Discoid meniscus:Treatment considerations and updates

A discoid meniscus is a morphological abnormality wherein the meniscus loses its normal‘C’shape.Although most patients are asymptomatic,patients might still present with symptoms such as locking,pain,swelling,or giving way.Magnetic resonance imaging is usually needed for confirmation of diagnosis.Based on a constellation of factors,including clinical and radiological,different approaches are chosen for the management of discoid meniscus.The purpose of this review is to outline the treatment of discoid meniscus,starting from conservative approach,to the different surgical options for this condition.The PubMed and Google Scholar databases were used for this review.Studies discussing the treatment of discoid meniscus from 2018 to 2023 were searched.Initially there were 369 studies retrieved,and after removal of studies using the exclusion criteria,26 studies were included in this review.Factors such as stability,presence of tear,and morphology can help with surgical planning.Many approaches have been used to treat discoid meniscus,where the choice is tailored for each patient individually.Postoperatively,factors that may positively impact patient outcomes include male sex,body mass index<18.5,age at symptom onset<25 years,and duration of symptoms<24 months.The conventional approach is partial meniscectomy with or without repair;however,recently,there has been an increased emphasis on discoid-preserving techniques such as meniscoplasty,meniscopexy,and meniscal allograft transplantation.

Congenital absence of the lateral meniscus:A case report

BACKGROUND Congenital absence of the menisci is a rare anatomical variation characterized by the absence or underdevelopment of one or both menisci in the knee joint.The menisci are crucial in load distribution,joint stability,and shock absorption.Understanding the clinical presentation,diagnosis,and management of this condition is important for optimal patient care.CASE SUMMARY A 27-year-old male with a long-standing history of knee pain underwent diagnostic arthroscopy,revealing a congenital absence of the meniscus.The patient's clinical findings,imaging results,surgical procedures,and pertinent images are detailed.This case presents a unique aspect with the congenital absence of the meniscus,contributing valuable insights to the literature on rare anatomical anomalies.CONCLUSION This case of congenital absence of the menisci highlights the diagnostic challenges posed by rare anomalies.The diagnostic arthroscopy played a crucial role in identifying the absence of the meniscus and providing an explanation for the patient's persistent knee pain.The case underscores the importance of individualized treatment approaches,including physical therapy,for optimal management of rare meniscal anomalies.Further research is warranted to explore effective management strategies for the aforementioned cases and to expand our knowledge of these rare conditions.

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 readerfriendly 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.

The Prevalence Type of the Meniscus Tear in Patients with Anterior Cruciate Ligament (ACL) Injury, in Abu Arish General Hospital, Jazan, KSA

Background: The anterior cruciate ligament (ACL) is the main structure that prevents the forward movement of the tibia about the femur Meniscus tear which is a common finding in patients with anterior cruciate ligament (ACL) injury. Aim: To investigate the prevalence of types of meniscus tears in patients with Anterior Cruciate Ligament (ACL) Injury. Methods: A retrospective study was conducted among inpatients. Clinical evaluation included side-to-side difference in anterior tibial translation (ATT) as measured by a KT-1000 arthrometer (MEDmetric Corp) and a grade of pivot-shift test at final follow-up in all patients. Subsequent meniscal tear was defined by symptoms of joint line pain and/or locking or joint effusion requiring surgical treatment. Results: Most of patients were males (92.6%). The patients were categorized into 5 groups according to age with a mean of age 32.8 ± 10.6. The most common causes of ACL injury were falling down (43.2%), trauma (38.1%) or knee torsion (18.8%). Medial meniscal tear was found in 92 knees (55.7%), while lateral meniscal tear was found in 19 knees (10.8%) and the most common type was the longitudinal tear that was found in 31 knees (17.6%). Similarly, 66.7% of the meniscal flap tears and half of the meniscal bucket-handle tears were significantly associated with loose body (P Conclusion: The present study demonstrated that meniscus tears are more common in individuals with chronic ACL rupture. The main factors contributing to ACL injury were classified as falls, trauma, and knee torsion. Gender was identified as a critical determinant in the etiology of ACL injury. The occurrence of a ramp lesion was associated longitudinal meniscal tears, whereas chodoral injury was associated with the majority of meniscal flap tears and meniscal bucket-handle tears.

