriceps atrophy. Imaging evaluation included bisect offset index, patella tilt angle (PTA), and cartilage damage. Lysholm score, Kujala score, McMurray's sign, and quadriceps atrophy at the last follow-up were significantly improved compared with the preoperative levels (P < .05). At the last follow-up, there were no statistical differences in patella mobility and patella grind test compared with the preoperative levels. In addition, bisect offset index and PTA showed a dynamic trend of rising and then falling over time (P < .05). At 1 month after the operation, bisect offset index and PTA were significantly increased compared with the preoperative levels or the values at the last follow-up (P < .05), while there were no differences between the preoperation and the last follow-up. Cartilage damage became worse with time (P < 0.05), and the 2 were positively correlated (Spearman = 0.368). At the last follow-up, the degree of cartilage damage was significantly increased compared with the preoperative level (P < .017), while there was no significant difference between the 1-month postoperative grade and the preoperational grade or the last follow-up grade. The effect of arthroscopic DLM plasty on the patellofemoral joint was dynamic, with the position of the patella deviating in the early stages and recovering in the mid-term, especially when the knee was in the biomechanical standing position. In addition, the patellofemoral joint cartilage might undergo accelerated degeneration after the operation, while the mid-term effect of the operation was positive, and the patellofemoral joint function was acceptable.

Update on imaging of the discoid meniscus

Discoid menisci represent a range of morphological meniscal variants, most commonly involving the lateral meniscus. Clinical presentation ranges from an asymptomatic incidental finding to snapping, pain, swelling and reduced range of knee movement. Symptomatic presentation of discoid menisci is usually due to meniscal tears and instability resulting from abnormal meniscal morphology and ultrastructure, with absent peri-meniscal ligamentous and meniscocapsular attachments characteristic of the Wrisberg sub-type. This article reviews the current classification systems of discoid menisci, gross morphological characteristics of each sub-type and ultrastructure. Clinical presentation, arthroscopic findings and indirect radiological diagnostic criteria are described, as are the MRI findings of normal and pathological discoid menisci. Current concepts of surgical management and outcomes of the discoid meniscus are also briefly discussed.

The Relationship Between Discoid Meniscus and Articular Cartilage Thickness: A Quantitative Observational Study With MRI

Background:

Several cadaveric imaging studies have demonstrated that the articular cartilage thickness on the tibial plateau varies depending on coverage by native meniscal tissue. These differences are thought to partially contribute to the rates of cartilage degeneration and development of osteoarthritis after meniscectomy. Because there is greater tibial plateau coverage with meniscal tissue in the setting of a discoid meniscus, these findings may also have implications for the long-term health of the knee after saucerization of a torn discoid meniscus.

Purpose:

To evaluate the relationship between lateral compartment articular cartilage thickness and the presence or absence of a discoid meniscus.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Included in the study were 25 patients younger than 40 years of age who had undergone a 1.5-T or 3-T knee magnetic resonance imaging (MRI) between 2010 and 2016 at a single institution and had an intact, lateral discoid meniscus. Only patients with an otherwise asymptomatic lateral compartment were included. The authors then identified 35 age-matched controls with a nondiscoid, intact lateral meniscus who underwent knee MRI at the same institution and during the same period. The articular cartilage thicknesses in 6 zones of the lateral femoral condyle (LFC) and lateral tibial plateau (LTP) were measured for each patient by 2 musculoskeletal radiologists, and the mean thicknesses were compared between the study and control groups.

Results:

The average age at MRI was 22.63 years (range, 8.30-35.90 years) for the discoid group and 20.93 years (range, 8.43-34.99 years) for the nondiscoid group. The nondiscoid group had significantly greater mean articular cartilage thickness in all 6 zones of the LTP (P < .05 for all). When comparing the zones of the LFC, there was no significant difference in the mean thickness in any zone between the 2 groups.

Conclusion:

Patients with discoid menisci had thinner baseline articular cartilage thickness in the LTP compared with those patients without discoid menisci.

Morphological Changes in the Residual Meniscus After Reshaping Surgery for a Discoid Lateral Meniscus

BACKGROUND

Arthroscopic reshaping surgery is the first treatment option for a symptomatic discoid lateral meniscus (DLM) to preserve the peripheral rim. However, the degree of postoperative morphological change in the residual meniscus is unclear.

