Size Of Meniscus Research Articles

Midbody of the medial meniscus as a reference of preservation in partial meniscectomy for complete discoid lateral meniscus.

To evaluate the postoperative size of discoid lateral meniscus using magnetic resonance imaging (MRI) after partial meniscectomy relative to the size of medial meniscus midbody. This study included 48 patients who underwent arthroscopic partial meniscectomy with or without repair for symptomatic complete discoid meniscus. The intraoperative size of midbody of medial meniscus was used as a reference for partial meniscectomy. MRIs were performed pre- and postoperatively. Quantitative evaluations of the height, width, extrusion of the meniscus, and relative percentage of extrusion in the coronal and sagittal planes were completed. Demographic data, preoperative shift, type of shift, and operative technique were analyzed while considering the remaining meniscus. Logistic regression analyses were used. The mean remaining discoid meniscal width in the coronal plane of MRI was not significantly different from the width of midbody of medial meniscus (9.1 ± 4.2mm vs. 9.4 ± 1.4mm, n.s.) Absolute meniscal extrusion and relative percentage of extrusion in the coronal plane and the ratio of t meniscus in sagittal plane of the final MRI were significantly increased as compared with the preoperative MRI. Preoperative shift was a risk factor for the reduction of remaining meniscal width (odds ratio 11.997, p = 0.016, 95% CI 1.586-90.737). The size of midbody of medial meniscus could be a reference for partial meniscectomy in symptomatic complete discoid meniscus. Preoperative shift represents a risk factor for decreased remaining meniscal width. These findings could be helpful in ensuring appropriate surgical planning and explaining poor prognostic factors. Prospective cohort study, Level II.

Role of Vapor Mass Transfer in Flow Coating of Colloidal Dispersions in the Evaporative Regime.

In flow-coating processes at low substrate velocity, solvent evaporation occurs during the film withdrawal and the coating process directly yields a dry deposit. In this regime, often referred to as the evaporative regime, several works performed on blade-coating-like configurations have reported a deposit thickness hd proportional to the inverse of the substrate velocity V. Such a scaling can be easily derived from simple mass conservation laws, assuming that evaporation occurs on a constant distance, referred to as the evaporation length, noted Lev in the present paper and of the order of the meniscus size. However, the case of colloidal dispersions deserves further attention. Indeed, the coating flow leads to a wet film of densely packed colloids before the formation of the dry deposit. This specific feature is related to the porous nature of the dry deposit, which can thus remain wet when capillary forces are strong enough to prevent the receding of the solvent through the pores of the film (the so-called pore-emptying). The length of this wet film may possibly be much larger than the meniscus size, therefore modifying the solvent evaporation rate, as well as the scaling hd ∼ 1/V. This result was suggested recently by different groups using basic modeling and assuming for simplicity a uniform evaporation rate over the wet film. In this article, we go a step further and investigate the effect of multidimensional vapor mass transfer in the gas phase on Lev and hd in the specific case of colloidal dispersions. Using simplified models, we first provide analytical expressions in asymptotic cases corresponding to 1D or 2D diffusive vapor transport. These theoretical investigations then led us to show that Lev is independent of the evaporation rate amplitude, and roughly independent of its spatial distribution. Conversely, hd strongly depends on the characteristics of vapor mass transfer in the gas phase, and different scaling laws are obtained for the 1D or the 2D case. These theoretical findings are finally tested by comparison with experimental results supporting our theoretical simplified approach.

The effects of geometric uncertainties on computational modelling of knee biomechanics.

The geometry of the articular components of the knee is an important factor in predicting joint mechanics in computational models. There are a number of uncertainties in the definition of the geometry of cartilage and meniscus, and evaluating the effects of these uncertainties is fundamental to understanding the level of reliability of the models. In this study, the sensitivity of knee mechanics to geometric uncertainties was investigated by comparing polynomial-based and image-based knee models and varying the size of meniscus. The results suggested that the geometric uncertainties in cartilage and meniscus resulting from the resolution of MRI and the accuracy of segmentation caused considerable effects on the predicted knee mechanics. Moreover, even if the mathematical geometric descriptors can be very close to the imaged-based articular surfaces, the detailed contact pressure distribution produced by the mathematical geometric descriptors was not the same as that of the image-based model. However, the trends predicted by the models based on mathematical geometric descriptors were similar to those of the imaged-based models.