Recent advances in meniscus-on-demand three-dimensional micro-and nano-printing for electronics and photonics

The continual demand for modern optoelectronics with a high integration degree and customized functions has increased requirements for nanofabrication methods with high resolution,freeform,and mask-free.Meniscus-on-demand three-dimensional(3D)printing is a high-resolution additive manufacturing technique that exploits the ink meniscus formed on a printer nozzle and is suitable for the fabrication of micro/nanoscale 3D architectures.This method can be used for solution-processed 3D patterning of materials at a resolution of up to100 nm,which provides an excellent platform for fundamental scientific studies and various practical applications.This review presents recent advances in meniscus-on-demand 3D printing,together with historical perspectives and theoretical background on meniscus formation and stability.Moreover,this review highlights the capabilities of meniscus-on-demand 3D printing in terms of printable materials and potential areas of application,such as electronics and photonics.

Dynamic tear meniscus parameters in complete blinking:insights into dry eye assessment

AIM:To investigate the relationship between dynamic tear meniscus parameters and dry eye using an automated tear meniscus segmentation method.METHODS:The analysis of tear meniscus videos captured within 5s after a complete blink includes data from 38 participates.By processing video data,several key parameters including the average height of the tear meniscus at different lengths,the curvature of the tear meniscus’s upper boundary,and the total area of the tear meniscus in each frame were calculated.The effective values of these dynamic parameters were then linearly fitted to explore the relationship between their changing trends and dry eye disease.RESULTS:In 94.74%of the samples,the average height of central tear meniscus increased over time.Moreover,97.37%of the samples exhibited an increase in the overall tear meniscus height(TMH)and area from the nasal to temporal side.Notably,the central TMH increased at a faster rate compared to the nasal side with the temporal side showing the slowest ascent.Statistical analysis indicates that the upper boundary curvature of the whole tear meniscus as well as the tear meniscus of the nasal side(2,3,and 4 mm)aid in identifying the presence of dry eye and assessing its severity.CONCLUSION:This study contributes to the understanding of tear meniscus dynamics as potential markers for dry eye,utilizing an automated and non-invasive approach that has implications for clinical assessment.

An Improved Transosseous Pullout Suture Technique for Arthroscopic Repair of a Meniscus Root Tear

Objective:This study aimed to explore the clinical efficiency of an improved transosseous pullout suture technique for arthroscopic repair of a meniscus root tear.Methods:From January 2017 to January 2021,53 patients with posterior meniscus root tears combined with anterior cruciate ligament(ACL)and/or posterior cruciate ligament(PCL)tears were collected.Totally,in 29 patients(group A),the 2.0 mm modified pullout tunnel method was used to suture the posterior meniscus root,while 24 patients(group B)were treated with the traditional 4.5 mm pullout tunnel method.In group A,20 patients had lateral meniscus posterior root(LMPR)combined with ACL tears,5 patients had LMPR combined with ACL and PCL tears,and 4 patients had medial meniscus posterior root(MMPR)combined with ACL tears.In group B,19 patients had LMPR combined with ACL tears,3 patients had LMPR combined with ACL and PCL tears,and 2 patients had MMPR combined with ACL tears.The improvement of the Lysholm and VAS scores and the incidence of complications in group A and group B before the operation,1 month and 3 months after the operation,and after the final follow-up were compared.Results:Preoperative Lysholm score was 26.0±5.6 in group A and 26.7±5.8 in group B(P>0.05).One-month postoperative Lysholm score was 66.5±5.7 in group A and 54.3±2.4 in group B(P<0.001).Three-month postoperative Lysholm score was 81.1±7.2 in group A and 73.2±9.7 in group B(P<0.05).Lysholm scores after the final follow-up was 90.3±5.6 in group A and 90.0±5.0 in group B(P>0.05).Preoperative VAS score was 6.3±1.4 in group A and 6.3±1.2 in group B(P>0.05).One-month postoperative VAS score was 1.8±0.7 in group A and 2.4±0.9 in group B(P<0.05).Three-month postoperative VAS score was 0.7±0.6 in group A and 0.8±0.6 in group B(P>0.05).VAS score after the final follow-up was 0.2±0.4 in group A and 0.3±0.5 in group B(P>0.05).Conclusion:The improved transosseous pullout suture technique using a smaller 2.0 mm bone tunnel can virtually eliminate the risk of conflict with other bone tunnels and facilitate the management of bone tunnels in multiple ligament injuries,while also diminishing suture abrasion caused by the windshield wiper effect.The technique achieves good clinical efficacy.

