Intra-Articular Injection of Stromal Cell-Derived Factor 1α Promotes Meniscal Healing via Macrophage and Mesenchymal Stem Cell Accumulation in a Rat Meniscal Defect Model.

The stromal-cell-derived factor-1α (SDF-1) is well-known for playing important roles in the regeneration of tissue by enhancing cell migration. However, the effect of SDF-1 in meniscal healing remains unknown. The purpose of this study is to investigate the effects of intra-articular injection of SDF-1 on meniscus healing in a rat meniscal defect model. The intra-articular SDF-1 injection was performed at meniscectomy and one week later. Macroscopic and histological assessments of the reparative meniscus were conducted at one, two and six weeks after meniscectomy in rats. In the macroscopic evaluation, the SDF-1 group showed an increase in the size of the reparative meniscus at six weeks after meniscectomy compared to the phosphate-buffered saline (PBS) injection (no-treatment) group. Histological findings showed that intra-articular injection of SDF-1 enhanced the migration of macrophages to the site of the regenerative meniscus at one and two weeks after meniscectomy. CD68- and CD163-positive cells in the SDF-1 group at one week after meniscectomy were significantly higher than in the no-treatment group. CD163-positive cells in the SDF-1 group at two weeks were significantly higher than in the no-treatment group. At one week after meniscectomy, there were cells expressing mesenchymal-stem-cell-related markers in the SDF-1 group. These results indicate the potential of regenerative healing of the meniscus by SDF-1 injection via macrophage and mesenchymal stem cell accumulation. In the present study, intra-articular administration of SDF-1 contributed to meniscal healing via macrophage, CD90-positive cell and CD105-positive cell accumulation in a rat meniscal defect model. The SDF-1-CXCR4 pathway plays an important role in the meniscal healing process. For potential clinical translation, SDF-1 injection therapy seems to be a promising approach for the biological augmentation in meniscal injury areas to enhance healing capacity.

Normal meniscal dimensions at different patient ages-MRI evaluation.

OBJECTIVE: The purpose of this work is to evaluate the normal meniscal and tibial dimensions in relation to age and gender in different children using conventional MRI sequences. MATERIALS AND METHODS: Morphometric measurements of the menisci were retrospectively performed on knee MRIs of children (< 18 years). All knee MRIs over a 7-year period were collected. Exclusion criteria included: prior knee surgery or diseases involving the knee joint. A total of 186 children were included, 110 boys and 76 girls, with a mean age of 8.2 years (range, 0.3-17.8 years). Menisci and tibial measurement changes with age and gender as well as differences between the medial and lateral menisci were evaluated. RESULTS: The medial menisci measurements increased with age (p value < 0.001). The lateral menisci measurements increased with age (p value < 0.001), except for the coronal meniscal width (p = 0.084). Coronal and sagittal percentage of meniscal coverage of the tibia decreased with age (p < 0.001). Medial menisci have greater sagittal width and anterior horn height than lateral menisci (p value < 0.001). Lateral menisci are larger in their coronal width and height, and sagittal posterior horn height in comparison to medial menisci (p < 0.001). CONCLUSIONS: Menisci increase in all dimensions in correlation with age; except in the coronal meniscal width, which is a useful dimension to diagnose discoid meniscus on MRI, based on this, it would seem that the currently published size criteria, based on adults, could be applicable to children. The tibia has a faster rate dimension increase in correlation with age in comparison to the menisci.

Formation and maturation of the murine meniscus.