Establishment of novel meniscal scaffold structures using polyglycolic and poly-l-lactic acids.

The purpose of this study was to evaluate various types of meniscus scaffolds that mimic the meniscus structure, and to establish a novel cell-free meniscus scaffold with polyglycolic acid or poly-l-lactic acid. Four types of scaffolds were implanted into Japanese white rabbits: poly-l-lactic acid sponge poly-l-lactic acid, PGA-coated PLLA sponge, PGA lamination, and film-coated PGA lamination. Samples were harvested at 8 and 12 weeks after implantation, and a compression stress test was performed. The meniscus size and Ishida scores were evaluated for regenerated tissue. Immunohistochemistry was analyzed by anti-type I, II and X collagen antibodies to investigate the structure of the regenerated tissue, and by anti-iNOS antibody to investigate the inflammatory tissue of the meniscus. The cell nuclei of lymphocytes and foreign body multinucleated giant cells were counted in hematoxylin and eosin staining. Modified Mankin scores for cartilage degeneration were used for assessment after Safranin-O/Fast Green staining. The biomechanical test showed that l- and film-coated PGA lamination exhibited greater strength than s- and PGA-coated PLLA sponge. At 12 weeks, the size of meniscus and the Ishida score in implanted film-coated PGA lamination were improved significantly compared with the defect groups. The type II collagen staining intensity in the PGA lamination lamination is significantly higher than the defect at eight weeks. The staining intensity of iNOS and number of lymphocytes significantly increased in sponge poly-l-lactic acid at eight weeks, and increased in p-PLLA at 12 weeks. Foreign body multinucleated giant cells in implantation groups appeared, especially at eight weeks. The Mankin score for film-coated PGA lamination was significantly lower than for the defect at 12 weeks. Novel meniscal scaffolds especially PGA should possess not only biological but also biomechanical functions. In conclusions, film-coated PGA lamination was the beneficial property for meniscus scaffold from the points of better biomechanical function, good regeneration, and less inflammation with chondroprotective effects.

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

To evaluate the change in the thickness and width of the residual meniscus using magnetic resonance imaging (MRI) in patients who underwent arthroscopic partial meniscectomy for discoid lateral meniscus (DLM), to assess whether the degeneration of the articular cartilage in the lateral compartment of the knee progressed, and to evaluate clinical results. Among the patients who underwent arthroscopic partial meniscectomy for DLM between January 1997 and December 2011, those who were aged 40 or below at surgery were followed up for at least 3years, and received at least 2 follow-up MRIs that were retrospectively reviewed. MRIs were done in symptomatic knees. Using MRI, the relative thickness and width were measured in the anterior horn, midportion, and posterior horn. To determine whether the degeneration of the lateral compartment would progress, the articular cartilage was graded based on the Outerbridge classification in MRIs. The clinical results were evaluated using the Lysholm score. A total of 20 patients (21knees) were included. The average follow-up period was 6.8years. In residual meniscus, the relative thickness of themidportion decreased from 9.0% ± 2.4% to 7.3% ± 2.3% (P < .001), the relative thickness of the anterior horndecreased from 15.6% ± 4.3% to 14.3% ± 6.7% (P= .030), and the relative thickness of the posterior horndecreased from 20.0%± 4.4% to 16.7% ± 6.7% (P= .019). A decrease in the relative width was observed in the midportion (12.4% ± 4.8% to 10.9% ± 4.9%, P= .003). No significant changes in size were observed in the medial meniscus. A progression of degeneration in the lateral compartment was observed. However, the clinical results did not present significant changes. In symptomatic patients after arthroscopic partial meniscectomy for DLM, the thickness and width of the residual meniscus decreases over time. The arthritic change of the lateral compartment of the knee progressed. However, the change in the size of the residual meniscus was of unknown clinical significance. Level IV, therapeutic case series.

