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.

Specific Lethal Effects of Trace Neutral Red on Amoeba discoides and Trichodina

[ Objective] The aim of this study was to provide the reference for the artificial breeding of aquatic animals. [ Method] Amoeba discoides and Trichodina were treated by neutral red solution with different concentrations to observe the physiological activities of organelles in their death processes. Effects of neutral red solution on the growth of common aquatic animals such as Paramecium caudatum, Euglena viridis and Brachionus plicatilis were analyzed, and the specific lethal mechanism of trace neutral red to A. discoides and Trichodina was also preliminarily studied. [ Re- suit] The neutral red solution at a concentration of 0.5 mg/L damaged the physiological function of contractile vacuole in Trichodina and also had the specific lethal effect on Tdchodina, but it had no effect on the growth and reproduction of non-parasitic protozoa and B. p/icatilis. Neutral red so- lution with certain concentration led to disorder of the physiological functions of A. discoides, such as assimilation and rejection, which was a main factor that caused the death of A. discoides. [ Conclusion] With the advantages such as targeting, safety and easiness to be oxidized and decom- posed, neutral red is an ideal drug for treating the diseases caused by A. discoides and Trichodina, and its suitable concentration is 0. 5 mg/L.

Discoid medial meniscus of both knees:A case report

BACKGROUND Discoid meniscus is a congenital anomaly that typically affects the lateral meniscus.The appearance of the discoid medial meniscus in both knees is extremely rare,with an incidence of only 0.012%.CASE SUMMARY Our patient was a 30-year-old female.Under no obvious predisposing causes,she began to experience pain in both knees,which worsened while walking and squatting.The pain was aggravated after exercise,and joint flexion and extension activities were accompanied by knee snapping.Apley’s test was positive on physical examination,and there was a pressing pain in the medial articular space.Plain radiographs of both knees revealed no obvious abnormalities in the bilateral knee joint space.Partial meniscectomy as well as menisci reformation were performed on both knees under arthroscopy.Under the guidance of rehabilitation,the patient’s range of motion in both knees returned to normal without pain and knee snapping.CONCLUSION This study showed that the clinical manifestations of the discoid medial meniscus injury are identical to those of the conventional medial meniscus injury,and arthroscopic surgery is effective.

ARTHROSCOPIC TREATMENT FOR DISCOID LATERAL MENISCUS INJURY OF THE KNEE IN CHILDREN

Objective To study the arthroscopic treatment results for discoid lateral meniscus injury of the knee in children. Methods 74 children patients, including 98 knees underwent arthroscopic treatment due to discoid lateral meniscus injury were followed up. By Watanabe classification, incomplete discoid menis-cus was seen in 34 knees, complete in 42 and Wrisberg type in 22. The methods of treatment were partial, subtotal or total meniscectomy. The follow-up time ranged from 3 to 24 months, averaged 8 months. The re-sults were analyzed according to Lysholm knee evaluation method. Results By Lysholm evaluation the re-sults were excellent in 68 knees (69. 4%) and good in 30 (30. 6%). Conclusion Arthroscopic treatment is a reliable way for discoid lateral meniscus injury in children.

铝合金盘状零件离心铸造成形过程数值模拟及实验研究

运用ProCAST铸造仿真软件对离心铸造盘状零件充型和凝固过程进行数值模拟,研究了铸件可能产生的缺陷及位置,分析了缺陷产生的原因并优化铸造工艺。通过减少内浇口的数量,提高模具温度,减少热量散失,可以形成盘状零件的顺序凝固,有利于铸件质量的提高。试验表明,模拟结果与试验结果相吻合。

带凸缘的盘类零件的线切割加工工艺改进

为了提高线切割机床加工的找正精度和加工精度,以槽轮零件为例,对线切割机床加工带凸缘的盘类零件的传统工艺存在的问题及原因进行了分析,指出造成传统工艺精度不高的关键原因是工件的装夹问题,并对此提出了改进的方法:采用支撑板定位装夹工件。实践证明:采用该工艺后,装夹只需一次完成,省去穿丝找正过程,机床自身保证了定位、加工精度,并且该工艺节省了2/3装夹时间,极大降低了劳动强度,提高了效率。

Lessons Learned from a Case with Valgus Deformity of the Knee Following Partial Removal of Lateral Discoid Meniscus

Few studies have focused on the possible change in the axial alignment of the lower limb after lateral meniscectomy. Here, we present a patient with valgus deformity of the knee following the partial removal of lateral discoid meniscus. With the distal femur osteotomy and fixation, this complication was treated successfully. This case suggested that we should pay more attention to the axial alignment of the lower limb in patients with torn discoid lateral meniscus before meniscectomy, as a severe valgus inclination may develop in some of these patients.