Meniscal injuries are commonplace, but current surgical repair procedures do not prevent degenerative joint changes that occur after meniscal injury and often lead to osteoarthritis. Successful tissue regeneration in adults often recapitulates events that occur during embryogenesis, suggesting that understanding the regulatory pathways controlling these early processes may provide clues for developing strategies for tissue repair. While the mouse is now widely used to study joint diseases, detailed knowledge of the basic biology of murine meniscus is not readily available. Here, we examine meniscal morphogenesis in mice from embryonic day 13.5 (E13.5) to 6 months of age using histology, in situ hybridization, and immunohistochemistry. We find that the meniscus is a morphologically distinct structure at E16 when it begins to regionalize. At birth, the meniscus has a distinguishable inner, avascular, round chondrocyte cell region, an outer, vascularized, fibroblast cell region, and a surface superficial zone. Maturation begins at 2 weeks of age when the meniscus expresses type I collagen, type II collagen, type X collagen, and MMP-13 in specific patterns. By 4 weeks of age, small areas of ossification are detected in the anterior meniscal horn, a common feature seen in rodents. Maturation appears complete at 8 weeks of age, when the meniscus resembles the adult structure complete with ossifying tissue that contains bone marrow like areas. Our results provide, the first systematic study of mouse meniscal development and will be a valuable tool for analyzing murine models of knee joint formation and disease. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1683-1689, 2017.

Are applied growth factors able to mimic the positive effects of mesenchymal stem cells on the regeneration of meniscus in the avascular zone?

Meniscal lesions in the avascular zone are still a problem in traumatology. Tissue Engineering approaches with mesenchymal stem cells (MSCs) showed successful regeneration of meniscal defects in the avascular zone. However, in daily clinical practice, a single stage regenerative treatment would be preferable for meniscus injuries. In particular, clinically applicable bioactive substances or isolated growth factors like platelet-rich plasma (PRP) or bone morphogenic protein 7 (BMP7) are in the focus of interest. In this study, the effects of PRP and BMP7 on the regeneration of avascular meniscal defects were evaluated. In vitro analysis showed that PRP secretes multiple growth factors over a period of 8 days. BMP7 enhances the collagen II deposition in an aggregate culture model of MSCs. However applied to meniscal defects PRP or BMP7 in combination with a hyaluronan collagen composite matrix failed to significantly improve meniscus healing in the avascular zone in a rabbit model after 3 months. Further information of the repair mechanism at the defect site is needed to develop special release systems or carriers for the appropriate application of growth factors to support biological augmentation of meniscus regeneration.

Mastication markedly affects mandibular condylar cartilage growth, gene expression, and morphology.

INTRODUCTION: Mandibular growth is believed to be strongly related to mastication. Furthermore, mandibular condylar cartilage is known to be derived from neural crest cells. We examined whether the degree of chewing affects condylar cartilage growth of the mandible. METHODS: Mice were fed diets with varying hardness. Genes specific to neural crest-derived cells were measured by real-time polymerase chain reaction to compare the expression changes between the mandibular and tibia cartilages. The mandibular condylar cartilage was then evaluated histologically, and proliferation was evaluated using proliferating cell nuclear antigen. Immunostaining was conducted for osteopontin, type X collagen, and Musashi1, and real-time polymerase chain reaction was used to assess the expression levels of osteopontin and type X collagen. RESULTS: Markers including P75, Wnt-1, Musashi1, and Nestin were upregulated in the mandibular condylar cartilage as compared with the tibial cartilage. Histologic assessment of the mandibular cartilage showed that the hypertrophic chondrocyte zone was statistically significantly thicker in mice fed a hard diet. Chondrocyte proliferation and Musashi1 expression were lower in mice fed a hard diet. After 4 weeks, numerous osteopontin and type X collagen-positive cells were observed in mice fed a mixed diet. CONCLUSIONS: Mastication affects the balance between differentiation and proliferation in the mandibular condylar cartilage. This phenomenon might be attributed to the presence of neural crest-derived cells.

Immature articular cartilage and subchondral bone covered by menisci are potentially susceptive to mechanical load.