Abnormal Mechanical Loading Induces Cartilage Degeneration by Accelerating Meniscus Hypertrophy and Mineralization After ACL Injuries In Vivo

Background: Although patients with an anterior cruciate ligament (ACL) injury have a high risk of developing posttraumatic osteoarthritis (PTOA), the role of meniscus hypertrophy and mineralization in PTOA after an ACL injury remains unknown. Purpose/Hypothesis: The purpose of this study was to determine if menisci respond to abnormal loading and if an ACL injury results in meniscus hypertrophy and calcification. The hypotheses were that (1) abnormal mechanical loading after an ACL injury induces meniscus hypertrophy and mineralization, which correlates to articular cartilage damage in vivo, and (2) abnormal mechanical loading on bovine meniscus explants induces the overexpression of hypertrophic and mineralization markers in vitro. Study Design: Controlled laboratory study. Methods: In vivo guinea pig study (hypothesis 1): Three-month-old male Hartley guinea pigs (n = 9) underwent ACL transection (ACLT) on the right knee; the left knee served as the control. Calcification in the menisci was evaluated by calcein labeling 1 and 5 days before knee harvesting at 5.5 months. Cartilage and meniscus damage and mineralization were quantified by the Osteoarthritis Research Society International score and meniscus grade, respectively. Indian hedgehog (Ihh), matrix metalloproteinase–13 (MMP-13), collagen type X (Col X), progressive ankylosis homolog (ANKH), ectonucleotide pyrophosphatase/phosphodiesterase–1 (ENPP1), alkaline phosphatase (ALP), inorganic pyrophosphate (PPi), and inorganic phosphate (Pi) concentrations were evaluated by immunohistochemistry and enzyme-linked immunosorbent assay. In vitro bovine meniscus explant study (hypothesis 2): Bovine meniscus explants were subjected to 25% strain at 0.3 Hz for 1, 2, and 3 hours. Cell viability was determined using live/dead staining. The levels of mRNA expression and protein levels were measured using real-time quantitative reverse transcription polymerase chain reaction and Western blot after 24, 48, and 72 hours in culture. The conditioned medium was collected for sulfated glycosaminoglycan (GAG) release and Pi/PPi assay. Results: In vivo guinea pig study: Meniscus size and area as well as intensity of meniscus calcification were significantly increased in the ACLT group compared with the control group. Both calcified area and intensity were correlated with cartilage damage in the ACLT group (meniscus calcified area: r = 0.925, P < .0001; meniscus calcified intensity: r = 0.944, P < .0001). Ihh, MMP-13, Col X, ANKH, ENPP1, and ALP expression were increased in the ACLT group compared with the control group. The Pi level and Pi/PPi ratio increased by 63% and 42%, respectively, in the ACLT group compared with the control group. In vitro bovine meniscus explant study: Cell death was found in the superficial zone of the bovine meniscus explants after loading for 3 hours. The mRNA expression and protein levels of MMP-13, ANKH, ENPP1, and ALP were up-regulated in all 3-hour loaded samples. The Pi/PPi ratio and sulfated GAG content in the culture medium were increased in the 3-hour loaded group. Conclusion: Meniscus hypertrophy and mineralization correlated to cartilage degeneration after ACL injuries. Clinical Relevance: The study data suggest that the suppression of meniscus hypertrophy and calcification may decrease the risk of PTOA after ACL injuries.

Shape and Effective Spring Constant of Liquid Interfaces Probed at the Nanometer Scale: Finite Size Effects.

We investigate the shape and mechanical properties of liquid interfaces down to nanometer scale by atomic force microscopy (AFM) and scanning electron microscopy (SEM) combined with in situ micromanipulation techniques. In both cases, the interface is probed with a cylindrical nanofiber with radius R of the order of 25-100 nm. The effective spring constant of the nanomeniscus oscillated around its equilibrium position is determined by static and frequency-modulation (FM) AFM modes. In the case of an unbounded meniscus, we find that the effective spring constant k is proportional to the surface tension γ of the liquid through k = (0.51 ± 0.06)γ, regardless of the excitation frequency from quasi-static up to 450 kHz. A model based on the equilibrium shape of the meniscus reproduces well the experimental data. Electron microscopy allowed to visualize the meniscus profile around the fiber with a lateral resolution of the order of 10 nm and confirmed its catenary shape. The influence of a lateral confinement of the interface is also investigated. We showed that the lateral extension L of the meniscus influences the effective spring constant following a logarithmic evolution k ∼ 2πγ/ln(L/R) deduced from the model. This comprehensive study of liquid interface properties over more than 4 orders of magnitude in meniscus size shows that advanced FM-AFM and SEM techniques are promising tools for the investigation of mechanical properties of liquids down to nanometer scale.

