Discoid lateral meniscus: a simple horizontal tear was associated with less articular cartilage degeneration compared to other types of tear

Adults Have a Higher Incidence of Discoid Lateral Meniscus Tears Than Children-Adults Tend to Present With Complex Tears, While Horizontal Tear Patterns are Frequently Encountered in Children: A Systematic Review

PURPOSE

To systematically review the available literature in patients with discoid lateral meniscus (DLM) with the goal of elucidating the rates and types of meniscal tears, clinical symptoms, treatment strategies, and postoperative clinical, and radiographic outcomes in adult patients compared with a pediatric population.

METHODS

A literature search was performed using the PubMed, Embase, and Scopus databases from database inception to October 2023 according to the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Level of evidence I through IV human clinical studies evaluating rate and type of meniscal tears, clinical symptoms, patient-reported outcome measures, and postoperative radiographical assessments in patients with DLM were included. Comparisons were made by age below and above 16 years. Study quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria.

RESULTS

Thirteen studies comprising of 1772 adult patients (>16 years old) with DLM (n=1856 knees) and eight studies conducted in 304 pediatric patients (≤16 years old, n=353 knees) were include. The reported mean age ranged from 22.4 to 45 years (mean follow-up, 24 to 157.5 months) in the adult group and from 5 to 12.9 years (mean follow-up,37 to 234 months) in the pediatric DLM group. The majority of adult (n=553; 96.5%) and pediatric (n=163; 71.8%) patients had tears of the DLM. Complete DLM was the predominant type of DLM in both study groups (range in adults, 49.6 to 88%; range in pediatric, 19 to 100%) with complex (46.1%; range, 5.3-100%) and horizontal tears (18.2%; range, 20-37.5) being the most frequently described tear patterns in the adult and pediatric DLM groups, respectively. Pain was the predominant reported symptom in both study groups (range in adults, 12.1 to 99.3%; range in pediatrics, 32.4 to 100%). Partial meniscectomy was the most frequently reported treatment option conducted in 334 adult (39.5%; range, 24.2-100%) and 66 pediatric knees (63.5%; range, 15-100%).. Overall, improved postoperative clinical outcomes were reported in both study groups; however, radiographic progression of degenerative changes after subtotal meniscectomy was noted.

CONCLUSIONS

More adult patients with DLM present with tears in the literature compared with the pediatric population. Complex and horizontal tear patterns are the most frequently reported tears in adult and pediatric patients, respectively. . Pain is the most relevant symptom in both study groups. There was generally significant improvement in postoperative clinical outcome scores; partial meniscectomy however remains the most frequently reported treatment option and is associated with fewer degenerative changes than in subtotal meniscectomy. .

STUDY DESIGN

Level IV, Systematic review of Level I-IV studies.

Biomechanical effects of the medial meniscus horizontal tear and the resection strategy on the rabbit knee joint under resting state: finite element analysis

The biomechanical changes following meniscal tears and surgery could lead to or accelerate the occurrence of osteoarthritis. The aim of this study was to investigate the biomechanical effects of horizontal meniscal tears and different resection strategies on a rabbit knee joint by finite element analysis and to provide reference for animal experiments and clinical research. Magnetic resonance images of a male rabbit knee joint were used to establish a finite element model with intact menisci under resting state. A medial meniscal horizontal tear was set involving 2/3 width of a meniscus. Seven models were finally established, including intact medial meniscus (IMM), horizontal tear of the medial meniscus (HTMM), superior leaf partial meniscectomy (SLPM), inferior leaf partial meniscectomy (ILPM), double-leaf partial meniscectomy (DLPM), subtotal meniscectomy (STM), and total meniscectomy (TTM). The axial load transmitted from femoral cartilage to menisci and tibial cartilage, the maximum von Mises stress and the maximum contact pressure on the menisci and cartilages, the contact area between cartilage to menisci and cartilage to cartilage, and absolute value of the meniscal displacement were analyzed and evaluated. The results showed that the HTMM had little effect on the medial tibial cartilage. After the HTMM, the axial load, maximum von Mises stress and maximum contact pressure on the medial tibial cartilage increased 1.6%, 1.2%, and 1.4%, compared with the IMM. Among different meniscectomy strategies, the axial load and the maximum von Mises stress on the medial menisci varied greatly. After the HTMM, SLPM, ILPM, DLPM, and STM, the axial load on medial menisci decreased 11.4%, 42.2%, 35.4% 48.7%, and 97.0%, respectively; the maximum von Mises stress on medial menisci increased 53.9%, 62.6%, 156.5%, and 65.5%, respectively, and the STM decreased 57.8%, compared to IMM. The radial displacement of the middle body of the medial meniscal was larger than any other part in all the models. The HTMM led to few biomechanical changes in the rabbit knee joint. The SLPM showed minimal effect on joint stress among all resection strategies. It is recommended to preserve the posterior root and the remaining peripheral edge of the meniscus during surgery for an HTMM.