BACKGROUND: The differences of mechanical and histological properties between cartilage covered by menisci and uncovered by menisci may contribute to the osteoarthritis after meniscectomy and these differences are not fully understood. The purpose of this study is to investigate potential differences in the mechanical and histological properties, and in particular the collagen architecture, of the superficial cartilage layer and subchondral bone between regions covered and uncovered by menisci using immature knee. METHODS: Osteochondral plugs were obtained from porcine tibial cartilage that was either covered or uncovered by menisci. Investigation of the thickness, mechanical properties, histology, and water content of the cartilage as well as micro-computed tomography analysis of the subchondral bone was performed to compare these regions. Collagen architecture was also assessed by using scanning electron microscopy. RESULTS: Compared to the cartilage uncovered by menisci, that covered by menisci was thinner and showed a higher deformity to compression loading and higher water content. In the superficial layer of cartilage in the uncovered regions, collagen fibers showed high density, whereas they showed low density in covered regions. Furthermore, subchondral bone architecture varied between the 2 regions, and showed low bone density in covered regions. CONCLUSIONS: Cartilage covered by menisci differed from that uncovered in both its mechanical and histological properties, especially with regards to the density of the superficial collagen layer. These regional differences may be related to local mechanical environment in normal condition and indicate that cartilage covered by menisci is tightly guarded by menisci from extreme mechanical loading. Our results indicate that immature cartilage degeneration and subchondral microfracture may occur easily to extreme direct mechanical loading in covered region after meniscectomy.

Re-growth of an incomplete discoid lateral meniscus after arthroscopic partial resection in an 11 year-old boy: a case report.

BACKGROUND: Discoid lateral meniscus is common in children. Arthroscopic partial resection is indicated in symptomatic cases generally achieving satisfactory results. CASE PRESENTATION: We present a case of an incomplete discoid lateral meniscus of the right knee in an 11 year-old boy, treated with arthroscopic partial resection, which developed a re-growth of the remnant, restoring the pre-operative incomplete discoid shape. To the best of our knowledge this is the first report about re-growth of a discoid meniscus after surgery. Debate still exists regarding the etiology of a discoid meniscus. Some authors proposed it is the persistence of the normal stage during fetal development. However, most other authors believe it is anomalous and arises through variant morphogenesis. The re-growth of the discoid lateral meniscus following surgery in this patient seems to prove this latter theory. The residual growth of the knee involves also the lateral meniscus and that may have contributed to restoring the meniscus to the previous condition. CONCLUSION: This case report demonstrates discoid meniscal re-growth in a child. The growth spurt may have an impact on meniscal regeneration. Re-growth of the discoid lateral meniscus in our patient favors the hypothesis of variant morphogenesis.

High density type I collagen gels for tissue engineering of whole menisci.

This study investigates the potential of high density type I collagen gels as an injectable scaffold for tissue engineering of whole menisci, and compares these results with previous strategies using alginate as an injectable scaffold. Bovine meniscal fibrochondrocytes were mixed with collagen and injected into micro-computed tomography-based molds to create 10 and 20mgml(-1) menisci that were cultured for up to 4weeks and compared with cultured alginate menisci. Contraction, histological, confocal microscopy, biochemical and mechanical analysis were performed to determine tissue development. After 4weeks culture, collagen menisci had preserved their shape and significantly improved their biochemical and mechanical properties. Both 10 and 20mgml(-1) menisci maintained their DNA content while significantly improving the glycosaminoglycan and collagen content, at values significantly higher than the alginate controls. Collagen menisci matched the alginate control in terms of the equilibrium modulus, and developed a 3- to 6-fold higher tensile modulus than alginate by 4weeks. Further fibrochondrocytes were able to reorganize the collagen gels into a more fibrous appearance similar to native menisci.

Digital micromirror device projection printing system for meniscus tissue engineering.