基于二维Meniscus透镜的准光功率合成器(英文)

为了实现大功率容量和高效率的空间功率合成,将基于波导腔体的二维Meniscus透镜用于毫米波功率合成器的设计.对透镜中传输的主模(TE10波)的散射效应进行了分析,并且设计了匹配层减小透镜结构带来的反射.在30GHz频率上利用Rexolite介质的Meniscus透镜设计出了10路功率合成器,对不同结构的功率合成器和不同参数的透镜进行了研究,得到了最终的优化结果.CST-MMW的仿真结果表明该功率合成器在30GHz合成效率可以达到92.6%,并且其80%以上效率工作带宽可以覆盖整个Ka波段.

Meniscus Behavior in Electromagnetic Soft-Contact Continuous Casting Round Billet Mold

Using molten Pb-Sn-Bi alloy, the meniscus shape under high frequency magnetic field of φ100 mm round billet caster was investigated. The effect of some parameters on meniscus shape was studied. The results show that for a mold with 12 segments, the meniscus shape is relatively stable. With increasing power input, the menis- cus height increases with intensification of fluctuation. For the given caster, the reasonable power input is about 70 kW. The coil should be near to the top of mold and/or the initial meniscus should be near to the center of the coil. The lower the frequency, the higher is the meniscus height. With increasing frequency, the free surface is more flattened and meniscus becomes more stable. In practice, the power input should be increased simultaneously with frequency. The optimal frequency is about 20 kHz.

An Elastic-plastic Adhesion Model for Contacting Fractal Rough Surface and Perfectly Wetted Plane with Meniscus

The strong stiction of adjacent surfaces with meniscus is a major design concern in the devices with a micro-sized interface. Today, more and more research works are devoted to understand the adhesion mechanism. This paper concerns the elastic-plastic adhesion of a fractal rough surface contacting with a perfectly wetted rigid plane. The topography of rough surface is modeled with a two-variable Weierstrass-Mandelbrot fractal function. The Laplace pressure is dealt with the Dugdale approximation. Then the adhesion model of the plastically deformed asperities with meniscus can be established with the fractal microcontact model. According to the plastic flow criterion, the elastic-plastic adhesion model of the contacting rough surfaces with meniscus can be solved by combining the Maugis-Dugdale （MD） model and its extension with the Morrow method. The necessity for considering the asperities＇ plastic deformation has been validated by comparing the simulation result of the presented model with that of the elastic adhesion model. The stiction mechanism of rough surfaces with meniscus is also discussed.

Degenerative meniscus: Pathogenesis, diagnosis, and treatment options

The symptomatic degenerative meniscus continues to be a source of discomfort for a significant number of patients. With vascular penetration of less than onethird of the adult meniscus, healing potential in the setting of chronic degeneration remains low. Continued hoop and shear stresses upon the degenerative meniscus results in gross failure, often in the form of complex tears in the posterior horn and midbody. Patient history and physical examination are critical to determine the true source of pain, particularly with the significant incidence of simultaneous articular pathology. Joint line tenderness, a positive Mc Murray test, and mechanical catching or locking can be highly suggestive of a meniscal source of knee pain and dysfunction. Radiographs and magnetic resonance imaging are frequently utilized to examine for osteoarthritis and to verify the presence of meniscal tears, in addition to ruling out other sources of pain. Non-operative therapy focused on nonsteroidal anti-inflammatory drugs and physical therapy may be able to provide pain relief as well as improve mechanical function of the knee joint. For patients re-fractory to conservative therapy, arthroscopic partial meniscectomy can provide short-term gains regarding pain relief, especially when combined with an effective, regular physiotherapy program. Patients with clear mechanical symptoms and meniscal pathology may benefit from arthroscopic partial meniscectomy, but surgery is not a guaranteed success, especially with concomitant articular pathology. Ultimately, the long-term outcomes of either treatment arm provide similar results for most patients. Further study is needed regarding the short and long-term outcomes regarding conservative and surgical therapy, with a particular focus on the economic impact of treatment as well.