Synovial mesenchymal stem cells promote meniscus regeneration augmented by an autologous Achilles tendon graft in a rat partial meniscus defect model.

Although meniscus defects and degeneration are strongly correlated with the later development of osteoarthritis, the promise of regenerative medicine strategies is to prevent and/or delay the disease's progression. Meniscal reconstruction has been shown in animal models with tendon grafting and transplantation of mesenchymal stem cells (MSCs); however, these procedures have not shown the same efficacy in clinical studies. Here, our aim was to investigate the ability of tendon grafts pretreated with exogenous synovial-derived MSCs to prevent cartilage degeneration in a rat partial meniscus defect model. We removed the anterior half of the medial meniscus and grafted autologous Achilles tendons with or without a 10-minute pretreatment of the tendon with synovial MSCs. The meniscus and surrounding cartilage were evaluated at 2, 4, and 8 weeks (n = 5). Tendon grafts increased meniscus size irrespective of synovial MSCs. Histological scores for regenerated menisci were better in the tendon + MSC group than in the other two groups at 4 and 8 weeks. Both macroscopic and histological scores for articular cartilage were significantly better in the tendon + MSC group at 8 weeks. Implanted synovial MSCs survived around the grafted tendon and native meniscus integration site by cell tracking assays with luciferase+, LacZ+, DiI+, and/or GFP+ synovial MSCs and/or GFP+ tendons. Flow cytometric analysis showed that transplanted synovial MSCs retained their MSC properties at 7 days and host synovial tissue also contained cells with MSC characteristics. Synovial MSCs promoted meniscus regeneration augmented by autologous Achilles tendon grafts and prevented cartilage degeneration in rats. Stem Cells 2015;33:1927–1938

Adhesion Behavior of a Grating at a Single Location by Using an AFM Flat Tip Under Different Conditions

Adhesion forces were determined by recording force–displacement curves using a flat tip with an atomic force microscope. The outcomes show that the adhesion behavior at a single location depends largely on contact geometry, surface topography, instrumental parameters, and the environment. Moreover, these factors are mutually coupled with each other to determine the final adhesion force. A special surface structure will lead to special adhesion behaviors by repetitive measurements. The adhesion forces are grouped into several levels. In dry nitrogen (with charges removal), the adhesion force in each level first increases and then decreases slightly. In dry nitrogen and under ambient conditions, the adhesion force in different levels increases with measurement number, and jumps between different levels. The increasing trend was ascribed to the charge accumulation and the increased size of the capillary meniscus, respectively. The charges will increase only after contact and separation and have an additive effect. When the charges are saturated, the adhesion force becomes stable. Some special adhesion behaviors are also observed in the experiments. The fluctuation behaviors of adhesion in a single cluster under different conditions are different, which was attributed to the dominant force and the environment.

Longitudinal change in quantitative meniscus measurements in knee osteoarthritis--data from the Osteoarthritis Initiative.

We aimed to apply 3D MRI-based measurement technology to studying 2-year change in quantitative measurements of meniscus size and position. Forty-seven knees from the Osteoarthritis Initiative with medial radiographic joint space narrowing had baseline and 2-year follow-up MRIs. Quantitative measures were obtained from manual segmentation of the menisci and tibia using coronal DESSwe images. The standardized response mean (SRM = mean/SD change) was used as measure of sensitivity to longitudinal change. Medial tibial plateau coverage decreased from 34.8% to 29.9% (SRM -0.82; p < 0.001). Change in medial meniscus extrusion in a central image (SRM 0.18) and in the central five slices (SRM 0.22) did not reach significance, but change in extrusion across the entire meniscus (SRM 0.32; p = 0.03) and in the relative area of meniscus extrusion (SRM 0.56; p < 0.001) did. There was a reduction in medial meniscus volume (10%; p < 0.001), width (7%; p < 0.001), and height (2%; p = 0.08); meniscus substance loss was strongest in the posterior (SRM -0.51; p = 0.001) and weakest in the anterior horn (SRM -0.15; p = 0.31). This pilot study reports, for the first time, longitudinal change in quantitative 3D meniscus measurements in knee osteoarthritis. It provides evidence of improved sensitivity to change of 3D measurements compared with single slice analysis. • First longitudinal MRI-based measurements of change of meniscus position and size. • Quantitative longitudinal evaluation of meniscus change in knee osteoarthritis. • Improved sensitivity to change of 3D measurements compared with single slice analysis.