Meniscus degeneration due to age or injury can lead to osteoarthritis. Although promising, current cell-based approaches show limited success. Here we present three-dimensional methacrylated gelatin (GelMA) scaffolds patterned via projection stereolithography to emulate the circumferential alignment of cells in native meniscus tissue. Cultured human avascular zone meniscus cells from normal meniscus were seeded on the scaffolds. Cell viability was monitored, and new tissue formation was assessed by gene expression analysis and histology after 2weeks in serum-free culture with transforming growth factor ß1 (10ngml(-1)). Light, confocal and scanning electron microscopy were used to observe cell-GelMA interactions. Tensile mechanical testing was performed on unseeded, fresh scaffolds and 2-week-old cell-seeded and unseeded scaffolds. 2-week-old cell-GelMA constructs were implanted into surgically created meniscus defects in an explant organ culture model. No cytotoxic effects were observed 3weeks after implantation, and cells grew and aligned to the patterned GelMA strands. Gene expression profiles and histology indicated promotion of a fibrocartilage-like meniscus phenotype, and scaffold integration with repair tissue was observed in the explant model. We show that micropatterned GelMA scaffolds are non-toxic, produce organized cellular alignment, and promote meniscus-like tissue formation. Prefabrication of GelMA scaffolds with architectures mimicking the meniscus collagen bundle organization shows promise for meniscal repair. Furthermore, the technique presented may be scaled up to repair larger defects.

Effect of polyurethane scaffold architecture on ingrowth speed and collagen orientation in a subcutaneous rat pocket model.

Clinically used scaffolds are suboptimal in regenerating the highly oriented meniscus fiber structure in full meniscal defects. The objective of this study was to test whether anisotropic porous scaffolds with channels resulted in a more meniscus like matrix organization compared to isotropic porous scaffolds. Isotropic polyurethane scaffolds were made via standard solvent leaching techniques. Anisotropic porous scaffolds with channels were made via modified thermal induced phase separation. Both scaffold types were analyzed with light microscopy, scanning electron microscopy and computed nano-tomography. Finally, isotropic and anisotropic scaffolds were bilaterally and subcutaneously implanted on the back of 32 Wistar rats for 1, 4, 8 and 24 weeks to assess tissue ingrowth and matrix organization. Isotropic scaffolds had a pore diameter of 35±14.7 µm and a degree of anisotropy of 0.18, while anisotropic scaffolds had a channel diameter of 20±6.0 µm and a degree of anisotropy of 0.39. After implantation full tissue ingrowth was achieved after 8 and 24 weeks for isotropic and anisotropic, respectively. Isotropic scaffolds had a random tissue infiltration with unorganized collagen deposition, whereas anisotropic scaffolds showed tissue infiltration and collagen alignment in the direction of the channels. Anisotropic scaffolds resulted in a matrix organization that resembled the tissue in the vascularized zone of the meniscus, while isotropic scaffolds resembled the tissue in the avascular zone of the meniscus.

Características biométricas de los meniscos en rodillas de individuos Chilenos / Biometric characteristics of knee meniscus in Chilean individuals

Los meniscos son láminas cartilaginosas que contribuyen a ampliar la escasa concavidad de las superficies articulares de la tibia para recibir a los convexos cóndilos femorales. Satisfacen una necesidad funcional, lo que queda demostrado con su reconstitución después de su extirpación total. Con el propósito de aportar datos sobre sus características biométricas, se registraron diámetros anteroposteriores, transversal y de espesor a diversos niveles, para complementar la anatomía de los mismos en nuestra población. Para ello, se realizó un estudio en 20 meniscos, 10 laterales y 10 mediales, extraídos de cadáveres formolizados, de individuos adultos, chilenos, en los Laboratorios de Anatomía de la Universidad de La Frontera, los cuales se prepararon para efectuar las diversas mediciones, efectuando una limpieza de las estructuras fibrosas que están asociadas a estos cartílagos. Los registros fueron realizados con un caliper digital Mitutoyo de precisión 0,05 mm. El menisco lateral tuvo un promedio para la distancia anteroposterior entre las partes más prominentes del margen anterior del cuerno anterior y el posterior del cuerno posterior de 31,7 mm. La abertura meniscal fue de 11,5 mm; la distancia entre los márgenes anterior y posterior de su cuerno anterior fue de 10,9 mm; la de su cuerno posterior fue de 10,9 mm; el espesor periférico de su parte anterior fue de 3,8 mm, de su parte posterior fue de 6,1 mm y a nivel de su parte media fue de 5,9 mm. El menisco medial tuvo un promedio para la distancia anteroposterior entre las zonas más cercanas a la abertura meniscal de sus extremidades de 43,2 mm. La abertura fue de 26,1 mm; la distancia entre los margenes anterior y posterior de su cuerno anterior fue de 9,2 mm; la de su cuerno posterior fue de 13,5 mm; el espesor periférico a nivel de su parte anterior fue de 4,5 mm, de su parte posterior fue de 6,0 mm y a nivel de su parte media fue de 5,5 mm. Los datos aportados complementarán la anatomía ...