PURPOSE/HYPOTHESIS

The purpose of this study was to measure the meniscus after reshaping surgery for a DLM, to verify when the morphological change occurred, and to examine the related risk factors. The hypothesis was that the residual meniscal width would decrease throughout the postoperative course.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

We retrospectively reviewed the medical records of patients who underwent reshaping surgery for a symptomatic DLM and had undergone follow-up for ≥2 years. Magnetic resonance imaging (MRI) was routinely performed preoperatively and at 3, 6, 12, and 24 months postoperatively, and the width, height, and extrusion of the residual meniscus were measured. According to the width of the midbody on final MRI scans, we compared the preoperative and postoperative data for the preserved group (≥5 mm) and decreased group (<5 mm). The associated risk factors for a decreased meniscal width (<5 mm) of the midbody were analyzed on final MRI scans.

RESULTS

We included 61 knees of 54 patients in this study. The mean age at the time of surgery was 11.7 years. The intraobserver and interobserver reliabilities of the midbody width were 0.937 and 0.921, respectively. The width of the anterior horn, midbody, and posterior horn decreased significantly from 3 to 24 months after surgery (from 9.1 to 8.6 mm [P < .001], from 7.5 to 6.1 mm [P < .001], and from 9.5 to 8.9 mm [P = .001], respectively). Meniscal extrusion of the midbody did not change significantly (from 1.2 to 1.5 mm; P = .062). Overall, 46 knees (n = 20/32 in the preserved group and n = 26/29 in the decreased group) had longitudinal tears that required meniscal repair. Clinical outcomes did not differ significantly between the 2 groups. Multivariate logistic analysis showed that intrameniscal degeneration (odds ratio, 4.36; P = .023) significantly increased the risk of a decreased meniscal width.

CONCLUSION

The width of the anterior horn, midbody, and posterior horn decreased significantly from 3 to 24 months after surgery. In particular, the average decrease rate of the midbody was 19%. No clinical difference was seen in patients with a decreased width and height or with peripheral extrusion. Increased intrameniscal signals on preoperative MRI scans were associated with an increased risk of a decreased meniscal width. Surgeons should consider this result to determine the amount of resection.

Nationwide Ethnic/Racial Differences in Surgical Treatment of Discoid Meniscus in Children: A PHIS Database Study

BACKGROUND

Discoid meniscus, a congenital meniscus variant, may have greater incidence in Asian populations. No US population-based studies have examined the discoid meniscus ethnic/racial distribution. In pediatric patients undergoing meniscus surgery, it is hypothesized that ethnic/racial variability exists in patients with discoid meniscus and this variability is different than in patients with medial meniscus tears.

METHODS

The Pediatric Health Information System was queried from 48 hospitals to examine patients 18 years of age and younger between 2015 and 2019, using International Classification of Diseases, 10th Revision, Clinical Modification codes. A cohort of patients treated surgically for discoid meniscus was compared with a cohort of patients treated surgically for medial meniscal tear. These 2 populations were compared based on age, sex, ethnicity/race, Current Procedural Terminology code, insurance, urban versus rural, and region of country. Univariate testing and multivariable logistic modeling were used to test for associations.

RESULTS

A discoid meniscus cohort of 399 children (median age, 13.0 y) was compared with a medial meniscus tear cohort of 3157 children (median age, 16.0 y) (P<0.001). Hispanic/Latino children accounted for 36.8% of the discoid lateral meniscus and 22.7% of the medial meniscus populations (P<0.001). Among pediatric patients that had surgery for discoid lateral meniscus or medial meniscus, Hispanic/Latino children had 2.36 times the odds of surgery for discoid meniscus compared with White patients after adjusting for age and insurance (P<0.001). Asian children also had 2.41 times the odds of surgery for discoid meniscus compared with White patients (P=0.017).

CONCLUSIONS

This study shows a significant association of ethnicity/race with discoid versus medial meniscus surgical treatment in children. Among pediatric patients undergoing surgery for discoid meniscus, Hispanic/Latino and Asian patients were a significantly larger percentage of the population than White patients. Hispanic/Latino children made up a greater percentage of the population having surgery for a torn discoid meniscus versus a torn medial mensicus. When evaluating pediatric patients, younger age and Asian or Hispanic/Latino ethnicity should increase attention to the possibility of a discoid meniscus.