Early development of Chondrus ocellatus Holm(Gigartinaceae,Rhodophyta)

Chondrus is an economically important red algae widely used for food and biochemical purpose.It early development is crucial for the culture and seedling propagation.We chose tetraspores and carpospores of Chondrus ocellatus as examples for experiment of the culture,induction and release in laboratory condition,aiming to understand early development of C.ocellatus and to apply in seedling production.Mature C.ocellatus were collected in Qingdao,China,from Nov.to Dec.2004.After the gametophyte and tetrasporophyte were brushed and washed with sterilized seawater,the algal materials were treated in 1.5%KI for 20 min,then were dried for lh to stimulate the releasing of spores.After the spores released overnight,it were cultured in PES medium,incubated at 18℃,10±2μmol/(m^(2).s^(1))in 12:12h(light:dark).The observation and recording under microscope were carried out.Continuous observation of the early development showed that both tetraspore and carpospore are similar to each other.In general,three stages of the early development were shown being division,discoid crust and seedling stages.To the division stage,the most obvious feature was the increasing of cell number;during the discoid crust stage,the discoid crust had a three-dimensional axis,and it began to differentiate into two types of cells:the basal cells and the apical cells;and to the seedling stage,several protuberances-like appeared on the discoid crusts and formed juvenile seedlings.Carpospores and tetraspores exhibited a similar development process that included division stage,discoid crust stage and seedling stage.

Behaviors of Spherical and Nonspherical Particles in a Square Pipe Flow

The lattice Boltzmann method(LBM)for multicomponent immiscible fluids is applied to the simulations of solid-fluid mixture flows including spherical or nonspherical particles in a square pipe at Reynolds numbers of about 100.A spherical solid particle is modeled by a droplet with strong interfacial tension and large viscosity,and consequently there is no need to track the moving solid-liquid boundary explicitly.Nonspherical(discoid,flat discoid,and biconcave discoid)solid particles are made by applying artificial forces to the spherical droplet.It is found that the spherical particle moves straightly along a stable position between the wall and the center of the pipe(the Segr´e-Silberberg effect).On the other hand,the biconcave discoid particle moves along a periodic helical path around the center of the pipe with changing its orientation,and the radius of the helical path and the polar angle of the orientation increase as the hollow of the concave becomes large.

Torn discoid lateral meniscus treated with arthroscopic meniscectomy:observations in 62 knees

Background Discoid lateral meniscus of the knee is common in Chinese population. There has been considerable debate about the best treatment for discoid lateral meniscus tears. The purpose of this study was to observe the effect of arthroscopic meniscectomy for the treatment of discoid lateral meniscus tears. Methods Between July 1999 and December 2004, arthroscopic meniscectomy was performed on 62 menisci of 57 patients with discoid lateral meniscus tears （52 unilateral, 5 bilateral）. 41 menisci were ＂complete discoid meniscus＂, 21 =incomplete＂. According to the extent of the meniscus tears, partial meniscectomy was performed on 52 knees, total meniscectomy on 7 knees, and partial meniscectomy combined with meniscus suture on 3 knees through an arthroscope After the operations, early rehabilitation training programs, including straight-leg-raising and range-of-motion exercises, were carried out. 51 patients were followed up for 1 year 2 months to 6 years 5 months （mean, 3 years 3 months）, 6 patients were lost. Lysholm-Ⅱ scoring system was used to assess the function of the knee joints before the operation and during the follow-up. Results The operations on all the 62 knees were successful without complications. The patients could walk normally after completing the 2-week postoperation rehabilitation program. After 3-4 weeks they could lead a normal life and participate in a moderate amount of sports or other physical activities. The mean Lysholm-Ⅱ score was 89 （60--100） during the follow-up, which was significantly higher than that before the operation （50, range 34-74; P〈0.01）. 88% of the patients achieved excellent or good clinical results. Conclusions Arthroscopic meniscectomy is an alternative for treatment of discoid lateral meniscus tears with minimal traumatic effects. It can achieve early mobilization and a low complication rate, as well as the preservation of the meniscus structure and functions to the largest extent. In combination with proper rehabilitation training, the operation can lead to good or excellent results.