The menisci are cartilage plates that help to expand low concavity of articular surfaces of the tibia to receive the convex femoral condyles. They satisfy functional needs, as has been demonstrated with reconstitution following total excision. In order to provide biometric data on its characteristics, anteroposterior diameters, transverse and thickness at various levels were recorded to complement anatomy of the same in our population. We conducted a study in 20 menisci, 10 lateral and 10 medial from adult Chilean cadaver specimens, in the Anatomy Laboratory, Universidad de La Frontera. The samples were prepared to carry out various measurements cleaning the fibrous structures associated with these menisci. Recordings were registered with a Mitutoyo digital caliper with a 0.05 mm accuracy. Lateral meniscus showed an average anteroposterior distance between horns of 31.7 mm, meniscal opening was 11.5 mm, distance between anterior- posterior borders of the anterior horn was 10.9 mm, of the posterior horn 10.9 mm. The peripheral thickness of its anterior part was 3.8 mm, of its posterior part was 6.1 mm and in its middle section 5.9 mm.The medial meniscus had an average anteroposterior distance between anterior an posterior horn of 43.2 mm. Meniscal opening was 26.1 mm, distance between anterior and posterior borders of the anterior horn was 0.2 mm, in its posterior horn 13.5 mm, peripheral thickness in its anterior part was 4.5 mm, its posterior part was 6.0 mm and at the middle section of the meniscus was 5.5 mm. The data provided will complement anatomy of the menisci in Chilean population.

Meniscus tears in children.

Increased athletic participation by the skeletally immature athlete and a heightened suspicion by physicians have contributed to an increase in the incidence of meniscal injuries in children and adolescents. In young patient, meniscal injury could have long-term consequences, so an understanding of recognition and treatment is essential. We review the anatomy and development of the menisci, review classification and diagnosis of meniscal tears, discuss management options and outcomes of treatment, and focus on discoid lateral meniscus and meniscal cysts.

Quantitative magnetic resonance imaging detects changes in meniscal volume in vivo after partial meniscectomy.

BACKGROUND: Quantifying changes in meniscal volume in vivo before and after partial meniscectomy (PM) could help elucidate the mechanisms involved in osteoarthritis development after meniscal injury and its surgical treatment. Purpose/ HYPOTHESIS: To determine whether quantitative magnetic resonance imaging (qMRI) can detect the immediate reduction in meniscal volume created by PM, while ruling out changes in unresected structures. We hypothesized that qMRI would be reliable for determining meniscal volume within the repeated images of unresected menisci. Additionally, we expected no significant difference in volume between the uninjured menisci of the injured knees and the same menisci of the uninjured knees. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 2. METHODS: Ten subjects with meniscal tears were evaluated with 3-T MRI before and after arthroscopic PM. Manual segmentation was used to create models of the menisci and to determine the preoperative and postoperative meniscal volumes for each subject. The responsiveness and reliability of qMRI for determining meniscal volume in vivo were evaluated using these measurements. We expected a decrease in volume of the resected menisci, but not in the uninjured menisci, after surgery. RESULTS: The mean preoperative volume of the injured menisci was significantly greater than the mean postoperative volume (2896 +/- 277 vs 2480 +/- 277 mm(3); P = .000). There was no significant difference between the mean preoperative and postoperative volumes of the uninjured menisci (2687 +/- 256 vs 2694 +/- 256 mm(3); P = 1.000). CONCLUSION: Manual segmentation demonstrated a significant reduction in the volume of the surgically resected menisci after PM, but no significant change in the volume of unresected meniscal tissue, indicating that the manual segmentation method is responsive. CLINICAL RELEVANCE: This approach offers a novel, reliable method to study the relationship between the volume of meniscal tissue removed during PM and subsequent patient outcomes during long-term clinical studies.