A diffusive ink transport model for lipid dip-pen nanolithography.

Despite diverse applications, phospholipid membrane stacks generated by dip-pen nanolithography (DPN) still lack a thorough and systematic characterization that elucidates the whole ink transport process from writing to surface spreading, with the aim of better controlling the resulting feature size and resolution. We report a quantitative analysis and modeling of the dependence of lipid DPN features (area, height and volume) on dwell time and relative humidity. The ink flow rate increases with humidity in agreement with meniscus size growth, determining the overall feature size. The observed time dependence indicates the existence of a balance between surface spreading and the ink flow rate that promotes differences in concentration at the meniscus/substrate interface. Feature shape is controlled by the substrate surface energy. The results are analyzed within a modified model for the ink transport of diffusive inks. At any humidity the dependence of the area spread on the dwell time shows two diffusion regimes: at short dwell times growth is controlled by meniscus diffusion while at long dwell times surface diffusion governs the process. The critical point for the switch of regime depends on the humidity.

Immediate impact of hyaluronic and methylcellulose artificial tears on tear film stability

AbstractPurpose To evaluate immediate impact of hyaluronic and methylcellulose artificial tears on tear film stability.Methods We performed keratography with tear film analyze in 21 volunteers using Keratograph 4 (Oculus, Germany). After base measurement, volunteers received topical artificial tears drops containing 0.15% Sodium Hyaluronate into right eye and 0.5% Carboxyl Methylcellulose into left eye. After 15 and 30 minutes keratography measurements were repeated.Results In keratography analyzes we observed 4 types of tear film instability, short‐time break‐up on small area or big area, long‐time break‐up on small or big area. Mean size of tear meniscus in right eyes before drops was 0.3±0.1 mm and 0.32±0.09/0.33±0.09 mm 15/30 minutes after hyaluronic drops respectively (p&lt;0.05, Kruskal‐Wallis test). In left eyes tear meniscus size was 0.32±0.1/0.33±0.1/0.34±0.1 mm respectively before and after methylcellulose drops (p&lt;0.05, Kruskal‐Wallis test). First and mean non‐invasive break‐up‐time in right eyes was 10.7/16.8 sec before drops and 12/18; 12/17 – 15 and 30 minutes after hyaluronic drops application (p&gt;0.05, Kruskal‐Wallis test). In left eyes these parameters were 12/16; 13/18 and 13/17 sec respectively before and after methylcellulose drops (p&gt;0.05, Kruskal‐Wallis test).Conclusion Immediate impact of hyaluronic and methylcellulose artificial tears on tear film seems to be related more to increase of tear meniscus size, not to tear film break‐up time or break‐up surface. Keratograhy measurements allow for detail analyzes of tear film state, which includes not only break‐up time but also break‐up surface, which could be novel indicator for tear film stability impossible to measure in classic slit lamp.

Foam separation selectivity conditioned by the chemically attached agent

It is hypothesized that the critical thickness of rupture of a liquid film between air bubble and mineral particle depends on potential and size of area occupied by nanobubble. It is shown that the critical thickness of film equals the height of meniscus formed under rupture. The size and shape of meniscus are characterized by its neck radius and contact angle. The proposed hypothesis is based on the assumption that the size of initial meniscus neck is connected with the diameter of attachment area of nanobubble. There are no nanobubbles on the surface of hydrophilic minerals, and the liquid film rupture is hampered in this case. Since liquid film stability is mainly affected by hydrophobic interaction, the liquid film rupture thickness is larger on hydrophilic minerals than on hydrophobic minerals. Selectivity of foam separation of minerals, governed by the chemically attached agents, depends on the ratio of the critical rupture thicknesses of the liquid film.

