Regeneration of whole meniscus using meniscal cells and polymer scaffolds in a rabbit total meniscectomy model

The current treatments of meniscal lesion in knee joint are not perfect to prevent adverse effects of meniscus injury. Tissue engineering of meniscus using meniscal cells and polymer scaffolds could be an alternative option to treat meniscus injury. This study reports on the regeneration of whole medial meniscus in a rabbit total meniscectomy model using the tissue engineering technique. Biodegradable scaffolds in a meniscal shape were fabricated from polyglycolic acid (PGA) fiber meshes that were mechanically reinforced by bonding PGA fibers at cross points with 75:25 poly(lactic-co-glycolic acid). The compressive modulus of the bonded PGA scaffold was 28-fold higher than that of nonbonded scaffold. Allogeneic meniscal cells were isolated from rabbit meniscus biopsy and cultured in vitro. The expanded meniscal cells were seeded onto the polymer scaffolds, cultured in vitro for 1 week, and transplanted to rabbit knee joints from which medial menisci were removed. Ten or 36 weeks after transplantation, the implants formed neomenisci with the original scaffold shape maintained approximately. Hematoxylin and eosin staining of the sections of the neomenisci at 6 and 10 weeks revealed the regeneration of fibrocartilage. Safranin-O staining showed that abundant proteoglycan was present in the neomenisci at 10 weeks. Masson's trichrome staining indicated the presence of collagen. Immunohistochemical analysis showed that the presence of type I and II collagen in neomenisci at 10 weeks was similar to that of normal meniscal tissue. Biochemical and biomechanical analyses of the tissue-engineered menisci at 36 weeks were performed to determine the quality of the tissue-engineered menisci. Tissue-engineered meniscus showed differences in collagen content and aggregate modulus in comparison with native meniscus. This study demonstrates, for the first time, the feasibility of regenerating whole meniscal cartilage in a rabbit total meniscectomy model using the tissue engineering method.     

Regeneration of whole meniscus using meniscal cells and polymer scaffolds in a rabbit total meniscectomy model

The current treatments of meniscal lesion in knee joint are not perfect to prevent adverse effects of meniscus injury. Tissue engineering of meniscus using meniscal cells and polymer scaffolds could be an alternative option to treat meniscus injury. This study reports on the regeneration of whole medial meniscus in a rabbit total meniscectomy model using the tissue engineering technique. Biodegradable scaffolds in a meniscal shape were fabricated from polyglycolic acid (PGA) fiber meshes that were mechanically reinforced by bonding PGA fibers at cross points with 75:25 poly(lactic-co-glycolic acid). The compressive modulus of the bonded PGA scaffold was 28-fold higher than that of nonbonded scaffold. Allogeneic meniscal cells were isolated from rabbit meniscus biopsy and cultured in vitro. The expanded meniscal cells were seeded onto the polymer scaffolds, cultured in vitro for 1 week, and transplanted to rabbit knee joints from which medial menisci were removed. Ten or 36 weeks after transplantation, the implants formed neomenisci with the original scaffold shape maintained approximately. Hematoxylin and eosin staining of the sections of the neomenisci at 6 and 10 weeks revealed the regeneration of fibrocartilage. Safranin-O staining showed that abundant proteoglycan was present in the neomenisci at 10 weeks. Masson's trichrome staining indicated the presence of collagen. Immunohistochemical analysis showed that the presence of type I and II collagen in neomenisci at 10 weeks was similar to that of normal meniscal tissue. Biochemical and biomechanical analyses of the tissue-engineered menisci at 36 weeks were performed to determine the quality of the tissue-engineered menisci. Tissue-engineered meniscus showed differences in collagen content and aggregate modulus in comparison with native meniscus. This study demonstrates, for the first time, the feasibility of regenerating whole meniscal cartilage in a rabbit total meniscectomy model using the tissue engineering method.     