LEVEL OF EVIDENCE

Level IV.

Meniscus Repair With Anterior Cord Release for Peripheral Tear Type of Discoid Lateral Meniscus

With improvement in arthroscopic techniques, partial meniscectomy with repair for symptomatic discoid lateral meniscus (DLM) has been the preferred treatment to restore meniscal function. It was reported that DLM exhibited deformation and extrusion shortly after saucerization with repair. Therefore it is desirable to minimize removal of the DLM. The anterior zone of the DLM is often tighter than that of the normal meniscus and anatomic variant. It is considered that the anterior and anterocentral dislocation types in the majority of symptomatic DLM can be related to both peripheral instability and anterior tightness. We present a technique that, first, the inside-out repair technique is applied from the posterior to middle segment of the DLM; next, the tension of the anterior zone during knee flexion-extension is confirmed to determine the released amount of that part; and, finally, all sutures are tied to reproduce the normal meniscus movement. Meniscus repair with anterior cord release without any meniscectomy could resolve peripheral instability of DLM and prevent degeneration of the articular cartilage.

Saucerization and Repair of Discoid Lateral Menisci With Peripheral Rim Instability: Intermediate-term Outcomes in Children and Adolescents

BACKGROUND

Historically, total meniscectomy was recommended as the treatment for a symptomatic discoid meniscus. Improved meniscal repair techniques and inferior long-term outcomes associated with meniscectomy have resulted in a trend toward meniscal preservation, with saucerization and repair of meniscocapsular tears. Reoperation rates after treatment of torn discoid menisci vary, with some series reporting high rates of reinjury and reoperation. The purpose of this study is to describe the intermediate-term outcomes of pediatric patients treated with saucerization and meniscocapsular repair of discoid lateral menisci with peripheral rim instability.

METHODS

A single-institution retrospective review was performed of consecutive patients less than 18 years of age treated with saucerization and repair for a meniscocapsular tear of a discoid lateral meniscus from 2013 to 2017. All patients had a minimum 24-month follow-up. A chart review was performed to describe tear location and repair type. The primary outcomes were revision meniscus surgery and Pedi-International Knee Documentation Committee and Tegner activity scores obtained at the final follow-up.

RESULTS

In total, 32 knees in 30 patients, including 15 males and 15 females with a mean age of 12 years (range, 5 to 17 y), were included. Tear patterns included anterior meniscocapsular (14 knees), posterior meniscocapsular (16 knees), and both anterior and posterior meniscocapsular (2 knees). Arthroscopic saucerization and meniscocapsular repair were performed in all knees. Repair types were outside-in (10 knees), inside-out (8 knees), all-inside (8 knees), and hybrid (6 knees). The mean follow-up was 54 months (range, 30 to 86 mo). Three knees (9%) underwent revision meniscus surgery, including 2 all-inside repairs and 1 partial meniscectomy. At the final follow-up, mean International Knee Documentation Committee score was 96 (range, 82 to 100). A total of 89% of patients reported returning to the same or higher level of activity following surgery.

CONCLUSIONS

Saucerization of discoid lateral menisci with repair of meniscocapsular tears is associated with low rates of revision surgery and good intermediate-term outcomes.

LEVEL OF EVIDENCE

Level IV.

Investigating the Chronology of Meniscus Root Tears: Do Medial Meniscus Posterior Root Tears Cause Extrusion or the Other Way Around?

Background

Meniscus root tears are increasingly being recognized. Meniscal extrusion has previously been associated with medial root tears; however, the relationship between secondary meniscal restraints, such as the meniscotibial (MT) ligament, extrusion, and root tears has yet to be formally evaluated.

Purpose

To better understand the association between MT ligament competence, medial meniscal extrusion, and medial meniscus posterior root tears (MMPRTs) as well as to determine the progression of meniscal extrusion over time.

Study Design

Case series; Level of evidence, 4.