Contribution of regional 3D meniscus and cartilage morphometry by MRI to joint space width in fixed flexion knee radiography—A between-knee comparison in subjects with unilateral joint space narrowing

BackgroundRadiographic joint space width (JSW) is considered the reference standard for demonstrating structural therapeutic benefits in knee osteoarthritis. Our objective was to determine the proportion by which 3D (regional) meniscus and cartilage measures explain between-knee differences of JSW in the fixed flexion radiographs. MethodsSegmentation of the medial meniscus and tibial and femoral cartilage was performed in double echo steady state (DESS) images. Quantitative measures of meniscus size and position, femorotibial cartilage thickness, and radiographic JSW (minimum, and fixed locations) were compared between both knees of 60 participants of the Osteoarthritis Initiative, with strictly unilateral medial joint space narrowing (JSN). Statistical analyses (between-knee, within-person comparison) were performed using regression analysis. ResultsA strong relationship with side-differences in minimum and a central fixed location JSW was observed for percent tibial plateau coverage by the meniscus (r=.59 and .47; p<.01) and central femoral cartilage thickness (r=.69 and .75; p<.01); other meniscus and cartilage measures displayed lower coefficients. The correlation of central femoral cartilage thickness with JSW (but not that of meniscus measures) was greater (r=.78 and .85; p<.01) when excluding knees with non-optimal alignment between the tibia and X-ray beam. Conclusion3D measures of meniscus and cartilage provide significant, independent information in explaining side-differences in radiographic JSW in fixed flexion radiographs. Tibial coverage by the meniscus and central femoral cartilage explained two thirds of the variability in minimum and fixed location JSW. JSW provides a better representation of (central) femorotibial cartilage thickness, when optimal positioning of the fixed flexion radiographs is achieved.

Intraarticular injection of synovial stem cells promotes meniscal regeneration in a rabbit massive meniscal defect model

We investigated whether single intraarticular injection of synovial MSCs enhanced meniscal regeneration in a rabbit massive meniscal defect model. Synovium were harvested from the knee joint of rabbits, and the colony-forming cells were collected. Two weeks after the anterior half of the medial menisci were excised in both knees, 1 × 10(7) MSCs in 100 μl PBS were injected into the right knee. The MSC and control groups were compared macroscopically and histologically at 1, 3, 4, and 6 months (n = 4). Articular cartilage of the medial femoral condyle was also evaluated histologically at 6 months. Multipotentiality of the colony-forming cells was confirmed. Injected MSCs labeled with DiI were detected and remained in the meniscal defect at 14 days. The size of meniscus in the MSC group was larger than that in the control group at 1 and 3 months. The difference of the size between the two groups was indistinct at 4 and 6 months. However, histological score was better in the MSC group than in the control group at 1, 3, 4, and 6 months. Macroscopically, the surface of the medial femoral condyle in the control group was fibrillated at 6 months, while looked close to intact in the MSC group. Histologically, defect or thinning of the articular cartilage with sclerosis of the subchondral bone was observed in the control group, contrarily articular cartilage and subchondral bone were better preserved in the MSC group. Synovial MSCs injected into the knee adhered around the meniscal defect, and promoted meniscal regeneration in rabbits.

Meniscus matching: Evaluation of direct anatomical, indirect radiographic, and photographic methods in 10 cadaver knees

When performing meniscus transplantation, allograft size must be carefully matched to the host knee anatomy. The radiographic method devised by Pollard et al. is the current reference standard for meniscus size matching. The primary objective of this study was to compare the accuracy of radiographic measurement according to Pollard, direct anatomic measurement, and photographic measurement. Anatomic and photographic allograft size measurement is as reliable as radiographic host-knee sizing according to Pollard et al. Three methods for measuring meniscal width and length based on reliable landmarks were assessed in 10 cadaver knees: direct measurement of anatomic specimens, measurement of photographs, and the radiographic method described by Pollard et al. No significant differences were found between the anatomic and radiographic methods, whereas the anatomic and photographic methods produced significantly different results. Compared to the anatomic method, mean overall measurement error was 7.9% for the radiographic method and 24.1% for the photographic method. The photographic method used in everyday practice during allograft harvesting is not reliable. Correcting for magnification bias might improve the performance of the photographic method. The radiographic method described by Pollard et al. is acceptable, with a margin of error of about 10%, which is considered tolerable. In practice, however, the radiographic method is burdensome to use. The best measurement method is direct measurement of the specimen during allograft harvesting. Level IV.