Meniscal regeneration using tissue engineering with a scaffold derived from a rat meniscus and mesenchymal stromal cells derived from rat bone marrow

The purpose of this study was to regenerate a meniscus using a scaffold from a normal meniscus and mesenchymal stromal cells derived from bone marrow (BM-MSCs). Thirty Sprague-Dawley rat menisci were excised and freeze-thawed three times with liquid nitrogen to kill the original meniscal cells. Bone marrow was aspirated from enhanced green fluorescent protein transgenic Sprague-Dawley rats. BM-MSCs were isolated, cultured for 2 weeks, and 2 x 10(5) cells were then seeded onto the meniscal scaffolds. Using a fluorescent microscope and immunohistochemical staining, repopulation of enhanced green fluorescent protein positive cells was observed in the superficial zone of the scaffold after 1 week of culture, and then in the deep zone after 2 weeks. At 4 weeks, expression of extracellular matrices was detected histologically and expression of mRNA for aggrecan and type X collagen was detected. Stiffness of the cultured tissue, assessed by the indentation stiffness test, had increased significantly after 2 weeks in culture, and approximated the stiffness of a normal meniscus. From this study, we conclude that a scaffold derived from a normal meniscus seeded with BM-MSCs can form a meniscus approximating a normal meniscus.     

The menisci of the knee joint. Anatomical and functional characteristics, and a rationale for clinical treatment

The menisci and their insertions into bone (entheses) represent a functional unit. Thanks to their firm entheses, the menisci are able to distribute loads and therefore reduce the stresses on the tibia, a function which is regarded essential for cartilage protection and prevention of osteoarthrosis. The tissue of the hypocellular meniscal body consists mainly of water and a dense elaborate type I collagen network with a predominantly circumferential alignment. The content of different collagens, proteoglycans and nonproteoglycan proteins shows significant regional variations probably reflecting functional adaptation. The meniscal horns are attached via meniscal insertional ligaments mainly to tibial bone. At the enthesis, the fibres of the insertional ligaments attach to bone via uncalcified and calcified fibrocartilages. This anatomical configuration of gradual transition from soft to hard tissue, which is identical to other ligament entheses, is certainly essential for normal mechanical function and probably protects this vulnerable transition between 2 biomechanically different tissues from failure. Clinical treatment of meniscal tears needs to be based on these special anatomical and functional characteristics. Partial meniscectomy will preserve some of the load distribution function of the meniscus only when the meniscal body enthesis entity is preserved. Repair of peripheral longitudinal tears will heal and probably preserve the load distribution function of the meniscus, whereas radial tears through the whole meniscal periphery or more central and complex tears may be induced to heal, but probably do not preserve the load distribution function. There is no proof that replacement of the meniscus with an allograft can reestablish some of the important meniscal functions, and thereby prevent or reduce the development of osteoarthrosis which is common after meniscectomy. After implantation, major problems are the remodelling of the graft to inferior structural, biochemical and mechanical properties and its insufficient fixation to bone which fails to duplicate a normal anatomical configuration and therefore a functional meniscal enthesis.     

Releasing the circumferential fixation of the medial meniscus does not affect its kinematics

BackgroundMeniscal functioning depends on the fixation between the meniscal horns and the surrounding tissues. It is unknown, however, whether the integration between the outer circumference of the medial meniscus and the knee capsule/medial collateral ligament also influences the biomechanical behavior of the meniscus. Therefore, we aimed to determine whether detaching and resuturing the circumferential fixation of the medial meniscus influence its kinematic pattern.MethodsHuman cadaveric knee joints were flexed (0°–30°–60°–90°) in a knee loading rig, in neutral orientation and under internal and external tibial torques. Roentgen stereophotogrammetric analysis was used to determine the motion of the meniscus in anteroposterior (AP) and mediolateral (ML) directions. Three fixation conditions were evaluated: (I) intact, (II) detached and (III) resutured.ResultsDetaching and resuturing the circumferential fixation did not alter the meniscal motion pattern in either the AP or ML direction. Applying an additional internal tibial torque caused the medial meniscus to move slightly anteriorly, and an external torque caused a little posterior translation with respect to the neutral situation. These patterns did not change when the circumferential fixation condition was altered.ConclusionsThis study demonstrated that the motion pattern of the medial meniscus is independent of its fixation to the knee capsule and medial collateral ligament.Clinical relevanceThe outcomes of this study can be deployed to design the fixation strategy of a permanent meniscus prosthesis. As peripheral fixation is a complicated step during meniscal replacement, the surgical procedure is considerably simplified when non-resorbable implants do not require circumferential fixation.     