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.

Reliability of a New Arthroscopic Discoid Lateral Meniscus Classification System: A Multicenter Video Analysis

BACKGROUND

The discoid lateral meniscus (DLM) is one of the most common congenital anomalies of the knee. The pathomorphology of DLM varies. Current classification systems are inadequate to describe the spectrum of abnormality.

PURPOSE

A study group of pediatric orthopaedic surgeons from 20 academic North American institutions developed and tested the reliability of a new DLM classification system.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

After reviewing existing classifications, we developed a comprehensive DLM classification system. Four DLM features were evaluated: meniscal width, meniscal height, peripheral stability, and meniscal tear. Stepwise arthroscopic examination using anteromedial and anterolateral viewing portals was established for evaluating these features. Three senior authors who were not observers selected 50 of 119 submitted videos with the best clarity and stepwise examination for reading. Five observers performed assessments using the new classification system to assess interobserver reliability, and a second reading was performed by 3 of the 5 observers to assess intraobserver reliability using the Fleiss κ coefficient (fair, 0.21-0.40; moderate, 0.41-0.60; substantial, 0.61-0.80; excellent, 0.81-1.00).

RESULTS

Interobserver reliability was substantial for most rating factors: meniscal width, meniscal height, peripheral stability, tear presence, and tear type. Interobserver reliability was moderate for tear location. Intraobserver reliability was substantial for meniscal width and meniscal height and excellent for peripheral stability. Intraobserver agreement was moderate for tear presence, type, and location.

CONCLUSION

This new arthroscopic DLM classification system demonstrated moderate to substantial agreement in most diagnostic categories analyzed.

Discoid Lateral Meniscus Saucerization and Treatment of Intrasubstance Degeneration Through an Accessory Medial Portal Using a Small Arthroscope

Discoid lateral meniscus (DLM) is a rare meniscal variant characterized by an increased amount of meniscal tissue that resembles the shape of a disc as opposed to the typical crescent shape of the lateral meniscus. Surgical intervention is recommended for symptomatic DLM with persistent pain, mechanical symptoms, or motion impairment. The technique described is a reliable and reproducible method to identify and treat intrasubstance degeneration (ID) in the setting of DLM. A small arthroscope is used that allows more room for a meniscal repair device, as well as improved visualization and access of the lateral compartment. An accessory medial portal is used that allows perpendicular access to the anterior half of the body, as well as the posterior aspect of the anterior horn for repair. Successful surgery with this technique preserves meniscus and produces a strong reliable all-meniscal based repair of ID that allows early weight bearing and range of motion postoperatively.

A predictive model with radiographic signs can be a useful supplementary diagnostic tool for complete discoid lateral meniscus in adults

PURPOSE

To investigate the diagnostic accuracy of radiographic signs for complete discoid lateral meniscus and whether a predictive model combining the radiographic signs can improve its diagnostic accuracy in adults.

METHODS

A total of adult 119 knees with complete discoid lateral meniscus confirmed by arthroscopy and 119 age- and sex-matched knees with normal meniscus were included. The radiographic signs of lateral joint space, fibular head height, lateral tibial spine height, lateral tibial plateau obliquity, lateral femoral condyle squaring, lateral tibial plateau cupping, lateral femoral condyle notching, and the condylar cut-off sign were evaluated. The receiver-operating characteristic (ROC) curves and area under the curve (AUC) were evaluated for best accuracy. A prediction model was developed by multivariable regression with generalized estimating models, and was validated using data from 111 knees of children with complete discoid lateral meniscus and 111 normal controls.

RESULTS

The fibular head height, lateral joint space, lateral tibial plateau obliquity, and the condylar cut-off sign were significantly different between the complete discoid lateral meniscus and the normal groups (p < 0.05). Among the four radiographic signs, the fibular head height showed the highest accuracy with 78.9% sensitivity and 57.3% specificity. The prediction models developed by logistic regression showed significantly improved accuracy for complete discoid lateral meniscus compared to the fibular head height (sensitivity: 69.8%, specificity: 82.9%, p = 0.001). For validation, the AUC of children seemed to be larger than that of adults, which indicated that the prediction models could be applied for children to detect complete discoid lateral meniscus.

CONCLUSION

Among several radiographic signs, the fibular head height can be used as a screening tool for complete discoid lateral meniscus. The prediction models combined with lateral joint space, fibular head height, lateral tibial plateau obliquity, and/or the condylar cut-off sign yielded a much higher diagnostic value than each radiographic sign. Therefore, fibular head height and prediction models combined with radiographic signs can provide improved diagnostic value for complete discoid lateral meniscus.