Methods

Serial magnetic resonance imaging (MRI) scans were reviewed for patients who showed evidence of medial meniscal extrusion and MMPRTs on at least 1 of ≥2 available MRI scans. All patients were symptomatic at the time of diagnosis. All MRI scans were analyzed independently by 2 board-certified musculoskeletal radiologists. MT ligament disruption, medial meniscal extrusion, and MMPRTs were recorded for each MRI scan. The time between MRI scans, presence of insufficiency fractures, and Outerbridge classification for the medial femur and tibia were also evaluated.

Results

Overall, 27 knees in 26 patients were included in this study, with a total of 63 MRI scans analyzed (21 knees with 2 MRI scans, 3 with 3 MRI scans, and 3 with 4 MRI scans). All patients demonstrated clear medial meniscal extrusion and MT ligament disruption before the subsequent development of MMPRTs (P < .001). Mean extrusion at the time of initial MRI was 3.3 ± 1.1 mm and increased significantly to 5.5 ± 1.8 mm at the time of first imaging with an identified MMPRT (P < .001). The mean time between initial MRI and the first identification of an MMPRT on later MRI was 1.7 ± 1.6 years.

Conclusion

In a sample of 27 symptomatic knees with serial MRI scans both before and after an MMPRT diagnosis, all patients demonstrated MT ligament disruption and associated meniscal extrusion before the development of subsequent medial meniscus root tears. These findings suggest that MT ligament disruption and medial meniscal extrusion represent early and predisposing events contributing to MMPRTs. Therefore, this provides a possible explanation of why meniscal extrusion is not corrected with medial meniscus root repair.

Discoid lateral meniscus: current concepts

The discoid meniscus is a congenital morphological abnormality encountered far more commonly on the lateral than the medial side. The discoid lateral meniscus (DLM) is more prevalent in Asia with an incidence of 10%-13%, than in the Western world with an incidence of 3%-5%. DLM can be bilateral in more than 80% cases. Due to its abnormal shape and size, the discoid meniscus is prone to tearing and has an impact on gait mechanics. The discoid meniscus has deranged collagen arrangement and vascularity which can have implications for healing after a repair. Patients with a DLM may or may not be symptomatic with mechanical complaints of locking, clicking, snapping or pain. Symptoms often arise due to a tear in the body of the meniscus or a peripheral detachment. Asymptomatic patients usually do not require any treatment, while symptomatic patients who do not have locking are managed conservatively. When a peripheral detachment is present, it must be stabilised while preserving the meniscus rim to allow transmission of hoop stresses. Rehabilitation after surgery is highly individualised and return to sports is possible after more than 4 months in those undergoing a repair. The functional outcomes and onset of radiographic arthritis after saucerisation and repairing a discoid meniscus are better in the long term, compared with a subtotal meniscectomy. However, there is no compelling evidence currently favouring a repair as results deteriorate with increasing follow-up. Poor prognosis is reported in patients undergoing a total meniscectomy, a higher age at presentation and valgus malalignment.

Discoid meniscus: current concepts

Discoid meniscus is the most frequent congenital malformation of the menisci, and primarily affects the lateral meniscus; it is highly prevalent in the Asian population.The anatomic, vascular, and ultrastructural features of the discoid meniscus make it susceptible to complex tears.Discoid meniscus anomalies are described according to their shape; however, there is consensus that peripheral stability of the meniscus should also be defined.Initial workup includes plain X-rays and magnetic resonance imaging, while arthroscopic evaluation confirms shape and stability of the meniscus.Clinical presentation is highly variable, depending on shape, associated hypermobility, and concomitant meniscal tears.Treatment seeks to re-establish typical anatomy using saucerization, tear reparation, and stable fixation of the meniscus. Cite this article: EFORT Open Rev 2020;5:371-379. DOI: 10.1302/2058-5241.5.190023.

The medial open-wegde osteotomy generates progressive intrameniscal integrity changes in the lateral knee compartment: a prospective MR-assessment after valgic osteotomy in the varus gonarthritic knee

PURPOSE

Meniscal changes in the lateral knee compartment after medial-opening high tibial osteotomy (HTO) with valgic overcorrection have not been investigated clinically with magnetic resonance imaging (MRI). The hypothesis of this study was that HTO with valgic overcorrection affects the lateral compartment due to the change in the bearing axis and the shift in the pressure load from the medial to the lateral compartment. This should lead to an accelerated degeneration of the lateral compartment.