Meniscal lesions in knee joints of broiler fowls

Post-mortem examination of the knee joints of 28 broiler type fowls revealed abnormalities in one or both medial menisci. Certain abnormalities appeared to be associated with knee ligament disruption. These included torn or frayed menisci and those which were displaced, usually in a mesial direction. Histopathological studies revealed that each of these abnormalities was normally associated with degenerative meniscal lesions. Other meniscal abnormalities showed no association with knee ligament disruption. Such menisci can be regarded as being of aberrant shape and most commonly the medial meniscus was enlarged and "discoid". Discoid medial menisci frequently showed histological abnormalities. As in other species, it is suggested that discoid menisci are predisposed to injury probably because of their larger contact area.     

Regional and Zonal Histo‐Morphological Characteristics of the Lapine Menisci

The menisci have crucial weight‐bearing roles in the knee. Regional variations in structure and cellularity of the meniscus have only been minimally investigated. Therefore, the goal of this study was to illustrate the regional cell density, tissue area, and structure of healthy lapine menisci. Skeletally mature Flemish Giant rabbits were used for this study. Upon sacrifice, menisci were removed, fixed in formalin, and cryosectioned. Histological analysis was performed for the detection of sulfated glycosaminoglycans (GAG), collagen Types I and II, cellular density, and tissue area. ANOVA and paired t tests were used for testing of statistical significance. Glycosaminoglycan coverage of the medial meniscus significantly varied between regions, with the anterior region demonstrating significantly more GAG coverage than the posterior region. Inter‐ and intra‐meniscal comparisons revealed variations between zones, with trends that outer zones of the medial menisci had less GAG coverage. Collagen Types I and II had marked characteristics and varying degrees of coverage across regions. Tissue area varied between regions for both medial and lateral menisci. Cellular density was dependent on region in the lateral meniscus. This is the first study to illustrate regional and zonal variation in glycosaminoglycan coverage, size, and cellular density for healthy lapine meniscal tissue. This data provides baseline information for future investigations in meniscal injury models in rabbits. Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.     

The structural and compositional transition of the meniscal roots into the fibrocartilage of the menisci

The meniscal roots, or insertional ligaments, firmly attach the menisci to tibial plateau. These strong attachments anchor the menisci and allow for the generation of hoop stress in the tissue. The meniscal roots have a ligament-like structure that transitions into the fibrocartilagenous structure of the meniscal body. The purpose of this study was to carry out a complete analysis of the structure and tissue organization from the body of the meniscus through the transition region and into the insertional roots. Serial sections were obtained from the meniscal roots into the meniscal body in fixed juvenile bovine menisci. Sections were stained for collagen and proteoglycans (PG) using fast green and safranin-o staining protocols. Unstained sections were imaged used a backlit stereo microscope. Optical projection tomography (OPT) was employed to evaluate the three-dimensional collagen architecture of the root–meniscus transition in lapine menisci. Tie-fibres were observed in the sections of the ligaments furthest from the bovine meniscal body. Blood vessels were observed to be surrounded by these tie-fibres and a PG-rich region within the ligaments. Near the tibial insertion, the roots contained large ligament-like collagen fascicles. In sections approaching the meniscus, there was an increase in tie-fibre size and density. Small tie-fibres extended into the ligament from the epiligamentous structure in the outermost sections of the meniscal roots, while large tie-fibre bundles were apparent at the meniscus transition. The staining pattern indicates that the root may continue into the outer portion of the meniscus where it then blends with the more fibrocartilage-like inner portions of the tissue. In unstained sections it was observed that the femoral side of the epiligamentous structure surrounding the root becomes more fibrous and thickens in the inferior inner portion of the posterior medial root. This thickening changes the shape of the root to more closely resemble the meniscus wedge shape. These observations support the concept of root continuity with the outer portion of the meniscus, thereby connecting with the hoop-like structure of the peripheral meniscus. OPT identified continuous collagen organization from the root into the meniscal body in longitudinal sections. In the radial direction, the morphology of the root continues into the meniscal body consistent with the serially sectioned bovine menisci. Blood vessels were prevalent on the periphery of the root. These blood vessels then arborized to cover the anterior femoral surface of the meniscus. This is the first study of the structural transition between the insertional ligaments (roots) and the fibrocartilagenous body of the menisci. These new structural details are important to understanding the meniscal load-bearing mechanism in the knee.     