Lipid layer thickness and tear meniscus height measurements for the differential diagnosis of evaporative dry eye subtypes

AIM： To explore a new diagnostic index for differentiating the evaporative dry eye（EDE） subtypes by analysis of their respective clinical characteristics. METHODS： A cross-sectional study of 139 patients（139 eyes） with EDE who were enrolled and classified as obstructive meibomian gland dysfunction（MGD）（n=81） and non-obstructive MGD（n=58） EDE. All patients completed a Standard Patient Evaluation of Eye Dryness（SPEED） questionnaire and were evaluated for average lipid layer thickness（LLT）, tear meniscus height measurements（TMH）, tear break-up time（TBUT）, ocular surface staining score, Schirmer I test（SIT）, lid margin abnormalities, and meibomian gland function and morphology. RESULTS： Age, average LLT, TMH, scores of lid margin abnormalities, meibum quality, meibomian gland loss（MGL）（all P≤0.001）, and TBUT（P=0.03） were all significantly different between obstructive MGD EDE patients and nonobstructive MGD EDE patients. Average LLT in obstructive MGD EDE was correlated with meibomian expressibility（r=-0.541, P≤0.001）, lid margin abnormalities were marginally not significant（r=0.197, P=0.077）, and TMH was correlated with MGL（total MGL： r=0.552, P≤0.001; upper MGL： r=0.438, P≤0.001; lower MGL： r=0.407, P≤0.001）. Average LLT in non-obstructive MGD EDE, was correlated with meibomian expressibility and Oxford staining（r=-0.396, P=0.002; r=-0.461, P≤0.001）. The efficiency of combining average LLT and TMH was optimal, with a sensitivity of 80.2% and a specificity of 74.1%. Obstructive MGD EDE patients had an average LLT≥69 nm and TMH≥0.25 mm, while non-obstructive MGD EDE patients had an average LLT〈69 nm and TMH〈0.25 mm.CONCLUSION： Obstructive MGD EDE and nonobstructive MGD EDE have significantly different clinical characteristics. Combining average LLT and TMH measurements enhanced their reliability for differentiating these two subtypes and provided guidance for offering more precise treatments for EDE subtypes.

Indirect printing of hierarchical patient-specific scaffolds for meniscus tissue engineering

The complex meniscus tissue plays a critical role in the knee. The high susceptibility to injury has led to an intense pursuit for better tissue engineering regenerative strategies, where scaffolds play a major role. In this study, indirect printed hierarchical multilayered sca ffolds composed by a silk fibroin (SF) upper layer and an 80/20 (w/w) ratio of SF/ionic-doped β-tricalcium phosphate (TCP) bottom layer were developed. Furthermore, a comparative analysis between two types of sca ffolds pro- duced using di fferent SF concentrations, i.e., 8% (w/v) (Hi8) and 16% (w/v) (Hi16) was performed. In terms of architecture and morphology, the produced sca ffolds presented homogeneous porosity in both layers and no di fferences were observed when comparing both sca ffolds. A decrease in terms of mechanical performance of the sca ffolds was observed when SF concentration decreased from 16 to 8% (w/v). Hi16 revealed a static compressive modulus of 0.66 ± 0.05 MPa and dynamical mechanical properties ranging from 2.17 ± 0.25 to 3.19 ± 0.38 MPa. By its turn, Hi8 presented a compressive modulus of 0.27 ± 0.08 MPa and dynamical mechanical properties ranging from 1.03 ± 0.08 MPa to 1.56 ± 0.13 MPa. In vitro bioactivity studies showed formation of apatite crystals onto the surface of Hi8 and Hi16 bottom layers. Human meniscus cells (hMCs) and human primary osteoblasts were cultured separately onto the top layer (SF8 and SF16) and bottom layer (SF8/TCP and SF16/TCP) of the hierarchical sca ffolds Hi8 and Hi16, respectively. Both cell types showed good adhesion and proliferation as denoted by the live/dead staining, Alamar Blue assay and DNA quanti fication analysis. Subcutaneous implantation in mice revealed weak in flammation and sca ffold’s integrity. The hierarchical indirect printed SF sca ffolds can be promising candidate for meniscus TE sca ffolding applications due their suitable mechanical properties, good biological performance and possibility of being applied in a patient-speci fic approach.

Meniscus behaviors and capillary pressures in capillary channels having various cross-sectional geometries

A numerical study has been conducted to simulate the liquid/gas interface(meniscus) behaviors and capillary pressures in various capillary channels using the volume of fluid(VOF) method. Calculations are performed for four channels whose cross-sectional shapes are circle, regular hexagon, square and equilateral triangle and for four solid/liquid contact angles of 30°, 60°, 120° and 150°. No calculation is needed for the contact angle of 90° because the liquid/gas interface in this case can be thought to be a plane surface. In the calculations, the liquid/gas interface in each channel is assumed to have a flat surface at the initial time, it changes towards its due shape thereafter, which is induced by the combined action of the surface tension and contact angle. After experiencing a period of damped oscillation, it stabilizes at a certain geometry. The interface dynamics and capillary pressures are compared among different channels under three categories including the equal inscribed circle radius, equal area, and equal circumscribed circle radius. The capillary pressure in the circular channel obtained from the simulation agrees well with that given by the Young–Laplace equation, supporting the reliability of the numerical model. The channels with equal inscribed circle radius yield the closest capillary pressures, while those with equal circumscribed circle radius give the most scattered capillary pressures,with those with equal area living in between. A correlation is developed to calculate the equivalent radius of a polygonal channel, which can be used to compute the capillary pressure in such a channel by combination with the Young–Laplace equation.