The effects of anterior cruciate ligament lesion on the articular cartilage of growing goats.

Treatment of anterior cruciate ligament (ACL) injury in skeletally immature patients is controversial. The growth plate could be damaged if treated with the reconstruction techniques used to treat instability in adults. For this reason, many authors postpone surgical treatment until skeletal maturity, but the acceptable length of time that treatment can be postponed without causing irreversible damage to the articular cartilage in children with ACL injury is unknown. Until now, no studies have described the pathological findings and the evolution of the lesions of the articular cartilage during the growing period. For this reason, an experimental study on 16 6-month-old, skeletally immature goats was performed. A complete ACL lesion was achieved by removing the ligament. Two animals per group were sacrificed at intervals of 1, 3, 6, and 9 months postoperatively, and macroscopic and microscopic evaluations were performed. The presence of meniscal injury and articular cartilage lesions with progressive aspects were histologically underlined. The hystological observations showed that the complete ACL lesion causes irreversible articular cartilage alterations in growing goats 3 months after injury. These experimental data suggest that ACL reconstruction in growing patients with ACL injury and instability should be indicated without waiting until skeletal maturity.

Col2a1 lineage tracing reveals that the meniscus of the knee joint has a complex cellular origin.

The knee joint consists of multiple interacting tissues that are prone to injury- and disease-related degeneration. Although much is known about the structure and function of the knee's constituent tissues, relatively little is known about their cellular origin and the mechanisms governing their segregation. To investigate the origin and segregation of knee tissues in vivo we performed lineage tracing using a Col2a1-Cre/R26R mouse model system and compared the data obtained with actual Col2a1 expression. These studies demonstrated that at E13.5 the interzone at the presumptive joint site forms when cells within the Col2a1-expressing anlagen cease expression of Col2a1 and not through cellular invasion into the anlagen. Later in development these interzone cells form the cruciate ligament and inner medial meniscus of the knee. At E14.5, after interzone formation, cells that had never expressed Col2a1 appeared in the joint and formed the lateral meniscus. Furthermore, cells with a Col2a1-positive expression history combined with the negative cells to form the medial meniscus. The invading cells started to express Col2a1 1 week after birth, resulting in all cells within the meniscus synthesizing collagen II. These findings support a model of knee development in which cells present in the original anlagen combine with invading cells in the formation of this complex joint.

Three-dimensional culture of human meniscal cells: extracellular matrix and proteoglycan production.