3D geometry analysis of the medial meniscus – a statistical shape modeling approach

The geometry‐dependent functioning of the meniscus indicates that detailed knowledge on 3D meniscus geometry and its inter‐subject variation is essential to design well functioning anatomically shaped meniscus replacements. Therefore, the aim of this study was to quantify 3D meniscus geometry and to determine whether variation in medial meniscus geometry is size‐ or shape‐driven. Also we performed a cluster analysis to identify distinct morphological groups of medial menisci and assessed whether meniscal geometry is gender‐dependent. A statistical shape model was created, containing the meniscus geometries of 35 subjects (20 females, 15 males) that were obtained from MR images. A principal component analysis was performed to determine the most important modes of geometry variation and the characteristic changes per principal component were evaluated. Each meniscus from the original dataset was then reconstructed as a linear combination of principal components. This allowed the comparison of male and female menisci, and a cluster analysis to determine distinct morphological meniscus groups. Of the variation in medial meniscus geometry, 53.8% was found to be due to primarily size‐related differences and 29.6% due to shape differences. Shape changes were most prominent in the cross‐sectional plane, rather than in the transverse plane. Significant differences between male and female menisci were only found for principal component 1, which predominantly reflected size differences. The cluster analysis resulted in four clusters, yet these clusters represented two statistically different meniscal shapes, as differences between cluster 1, 2 and 4 were only present for principal component 1. This study illustrates that differences in meniscal geometry cannot be explained by scaling only, but that different meniscal shapes can be distinguished. Functional analysis, e.g. through finite element modeling, is required to assess whether these distinct shapes actually influence the biomechanical performance of the meniscus.     

Role of the anterior intermeniscal ligament in tibiofemoral contact mechanics during axial joint loading

The anterior intermeniscal ligament (AIML) is an anatomically distinct structure that connects the anterior horns of the medial and lateral menisci. We hypothesized that both menisci work together as a unit in converting axial joint loading into circumferential hoop stresses, due to intermeniscal attachments. Therefore, loss of the AIML could lead to increased tibiofemoral contact stress and predispose to arthritic change. In this cadaveric study, we compared tibiofemoral contact pressures on axial loading, before and after sectioning of the AIML. Five fresh frozen human cadaveric knees were mounted on a linear x-y motion table and loaded in extension under axial compression of 1800N (about 2.5 times body weight for a 70kg individual), using a materials testing machine. Tibiofemoral contact pressures before and after sectioning of the AIML were measured using resistive pressure sensors. Contrary to our hypothesis, sectioning of the AIML produced no statistically significant increase in mean contact pressure, peak contact pressure or change in contact area, in either the medial or lateral compartment of the knees. This implies that the menisci work independently in converting axial loads into circumferential hoop stresses, and is probably due to their individual root attachments to the tibia. Based on this study, inadvertent sectioning of the AIML during knee surgery, e.g., arthroscopy, anterograde tibia nailing, anterior cruciate ligament reconstruction, meniscus transplantation and unicondylar knee replacement, is functionally insignificant.     