LEVEL OF EVIDENCE

III.

Natural history of new horizontal meniscal tears in individuals at risk for and with mild to moderate osteoarthritis: data from osteoarthritis initiative

OBJECTIVES

To study the natural history of new horizontal meniscal tears and their association with progression of cartilage degeneration in individuals at risk for or with mild to moderate knee osteoarthritis over 4 years.

METHODS

Individuals who developed a new meniscal tear in the right knee over 2 years were selected from the Osteoarthritis Initiative 3T MRI studies. Knee structural changes were analyzed at the time of tear appearance (baseline), and after 4 years using a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS). Meniscal tears were classified as either horizontal tears or non-horizontal tears. Individuals without a meniscal tear were 1:3 frequency matched according to BMI, gender, race, and age and served as the control group. Linear regression analysis was used to compare cross-sectional and longitudinal changes in cartilage WORMS scores.

RESULTS

Forty-one subjects developed horizontal tears, including one indiviudal who developed a tear in both menisci, and 34 developed non-horizonal tears. We found that (29/41 (70.7%)) of horizontal and (20/34 (58.8%)) of non-horizonatal tears were stable during follow-up (p = 0.281). Although knees with an incident tear had higher than controls WORMS MAX total knee scores at baseline (coef. = 0.47, p = 0.044, 95% CI = 0.01 to 0.93), there were no significant differences between the horizontal subgroup and knees without tears in overall cartilage scores at baseline and in progression over 4 years of follow-up.

CONCLUSIONS

New horizontal meniscal tears tended to be stable over 4 years and presented no significant differences in progression of cartilage degeneration when compared with knees without tears.

KEY POINTS

• Most of horizonal meniscal tears were stable over 4 years. • There were no statistically significant differences in overall progression of cartilage degenerative changes between knees with horizonal meniscal tears and control knees without tears • Horizontal tears most often occurred at the posterior horn of the medial meniscus and at the body of the lateral meniscus.

Discoid lateral meniscus: importance, diagnosis, and treatment

Discoid lateral meniscus (DLM) is a common anatomic variant in the knee typically presented in young populations, with a greater incidence in the Asian population than in other populations. As DLM is a congenital anomaly, the ultrastructural features and morphology differ from those of the normal meniscus, potentially leading to meniscal tears. Snapping and pain are common symptoms, with occasional limitations of extension, in patients with DLM. Examination of the contralateral knee is necessary as DLM affects both knees. While simple radiographs may provide indirect signs of a DLM, magnetic resonance imaging (MRI) is essential for diagnosis and treatment planning. Although DLM was traditionally classified into three categories, namely, complete, incomplete, and Wrisberg DLM, a recent MRI classification provides useful information for surgical planning because the MRI classification was based on the peripheral detachment in patients with DLM, as follows: no shift, anterocentral shift, posterocentral shift, and central shift. Asymptomatic patients require close follow-up without surgical treatment, while patients with symptoms often require surgery. Total or subtotal meniscectomy, which has been traditionally performed, leads to an increased risk of degenerative arthritis; thus, partial meniscectomy is currently considered the treatment of choice for DLM. In addition to partial meniscectomy, meniscal repair of peripheral detachment is recommended for stabilization in patients with DLM to preserve the function of the meniscus. Previous studies have reported that partial meniscectomy with or without meniscal repair is effective and shows superior clinical and radiological outcomes to those of total or subtotal meniscectomy during the short- to long-term follow-up. Our preferred principle for DLM treatment is reduction, followed by reshaping with reference to the midbody of the medial meniscus and repair as firm as possible.

Knee orthopedic problems in newborns and infancy: a review

PURPOSE OF REVIEW

We present the reader with insight on the most common disorders of the knee in newborns and infants. Knee issues in this population may confuse the first contact physicians due to certain peculiarities of the immature immune system, small size and underdevelopment of joint anatomy. Data presented here are recent and significant, and something to bear in mind when caring for children of this age.

RECENT FINDINGS

With the advent of new diagnostic methods, a shift in the causative agent of pediatric knee infections has been noted. Minimally invasive methods such as arthrocentesis and arthroscopy are successfully employed in treatment of knee problems in newborns and infants. A trial of conservative therapy in congenital patellar instability can give good results, and obviate the need for surgery in some cases. Various syndromes that affect the knee have specific characteristics that need to be recognized early to avoid problems in the future.

SUMMARY

Although rare, knee problems in infants can and do occur. Their cause varies significantly and good outcomes require a multidisciplinary approach. Early diagnosis, referral and initiation of treatment protocols can significantly influence the fate of the joint and with it the patients' functional status for life.