There is no relation between mild malalignment and meniscal extrusion in trauma emergency patients

ObjectiveTo evaluate whether an alteration of the lower limb axis is associated with meniscal extrusion. Materials and Methods: Ninety-four patients who had complained of knee pain with good knee function and had a knee magnetic resonance image (MRI) and a full-length X-ray taken of the lower limb were included in the study. Meniscal extrusion was measured in the coronal MRI. Subluxation of the meniscus was considered minor or physiological if ≤3 mm, and major if >3 mm. The extrusion as a percentage of meniscus size was also calculated. Knee alignment (varus, negative value; valgus, positive value) was correlated with the presence of minor and major extrusion. ResultsThere were varus knees in 61 cases (58.7%), with a mean measured deviation of −2.63°. Valgus knees were observed in 27 knees (26%) and had a mean deviation of 2.22°. The medial meniscus showed major extrusion in 18 cases (17.3%). It corresponded to 44.7% of the meniscus size. The lateral menisci showed no subluxation in most cases. There was no correlation between alignment and meniscal extrusion in this series, either for the medial meniscus (p = 0.760) or for the lateral meniscus (p = 0.381). ConclusionsIn patients complaining of knee pain with good knee function, there is no relationship between mild malalignment and the degree of meniscus extrusion.

Influence of geometrical defects on the mechanical behaviour of hollow-sphere structures

Hollow-sphere structures could represent an alternative to classical cellular materials, such as metal foams or honeycombs, for various structural applications; such stainless steel random structures are already on the market. One advantage of hollow-sphere structures unlike metal foams ensues from the possibility to stack the spheres regularly, even if in the literature there are only examples of limited size regular stackings for the moment. Higher mechanical properties than those of random cellular structures are expected for such regular structures according to modelling studies. Nevertheless, because of the difficulty in processing perfect regular stackings, it seems to be critical to study the influence of architectural defects on the overall mechanical behaviour of these cellular structures. Emphasis is on geometrical defects by introducing some dispersions on the sphere thickness and the meniscus size. Influences of both the magnitude of dispersion and the distribution of the defects on the mechanical behaviour of hollow-sphere structure are investigated. Especially, collapse mechanisms resulting from plasticity and their inhomogeneous localisation in the structure are studied in details. The case of periodic defects is addressed too in order to compare the mechanical response of infinite stackings to that of finite ones. This work highlights the significant influence of the defects on the effective mechanical behaviour of hollow-sphere structures. Most of the time, geometrical dispersion and defects are detrimental for the stacking behaviour, especially when understructures made of the defective hollow spheres or menisci are observed.

Effects of tip-substrate gap, deposition temperature, holding time, and pull-off velocity on dip-pen lithography investigated using molecular dynamics simulation

The process parameters in the dip-pen nanolithography process, including tip-substrate gap, deposition temperature, holding time, and pull-off velocity are evaluated in terms of the mechanism of molecular transference, alkanethiol meniscus characteristic, surface adsorbed energy, and pattern formation using molecular dynamics simulations. The simulation results clearly show that the optimum deposition occurs at a smaller tip-substrate gap, a slower pull-off velocity, a higher temperature, and a longer holding time. The pattern area increases with decreasing tip-substrate gap and increasing deposition temperature and holding time. With an increase in deposition temperature, the molecular transfer ability significantly increases. Pattern height is a function of meniscus length. When the pull-off velocity is decreased, the pattern height increases. The height of the neck in meniscus decreases and the neck width increases with holding time. Meniscus size increases with increasing deposition temperature and holding time.

Quantification of tibial coverage, meniscus position and meniscus size in knees with and without joint space narrowing - data from the OA initiative

Quantification of tibial coverage, meniscus position and meniscus size in knees with and without joint space narrowing - data from the OA initiative