Expanded human meniscus-derived cells in 3-D polymer-hyaluronan scaffolds for meniscus repair

Treatment options for lesions of the avascular region of the meniscus using regenerative medicine approaches based on resorbable scaffolds are rare. Recent approaches using scaffold-based techniques for tissue regeneration known from cartilage repair may be a promising treatment option for meniscal tears. The aim of the study was the investigation of meniscus matrix formation of in vitro expanded human meniscus-derived cells in a three-dimensional (3-D) bioresorbable polymer graft for meniscal repair approaches. Cultivation of the human meniscus cells was performed in a resorbable scaffold material made of polyglycolic acid (PGA) and hyaluronic acid, stabilized with fibrin glue. Cell viability and distribution of human meniscus cells in PGA-hyaluronan scaffolds were evaluated by fluorescein diacetate and propidium iodide staining. Verification of typical meniscal extracellular matrix molecules like type I and type III collagen was performed histologically, immunohistochemically and by gene expression analysis. In results, 3-D scaffold-based meniscus cultures showed high cell viability over an observational period of 21 days in PGA-hyaluronan scaffolds. On the protein level, type I collagen and proteoglycans were evident. Gene expression analysis confirmed the re-expression of meniscus-specific markers in PGA-hyaluronan scaffolds. This study demonstrated that in vitro expanded human meniscus cells allow for formation of meniscal matrix components when cultured in 3-D PGA-hyaluronan scaffolds stabilized with fibrin. These results encourage scaffold-based approaches for the treatment of meniscal lesions.     

Tie‐fibre structure and organization in the knee menisci

The collagenous structure of the knee menisci is integral to the mechanical integrity of the tissue and the knee joint. The tie‐fibre structure of the tissue has largely been neglected, despite previous studies demonstrating its correlation with radial stiffness. This study has evaluated the structure of the tie‐fibres of bovine menisci using 2D and 3D microscopy techniques. Standard collagen and proteoglycan (PG) staining and 2D light microscopy techniques were conducted. For the first time, the collagenous structure of the menisci was evaluated using 3D, second harmonic generation (SHG) microscopy. This technique facilitated the imaging of collagen structure in thick sections (50–100 μm). Imaging identified that tie‐fibres of the menisci arborize from the outer margin of the meniscus toward the inner tip. This arborization is associated with the structural arrangement of the circumferential fibres. SHG microscopy has definitively demonstrated the 3D organization of tie‐fibres in both sheets and bundles. The hierarchy of the structure is related to the organization of circumferential fascicles. Large tie‐fibre sheets bifurcate into smaller sheets to surround circumferential fascicles of decreasing size. The tie‐fibres emanate from the lamellar layer that appears to surround the entire meniscus. At the tibial and femoral surfaces these tie‐fibre sheets branch perpendicularly into the meniscal body. The relationship between tie‐fibres and blood vessels in the menisci was also observed in this study. Tie‐fibre sheets surround the blood vessels and an associated PG‐rich region. This subunit of the menisci has not previously been described. The size of tie‐fibre sheets surrounding the vessels appeared to be associated with the size of blood vessel. These structural findings have implications in understanding the mechanics of the menisci. Further, refinement of the complex structure of the tie‐fibres is important in understanding the consequences of injury and disease in the menisci. The framework of meniscus architecture also defines benchmarks for the development of tissue‐engineered replacements in the future.     

Clinical significance of meniscal abnormalities on magnetic resonance imaging in an older population