METHODS

Twenty-four patients (mean age, 45.7 ± 7.6 years) were prospectively and longitudinally monitored with MRI after medial-opening high tibial osteotomy. The degeneration of the meniscus was assessed at the anterior horn, pars intermedia, and posterior horn using the Stoller classification. The morphological changes were also assessed at the anterior horn, pars intermedia, and posterior horn using the relative vertical and transverse diameters of the examined part of the meniscus, according to the ratio maximal meniscal diameter/maximal tibial width. These parameters were analyzed preoperatively and at follow-up (mean 5.3 ± 1.5 years after surgery).

RESULTS

During the follow-up period, there were no significant morphological changes in either the anterior horn, pars intermedia, or posterior horn. Nor were there any correlations between the morphological parameters, bodyweight, and the follow-up period. Despite these findings, an MRI evaluation showed progressive degeneration in every part of the meniscus according to the Stoller classification, and this was significant at the anterior horn (p < 0.01), pars intermedia (p = 0.021), and posterior horn (p < 0.01).

CONCLUSION

High tibial osteotomy did not lead to morphological changes in the external meniscus over a follow-up period of 5.3 ± 1.5 years. However, progressive degeneration of the meniscus was observed in the imaging data. Further research is required to confirm the observed degeneration and to evaluate the consequences of the observed degeneration.

Management of Long-Term Complications in the Setting of Lateral Meniscal Deficiency After Saucerization of a Discoid Lateral Meniscus in an Adolescent Patient: A Case Report and Review of the Literature

CASE

A 14-year-old adolescent with bilateral discoid menisci who had previously undergone discoid meniscal saucerization presented with pain and mechanical knee symptoms bilaterally. She had a torn left discoid lateral meniscus, a right lateral meniscal deficiency with an associated osteochondral defect, and valgus collapse of the right femur. She underwent successful repair of the left discoid meniscus as well as a femoral osteotomy, a meniscal transplant, and an osteochondral allograft transplantation in the right knee.

CONCLUSION

New treatment paradigms following initial interventions for discoid menisci are discussed. Patients may benefit from longer follow-up after discoid meniscal surgery, and providers should consider joint-preserving techniques early in the setting of meniscal deficiency.

Clinical Outcomes of Meniscal Allograft Transplantation With or Without Other Procedures: A Systematic Review and Meta-analysis

BACKGROUND

While additional procedures correcting accompanying pathological conditions can improve the clinical outcomes of meniscal allograft transplantation (MAT), whether those outcomes are comparable or poorer than those of isolated MAT has yet to be clarified.

PURPOSE

To evaluate whether there is a difference in clinical outcomes between isolated MAT and MAT combined with other procedures (combined MAT).

STUDY DESIGN

Meta-analysis and systematic review.

METHODS

For the comparison of clinical outcomes between isolated MAT and combined MAT, the authors searched MEDLINE, Embase, and the Cochrane Library. Studies that separately reported the clinical outcomes of isolated MAT and combined MAT were included. Clinical outcomes were evaluated in terms of patient-reported outcomes (PROs) and complication, reoperation, survivorship, and failure rates. We conducted a meta-analysis of the PROs that were used in more than 3 studies.

RESULTS

A total of 24 studies were included in this study. In the meta-analysis, no significant differences in Lysholm scores (95% CI, -5.92 to 1.55; P = .25), Tegner activity scores (95% CI, -0.54 to 0.22; P = .41), International Knee Documentation Committee subjective scores (95% CI, -5.67 to 3.37; P = .62), and visual analog scale scores (95% CI, -0.15 to 0.94; P = .16) were observed between isolated MAT and combined MAT. For PROs that were not included in the meta-analysis, most studies reported no significant difference between the 2 groups. As for the survivorship and failure rates, studies showed varying outcomes. Four studies reported that additional procedures did not affect MAT failure or survivorship. However, 3 studies reported that ligament surgery, realignment osteotomy, and osteochondral autograft transfer were risk factors of failure. One study reported that the medial MAT group in which high tibial osteotomy was performed showed a higher survival rate than the isolated medial MAT group.