Bilateral complete type discoid medial menisci： an adult patient with tears in both knees

Adiscoid meniscus, found in 1%-5% of the population, .is a human anatomic variant that usually affects thelateral meniscus of the knee. A discoid meniscus is more prone to injury than a normally shaped meniscus. In 1941,1 Cave and Staples first reported discoid medial meniscus. A bilateral discoid medial meniscus is extremely rare. The first case of bilateral discoid medial meniscus was reported by Murdoch in 1956.2 Since then, no more than 20 case reports of bilateral discoid medial menisci have been published to date, and most have been single case reports.3 Treatment of a torn discoid medial meniscus is similar to the treatment of a tom lateral meniscus of the knee. In cases where there is a significant disability, surgical excision may be required. Traditionally, the treatment of choice for symptomatic torn discoid meniscus has been open total or partial meniscectomy. Currently, arthroscopic partial meniscectomy is commonly used. Either meniscectomy or conservative method for treatment of a discoid medial meniscus with no tear is a debatable issue.3 A 39-year-old male was admitted to our hospital for intermittent swelling and pain of his right knee in 1999. He had a history of twisting injury on the affected knee 10 years before the admission, but the symptoms were not significant at that time. However, one year ago, on and off swelling with pain had gradually developed in his right knee, worsening with long distance walking and sports activities. Sometimes he felt that the knee was ＂giving way＂. Due to increasing discomfort interfering with his daily life, he was referred to us by his doctor. Physical examination of the patient＇s right knee showed atrophy of the musculus quadriceps femoris compared to the opposite side, medial tibiofemoral joint line tenderness, a range of motion from , and positive McMurray sign. The patient had no complaints on his opposite knee and physical examination did not reveal any abnormalities. MRI scan showed discoid medial meniscus with a horizontal cleavage tear while lateral meniscus appeared normal （Figure IA, B）. On 16th August 1999, arthroscopic examination of the right knee confirmed the presence of a complete discoid medial meniscus with horizontal cleavage and longitudinal tears and a normal lateral meniscus, while the tom discoid medial meniscus was reshaped by arthrotomy partial meniscectomy. The patient has been followed up for12 years, and the treatment outcome has been good and satisfactory to date. In 2011, the same patient was admitted again for intermittent swelling, pain and locking of his left knee. The patient experienced symptoms for 6 months with no previous history of injury. Physical examination of the left knee showed effusion of （＋＋） in the joint, atrophy of the musculus quadriceps femoris, medial tibiofemoral joint line tenderness, restriction of mobility, range of motion , and positive McMurray sign. MRI showed discoid medial meniscus with a horizontal cleavage in mid-body and posterior horn while the lateral meniscus appeared normal （Figure 1C, D）. Arthroscopic surgery was performed on 20th July 2011. Upon arthroscopic observation, discoid medial meniscus in the left knee was found to be the complete type with a horizontal cleavage in mid-body and longitudinal tears near the peripheral rim, but the lateral meniscus was normal. Discoid medial meniscus was reshaped by partial meniscectomy, using arthroscopic techniques （Figure 1E, F）. Discoid meniscus is found in 1%-5% of the population, with a slightly higher incidence in Asians. Discoid meniscus is an uncommon finding that typically affects the lateral meniscus of the knee, and the involvement of the medial meniscus bilaterally is extremely rare. A retrospective study was conducted by Dickason and colleagues in 1982,4 in which 8040 cases of medial menisci were analyzed. Among them, 10 were discoid menisci （0.12%）, and only one had bilateral involvement （0.012%）. Several studies on findings of bilateral discoid medial menisci have been reported by Asian doctors in recent years.3 To date, as few as 20 cases of bilateral discoid medial menisci have been reported. Interestingly, in the present case, the symptoms of the two knees appeared 12 years apart. We have confirmed the diagnosis of complete discoid medial menisci with tearing in the right knee in 1999 and the left knee in 2011.