This study examined the prevalence of degenerative changes of knee menisci in aging and evaluated the diagnostic values of magnetic resonance (MR) imaging for assessing meniscal pathology in an older population. Eighty-five knees of asymptomatic volunteers over the age of 40 were scanned using MR imaging. Meniscal abnormalities were graded from 0 to 3 according to intrameniscal MR signals. The subjects were divided into two groups based on the presence or absence of radiographic osteoarthritis. Group I included 43 knees that had normal radiographs and group II consisted of 42 knees that had radiographic evidence of osteoarthritis. Degenerative changes in the menisci involved primarily the posterior segment of the medial meniscus in both groups. Signal changes in the other segments were of a significantly lesser grade than that in the posterior segment of the medial meniscus. The meniscal grade in each segment was significantly higher in group II than in group I. In group I, only two menisci (4.6% ) showed grade 3 signals, even in the posterior portion of the medial meniscus, compared to 21 (50.0%) in group II. Frequency of asymptomatic grade 3 was relatively low even in older subjects if there was no evidence of radiographic osteoarthritic changes. Abnormal MR signals are more likely to have clinical significance, in patients with radiographic changes on plain X-ray.     

构建组织工程化半月板：细胞、支架及生物因子

背景：自体或异体移植修复损伤的半月板治疗效果并不理想,应用组织工程化技术重建半月板的研究成为目前的研究热点。 目的：探讨组织工程化技术修复重建损伤半月板的可行性。 方法：对体外构建组织工程化半月板的种子细胞进行培养,并制备半月板支架材料,将种子细胞依附于支架材料上,利用细胞因子调控种子细胞的黏附、生长、分化和迁移,组织学检查细胞与支架的结合情况以及细胞的数量等。 结果与结论：组织工程化半月板修复研究主要包括种子细胞、支架材料和细胞因子等方面。构建需要的种子细胞有骨髓间充质干细胞和半月板纤维软骨细胞,半月板纤维软骨细胞传至第3代可得出最佳效应浓度。对组织工程化半月板支架材料进行表面修饰,由多材料组成的复合材料具有更好的生物相容性。应用组织工程化技术修复重建损伤的半月板,是今后半月板损伤修复研究一种新的治疗方法。     

Indentation properties and glycosaminoglycan content of human menisci in the deep zone

Menisci are two crescent shaped fibrocartilaginous structures that provide fundamental load distribution and support within the knee joint. Their unique shape transmits axial stresses (i.e. “body force”) into hoop or radial stresses. The menisci are primarily an inhomogeneous aggregate of glycosaminoglycans (GAGs) supporting bulk compression and type I collagen fibrils sustaining tension. It has been shown that the superficial meniscal layers are functionally homogeneous throughout the three distinct regions (anterior, central and posterior) using a 300 μm diameter spherical indenter tip, but the deep zone of the meniscus has yet to be mechanically characterized at this scale. Furthermore, the distribution and content of GAG throughout the human meniscal cross-section have not been examined. This study investigated the mechanical properties, via indentation, of the human deep zone meniscus among three regions of the lateral and medial menisci. The distribution of GAGs through the cross-section was also documented. Results for the deep zone of the meniscus showed the medial posterior region to have a significantly greater instantaneous elastic modulus than the central region. No significant differences in the equilibrium modulus were seen when comparing regions or the hemijoint. Histological results revealed that GAGs are not present until at least ～600 μm from the meniscal surface. Understanding the role and distribution of GAG within the human meniscus in conjunction with the material properties of the meniscus will aid in the design of tissue engineered meniscal replacements.     

The meniscal flounce: a valuable arthroscopic sign

PURPOSE: The purpose of this study was to characterise the incidence and significance of the meniscal flounce. TYPE OF STUDY: Prospective Cohort Study. METHOD: A prospective study of 1088 consecutive knee arthroscopies. RESULTS: Intact menisci tended to have a flounce of characteristic size and position. The presence of this 'normal' flounce was closely correlated with an intact meniscus (p<0.0001). For the medial meniscus with a small flounce in zone 3 the sensitivity, specificity, and positive predictive value (PPV) for an intact medial meniscus were 68.5%; 92.9%; and 92.1% respectively. Conversely the presence of meniscal pathology correlated closely with either an absent or abnormal flounce (p<0.0001). The absence of a medial flounce had sensitivity, specificity, and PPV for a meniscal tear of 82.8%; 84.9%; and 81.9% respectively. CONCLUSIONS: The findings of this study are useful for arthroscopists especially when there is difficulty visualising all of the posterior half of the meniscus. In this situation the presence of a normal flounce is likely to signify an intact meniscus. However the presence of an abnormal or absent flounce may be the sign of an occult meniscal tear requiring better exposure.     