CONCLUSION

Overall, there seems to be no significant difference between the postoperative PROs in terms of isolated MAT and combined MAT. However, more data are required to verify the effects of osteotomy and cartilage procedures on the clinical outcomes of MAT. We could not draw conclusions about the differences in complication, reoperation, survivorship, and failure rates between the 2 groups because we did not obtain sufficient data.

Discoid lateral meniscus can be overlooked by magnetic resonance imaging in patients with meniscal tears

PURPOSE

MRI evaluation of torn lateral meniscus was compared with arthroscopy. This study calculates the sensitivity, specificity, and accuracy of MRI in determining the presence or absence of discoid lateral meniscus (DLM) for different tear types.

METHODS

MR imaging of 156 knees with arthroscopically confirmed lateral meniscus tears was analysed. There were 78 knees (70 patients) in non-DLM group and 78 knees (74 patients) in DLM group on arthroscopy as the reference standard. The presence of DLM on MRI was determined by an orthopaedic surgeon and a radiologist, who were blinded to the arthroscopic findings. The presence of discoid meniscus on MRI was determined by coronal and sagittal measurements, considering the tear pattern of lateral meniscus. The tear pattern was categorized into six types based on arthroscopic findings: horizontal, longitudinal, radial, combined radial, degenerative, and complex tear. The sensitivity, specificity, and accuracy of MRI were calculated for each type of lateral meniscus tear. In addition, we analysed the reason for non-detection of discoid meniscus on preoperative MRI.

RESULT

The sensitivity for determining the presence of discoid meniscus was 58% for radial tear, 57% for combined radial tear, and 65% for longitudinal tear, whereas the specificity was 100% for all tear groups. In the presence of radial or longitudinal tear, the accuracy of MRI was significantly lower than having no radial and longitudinal tear (p < 0.001). The presence of discoid meniscus was not recognized on MRI because of large radial tear (12 knees), deformed bucket-handle tear (6 knees), and inverted flap tear (3 knees).

CONCLUSIONS

MRI was not successful in determining the presence or absence of DLM in radial tear, combined radial tear, and longitudinal tear. When there are large radial tear, deformed bucket-handle tear, and inverted flap tear in lateral meniscus, it is recommended to consider the possibility of DLM. This information can help to make accurate diagnosis of DLM, which allows appropriate surgical planning and facilitates patient's information on poor prognosis of DLM.

LEVEL OF EVIDENCE

Level I.

Systematic Review of the Long-term Surgical Outcomes of Discoid Lateral Meniscus

PURPOSE

To evaluate the surgical treatment of the discoid lateral meniscus (DLM) with long-term follow-up and to search which factors are related to good clinical or radiological outcomes.

METHODS

Search was performed using a MEDLINE, EMBASE, and Cochrane database, and each of the selected studies was evaluated for methodological quality using a risk of bias (ROB) covering 7 criteria. Clinical and radiological outcomes with more than 5 years of follow-up were evaluated after surgical treatment of DLM. They were analyzed according to the age, follow-up period, kind of surgery, DLM type, and alignment.

RESULTS

Eleven articles (422 DLM cases) were included in the final analysis. Among 7 criteria, 3 criteria showed little ROB in all studies. However, 4 criteria showed some ROB ("Yes" in 63.6% to 81.8%). The minimal follow-up period was 5.5 years (weighted mean follow-up: 9.1 years). Surgical procedures were performed with open or arthroscopic partial central meniscectomy, subtotal meniscectomy, total meniscectomy, or partial meniscectomy with repair. The majority of the studies showed good clinical results. Mild joint space narrowing was reported in the lateral compartment, but none of the knees demonstrated moderate or advanced degenerative changes. Increased age at surgery, longer follow-up period, and subtotal or total meniscectomy could be related to degenerative change. The majority of the complications was osteochondritis dissecans at the lateral femoral condyle (13 cases) and reoperation was performed by osteochondritis dissecans (4 cases), recurrent swelling (2 cases), residual symptom (1 case), stiffness (1 case), and popliteal stenosis (1 case).

CONCLUSIONS

Good clinical results were obtained with surgical treatment of symptomatic DLM. The progression of degenerative change was minimal and none of the knees demonstrated moderate or advanced degenerative changes. Increased age at surgery, longer follow-up period, and subtotal or total meniscectomy were possible risk factors for degenerative changes.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.