BACKGROUND: The meniscus is a complex tissue whose cell biology has only recently begun to be explored. Published models rely upon initial culture in the presence of added growth factors. The aim of this study was to test a three-dimensional (3D) collagen sponge microenvironment (without added growth factors) for its ability to provide a microenvironment supportive for meniscal cell extracellular matrix (ECM) production, and to test the responsiveness of cells cultured in this manner to transforming growth factor-beta (TGF-beta). METHODS: Experimental studies were approved prospectively by the authors' Human Subjects Institutional Review Board. Human meniscal cells were isolated from surgical specimens, established in monolayer culture, seeded into a 3D scaffold, and cell morphology and extracellular matrix components (ECM) evaluated either under control condition or with addition of TGF-beta. Outcome variables were evaluation of cultured cell morphology, quantitative measurement of total sulfated proteoglycan production, and immunohistochemical study of the ECM components chondroitin sulfate, keratan sulfate, and types I and II collagen. RESULT AND CONCLUSION: Meniscal cells attached well within the 3D microenvironment and expanded with culture time. The 3D microenvironment was permissive for production of chondroitin sulfate, types I and II collagen, and to a lesser degree keratan sulfate. This microenvironment was also permissive for growth factor responsiveness, as indicated by a significant increase in proteoglycan production when cells were exposed to TGF-beta (2.48 microg/ml +/- 1.00, mean +/- S.D., vs control levels of 1.58 +/- 0.79, p < 0.0001). Knowledge of how culture microenvironments influence meniscal cell ECM production is important; the collagen sponge culture methodology provides a useful in vitro tool for study of meniscal cell biology.

Diagnosis of the "large medial meniscus" of the knee on MR imaging.

Although several quantitative magnetic resonance (MR) diagnostic criteria for discoid lateral meniscus (DLM) have been described, there are no criteria by which to estimate the size of the medial meniscus. We define a medial meniscus that exceeds the normal size as a "large medial meniscus" (LMM), and the purpose of this study is to establish the quantitative MR diagnostic criteria for LMM. The MR imaging findings of 96 knees with arthroscopically confirmed intact semilunar lateral meniscus (SLM), 18 knees with intact DLM, 105 knees with intact semilunar medial meniscus (SMM) and 4 knees with torn LMM were analyzed. The following three quantitative parameters were measured: (a) meniscal width (MW): the minimum MW on the coronal slice; (b) ratio of the meniscus to the tibia (RMT): the ratio of minimum MW to maximum tibial width on the coronal slice; (c) continuity of the anterior and posterior horns (CAPH): the number of consecutive 5-mm-thick sagittal slices showing continuity between the anterior horn and the posterior horn of the meniscus on sagittal slices. Using logistic discriminant analysis between intact SLM and DLM groups and using descriptive statistics of intact SLM and SMM groups, the cutoff values used to discriminate LMM from SMM were calculated by MW and RMT. Moreover, the efficacy of these cutoff values and three slices of the cutoff values for CAPH were estimated in the medial meniscus group. "MW> or =11 mm" and "RMT> or =15%" were determined to be effective diagnostic criteria for LMM, while three of four cases in the torn LMM group were true positives and specificity was 99% in both criteria. When "CAPH> or =3 slices" was used as a criterion, three of four torn LMM cases were true positives and specificity was 93%.

Polyurethane scaffolds for meniscal tissue regeneration.

More than 1 million procedures for the total or partial removal of the meniscus in the knee joint are performed in the United States and Europe each year. These meniscectomies lead to degenerative changes of the knee and to immobility of the patients. A polyurethane scaffold is described here, which has been developed as an alternative repair solution.

Comparison of scaffolds and culture conditions for tissue engineering of the knee meniscus.

The menisci of the knee are semilunar fibrocartilaginous structures critical in load bearing, shock absorption, stability, and lubrication. In this study, two commonly used biomaterials, a hydrogel (agarose) and a nonwoven mesh polymer [poly(glycolic acid); PGA], were compared for suitability as scaffold materials for tissue engineering the knee meniscus. In addition, a rotating wall bioreactor culture of both scaffold materials was compared with static cultures. Constructs were cultured for up to 7 weeks in static and rotating wall bioreactor culture. Cell numbers were 22 times higher in PGA than agarose after 7 weeks in culture. Static PGA scaffolds had more than twice the amount of sulfated glycosaminoglycans and three times the amount of collagen compared to static agarose constructs at week 7. The rotating wall bioreactor was not found with increase matrix production or cell proliferation significantly over static cultures.