Biomechanical Properties of Transplanted Xenogenic Meniscal Tissue

The clinical repair approaches to meniscal lesions include total or subtotal meniscectomy, transplantation, and tissue engineering. The investigations found that the transplanted xenogenic meniscal tissues, which were treated by60 Co irradiation and deep freezing, maybe one of the effective approaches. In this paper, we evaluated the biomechanical properties of the transplanted xenogenic meniscal tissues at postoperative 1 year. In vitro tensile and compressive tests are performed to compare the properties of tensile elasticity, tensile strength, and compressive elasticcity,between three groups: RAB group of normal rabbit meniscus tissue, Allo group of transplanted allograft meniscal tissue, and Xeno group of transplanted xenogenic meniscal tissue. The meniscus of the Xeno group showed similar tension and compression modulus as the native rabbit meniscus without significant difference(p0.05),and the tension strength of both the Xeno group and the Allo group were less than that of the native rabbit meniscus(0.05p0.1). No significant difference was found between the Xeno group and the Allo group with regard to each biomechanical parameter(p0.05). These base studies will be helpful in future transplantation and tissue engineering efforts.     

组织工程材料修复半月板运动损伤的可行性及特点

背景：组织工程技术的发展为半月板损伤的修复和再造开辟了新的途径,利用该技术构建有功能的半月板在防治半月板切除后的并发症中有重要意义。 目的：综述了组织工程材料在半月板运动损伤修复中的可行性及特点。 方法：由第一作者检索1990/2010 PubMed数据库及中国知网数据库有关天然生物材料、人工合成材料、纳米材料修复半月板损伤的文章。英文检索词为“meniscus,sports injuries,repair,tissue engineering,material ”,中文检索词为“半月板,运动损伤,修复,组织工程,支架材料”。 结果与结论：由于半月板的血供特点,致使半月板无血运区损伤不具备愈合能力。组织工程技术的发展为半月板损伤的修复和再造开辟了新途径。目前报道较多的修复半月板支架材料主要有天然生物材料、人工合成材料、纳米材料等。组织工程化半月板的研究已取得了阶段性的成果,但对支架材料正处于研发实验阶段,还没确定出一种最理想的材料,因此寻求一种具有良好的细胞相容性,可控制的降解率并具有一定力学强度的支架材料仍是半月板组织工程的研究热点。     

Nanoindentation of the insertional zones of human meniscal attachments into underlying bone

The fibrocartilagenous knee menisci are situated between the femoral condyles and tibia plateau and are primarily anchored to the tibia by means of four attachments at the anterior and posterior horns. Strong fixation of meniscal attachments to the tibial plateau provide resistance to extruding forces of the meniscal body, allowing the menisci to assist in load transmission from the femur to the tibia. Clinically, tears and ruptures of the meniscal attachments and insertion to bone are rare. While it has been suggested that the success of a meniscal replacement is dependent on several factors, one of which is the secure fixation and firm attachment of the replacement to the tibial plateau, little is known about the material properties of meniscal attachments and the transition in material properties from the meniscus to subchondral bone. The objective of this study was to use nanoindentation to investigate the transition from meniscal attachment into underlying subchondral bone through uncalcified and calcified fibrocartilage. Nanoindentation tests were performed on both the anterior and posterior meniscal insertions to measure the instantaneous elastic modulus and elastic modulus at infinite time. The elastic moduli were found to increase in a bi-linear fashion from the external ligamentous attachment to the subchondral bone. The elastic moduli for the anterior attachments were consistently larger than those for the matching posterior attachments at similar indentation locations. These results show that there is a gradient of stiffness from the superficial zones of the insertion close to the ligamentous attachment into the deeper zones of the bone. This information will be useful in the continued development of successful meniscal replacements and understanding of fixation of the replacements to the tibial plateau.