The shape effect of reconstituted high-density lipoprotein nanocarriers on brain delivery and Aβ clearance

Accumulation of extracellular β-amyloid （Aβ） is crucial for the pathogenesis of Alzheimer＇s disease （AD）, and the development of novel therapeutic agents that can both accelerate Aβ clearance and inhibit the subsequent pathological cascades is regarded as a promising strategy for AD management. In our previous study, we have constructed discoidal apolipoprotein E3-reconstituted high-density lipoprotein （ApoE3-rHDL） as an efficient nanoplatform that can penetrate the blood-brain barrier and accelerate Aβ clearance for a combination treatment of AD. To further improve its drug loading capacity, we hypothesized that spherical rHDL might serve as a more powerful nanocarrier if it has the same brain delivery and Aβ clearance abilities as the discoidal rHDL does. To evaluate the potential of spherical rHDL as a promising alternative for the combination therapy for AD, here, we investigated the effect of the shape of rHDL on its brain delivery, Aβ clearance, and anti-AD efficacy. We found that spherical rHDL had stronger Aβ-binding affinity than discoidal rHDL did, more effectively facilitated microglial uptake and degradation of Aβ-42, achieved better brain distribution after intravenous administration, and more powerfully reduced Aβ deposition, decreased microglia activation, attenuated neurological damage, and rescued memory deficits in a mouse model of AD. Among the rHDLs evaluated, monosialotetrahexosyl ganglioside-incorporated spherical rHDL exerted the best effect. The findings of this study for the first time show a shape effect of an rHDL nanocarrier on its biological functions and suggest that a spherical lipoprotein-mimic nanocarrier may serve as a more efficient multifunctional nanoplatforrn for AD therapy.

Palaeoenvironmental and biostratigraphic implications of microbial mat-related structures:Examples from the modern Gulf of Cambay and the Precambrian Vindhyan Basin,India

A stretch of the modern hypersaline coastal plain of the Gulf of Cambay was chosen to examine the distribution of the microbial mat-related structures(MRS) on siliciclastic sediments in the intertidal and supratidal zones.The abundance of MRS increases from the lower intertidal zone to the upper supratidal zone while the type of MRS records a systematic change.While the lower intertidal zone exhibits wrinkle structures,sieve-like surfaces and patchy ripples in places,the upper intertidal zone exhibits diverse MRS related to reduced current activity on the mat layer and intermittent exposure.MRS in the upper intertidal zone include wrinkle structures,sieve-like surfaces,gas domes,reticulated surfaces,multi-directional ripples,patchy ripples,rolled-up mat fragments,setulfs and occasional petee ridges and cracked mat surfaces.The lower supratidal zone is characterized by increased occurrence of petee ridges,gas domes and cracked mat surfaces compared to the upper intertidal zone.The upper supratidal zone is distinguished by the presence of abundant cracked mat surfaces,petee ridges,gas domes and wrinkle structures.The presence of cm-scale,disc-shaped microbial colonies(DMC) with a variety of internal structures is a unique feature of the Gulf of Cambay study area.While wrinkle structures occur in all the coastal zones,setulfs occur close to the boundary between the upper intertidal and lower supratidal zones.An attempt has been made to compare the distribution of MRS in this modern environment with those in the ~1.6 Ga Chorhat Sandstone of the Vindhyan Supergroup for high-resolution palaeoenvironmental interpretation.The upper part of the intertidal segment of the Chorhat Sandstone is distinguished from its lower part by the presence of abundant cracked mat surfaces,petee ridges and gas domes in the former,while wrinkle structures,Kinneyia,rolled-up mat fragments,patchy ripples and multi-directional ripples are equally abundant in both parts.The lower part of the intertidal segment of the Chorhat Sandstone is thus analogous to the upper intertidal zone of the modern Gulf of Cambay environment,while the upper part of the Chorhat intertidal segment reflects prolonged exposure close to the high tide line.The bottom-most part of the intertidal segment of the Chorhat Sandstone with fewer MRS corresponds to the lower intertidal zone at Cambay.Inferred disc-shaped microbial fossils within Vindhyan sandstones are analogous to the DMC found in the modern environment and these features do not have any biostratigraphic implication.