SOME CHARACTERISTICS OF LIQUID METAL MENISCUS IN ELECTROMAGNETIC FIELD

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Meniscus fabrication of halide perovskite thin films at high throughput for large area and low-cost solar panels

Halide perovskites have rapidly attracted considerable attention due to unprecedented properties not seen in traditional semiconductors.In addition to their optoelectronic merits,one advantage of perovskite materials is their solution processability,which opens the door to low-cost and high throughput solution coating strategies for the commercialization of perovskite solar cells(PSCs).Here we review perovskite film fabrication by meniscus coating—a simple and readily scalable manufacturing technique,including blade coating and slot-die coating.We outline the fundamental fluid mechanisms of meniscus coating,discuss drying and crystallization of perovskite in the coating process,and provide an overview of recent progress in meniscus-coated PSCs.

Study on the Anisotropy of Meniscus in the Growing Sapphire

This study is aimed at predicting the relationship between the meniscus and the quality of the sapphire crystals produced by the micro-pulling and shoulder at cooled center （SAPMIC） technique. As with different orientations, the shapes of the meniscus vary, so an investigation into the anisotropy of the meniscus shapes is very important for the final quality of the sapphire crystal. An effective model to describe meniscus shapes and their formation process has been presented. The model has been applied to a sapphire crystal of 200 mm diameter in order to check its reliability. The results show that the model proves to be useful for forecasting the final shapes of the sapphire crystal made by the SAPMIC technique.

Arterial sunoly of the meniscus of knee ioint

The arterial supply of the genicular meniscus was studied with macro-microanatomical and histological examinations,translucent preparations and scanning electronmicroscopy.It was found that the menisci were supplied by the articular branches of thepopliteal artery except the lateral superior genicular branch and the descending genicularartery.Among them there were two genicular branches with independent stems from thepopliteal artery,named as the posterior medial and posterior lateral genicular artery,whichsupplied the posterior part of the corresponding meniscus.The genicular branchesanastomosed with each other to form a vascular circle around the menisci,and minutebranches from the circle formed an arterial network around the menisci and terminated incapillaries in 3 types of anastomotic forms.The surgical approach to the menisci and theprognosis of an injured meniscus were discussed on the basis of the arterial distributionsinside and outside of the menisci.

Simulation of liquid meniscus formation in the ionic liquid electrospray process

Though tremendous efforts have been made to investigate electrospray,some aspects,such as the evolution of the menisci on the micropores of porous emitter tips and the transient response of the meniscus during the polarity alternation,need to be further understood.This paper presents a computation fluid dynamics(CFD)model to describe the meniscus formation in the ionic liquid electrospray process.The CFD model,based on the Taylor–Melcher leaky dielectric fluid theory and the volume of fluid(VOF)method,is validated by experiments.The evolution of the meniscus on the basis of a micropore is presented using two typical ionic liquids,EMI-BF_(4) and EMI-Im.The influences of the pore size,flow rate and applied voltage on the formation of the meniscus have been studied.Results show that a larger pore is more likely to start emission,and the time consumed for liquid meniscus formation decreases with increasing applied voltage and flow rate.Further,it is found that alternation of polarity does not destroy the structure of the meniscus but retards the formation process,and a faster polarity alteration leads to a shorter delay in meniscus formation time.

Transport phenomena in meniscus region of horizontal single belt casting

The horizontal single belt casting(HSBC)incorporating a single-impingement feeding system was simulated with an improved numerical model.Physical experiments were carried out on the pilot-scale caster for validation.The results show that the meniscus turbulence neither comes from the tundish region,nor from the impingement between the melt and the moving belt.It is the moving belt that gives rise to this high turbulence region,and this region can stir the melt near the meniscus.The feeding system studied and the moving belt give rise to a buffer region,which can optimize casting parameter variations,especially melt depth changes in the tundish.The temperature change rate of the bottom surface of the strip is around 4 times faster than that of the upper surface.