A Review of Preclinical and Clinical Studies Using Synthetic Materials for Meniscus Replacement

Implantation of autogenous meniscal fragments wrapped with a fascia sheath induces fibrocartilage regeneration in a large meniscal defect in sheep: A histological and biomechanical study

INTRODUCTION

Currently, various studies have been reported to regenerate the meniscus tissue in a large defect after partial meniscectomy using biological or synthetic scaffolds with or without fibrochondrocytes. However, the clinical utility of those treatments has not been established as of yet.

HYPOTHESIS

Purposes of this study were to develop a sheep model to evaluate feasibility of this new surgical strategy to treat the irreparable meniscus injury, and to test the hypothesis that implantation of autogenous meniscal fragments wrapped with a fascia sheath may significantly induce fibrocartilage regeneration in a large meniscal defect in the sheep model.

METHODS AND METHODS

Twenty Suffolk sheep were used. In each animal, an anterior 10-mm width of the right medial meniscus was resected. Then, the animals were divided into the following 2 groups. In Group I, the defect was enveloped with a fascia from the left thigh. In Group II, the resected meniscus fragmented into small pieces was grafted into the defect. Then the defect was enveloped with a fascia. In each group, 5 of 10 sheep were used for histological and biomechanical evaluations, respectively, at 12 weeks after surgery.

RESULTS

In Group I, the defect was incompletely filled with thin fibrous tissues, while fibrocartilage tissues rarely regenerated in the tissue. In Group II, all defects were completely filled with thick fibrocartilage tissues, which were richly stained with the safranin O staining. Both the gross and histological observation score of Group II was significantly (p=0.0005, p=0.0005) greater than that of Group I. Concerning the cross-sectional area of the regenerated tissue, Group II was significantly (p=0.0002) greater than Group I. In the biomechanical evaluation, the maximal load and the linear stiffness of the meniscus-tibia complex were significantly (p=0.0015, p=0.0283) greater in Group II than in Group I.

DISCUSSION

Implantation of autogenous meniscal fragments wrapped with a fascia sheath significantly induces fibrocartilage regeneration into a large meniscal defect in the sheep model.

LEVEL OF EVIDENCE

Not applicable; Controlled Laboratory Study, Experimental in vivo study.

Mechanical Stimulation Increases Knee Meniscus Gene RNA-level Expression in Adipose-derived Stromal Cells

Supplemental Digital Content is available in the text.

Efforts have been made to engineer knee meniscus tissue for injury repair, yet most attempts have been unsuccessful. Creating a cell source that resembles the complex, heterogeneous phenotype of the meniscus cell remains difficult. Stem cell differentiation has been investigated, mainly using bone marrow mesenchymal cells and biochemical means for differentiation, resulting in no solution. Mechanical stimulation has been investigated to an extent with no conclusion. Here, we explore the potential for and effectiveness of mechanical stimulation to induce the meniscal phenotype in adipose-derived stromal cells.

Biomedical-grade, high mannuronic acid content (BioMVM) alginate enhances the proteoglycan production of primary human meniscal fibrochondrocytes in a 3-D microenvironment

Alginates are important hydrogels for meniscus tissue engineering as they support the meniscal fibrochondrocyte phenotype and proteoglycan production, the extracellular matrix (ECM) component chiefly responsible for its viscoelastic properties. Here, we systematically evaluated four biomedical- and two nonbiomedical-grade alginates for their capacity to provide the best three-dimensional (3-D) microenvironment and to support proteoglycan synthesis of encapsulated human meniscal fibrochondrocytes in vitro. Biomedical-grade, high mannuronic acid alginate spheres (BioLVM, BioMVM) were the most uniform in size, indicating an effect of the purity of alginate on the shape of the spheres. Interestingly, the purity of alginates did not affect cell viability. Of note, only fibrochondrocytes encapsulated in BioMVM alginate produced and retained significant amounts of proteoglycans. Following transplantation in an explant culture model, the alginate spheres containing fibrochondrocytes remained in close proximity with the meniscal tissue adjacent to the defect. The results reveal a promising role of BioMVM alginate to enhance the proteoglycan production of primary human meniscal fibrochondrocytes in a 3-D hydrogel microenvironment. These findings have significant implications for cell-based translational studies aiming at restoring lost meniscal tissue in regions containing high amounts of proteoglycans.

Advances and Prospects in Tissue-Engineered Meniscal Scaffolds for Meniscus Regeneration

The meniscus plays a crucial role in maintaining knee joint homoeostasis. Meniscal lesions are relatively common in the knee joint and are typically categorized into various types. However, it is difficult for inner avascular meniscal lesions to self-heal. Untreated meniscal lesions lead to meniscal extrusions in the long-term and gradually trigger the development of knee osteoarthritis (OA). The relationship between meniscal lesions and knee OA is complex. Partial meniscectomy, which is the primary method to treat a meniscal injury, only relieves short-term pain; however, it does not prevent the development of knee OA. Similarly, other current therapeutic strategies have intrinsic limitations in clinical practice. Tissue engineering technology will probably address this challenge by reconstructing a meniscus possessing an integrated configuration with competent biomechanical capacity. This review describes normal structure and biomechanical characteristics of the meniscus, discusses the relationship between meniscal lesions and knee OA, and summarizes the classifications and corresponding treatment strategies for meniscal lesions to understand meniscal regeneration from physiological and pathological perspectives. Last, we present current advances in meniscal scaffolds and provide a number of prospects that will potentially benefit the development of meniscal regeneration methods.

No difference between unicompartmental versus total knee arthroplasty for the management of medial osteoarthtritis of the knee in the same patient: a systematic review and pooling data analysis

INTRODUCTION

One-third of patients with knee osteoarthritis (OA) has involvement of only one compartment, especially the medial one.

SOURCES OF DATA

We performed a comprehensive search of studies comparing unicompartmental knee arthoplasty (UKA) and total knee arthroplasty (TKA) in the same patient on PubMed, OVID/Medline, Cochrane, CINAHL, Google scholar and Embase databases.

AREAS OF AGREEMENT

UKA is indicated in knee with medial OA, no flexion deformity, no joint instability and no varus deformity.

AREAS OF CONTROVERSY

Although high tibial osteotomy, UKA and TKA have been proposed to address medial OA of the knee, the best management is still controversial.

GROWING POINTS

Studies investigating surgical management of medial OA of the knee are increasingly frequent.

AREAS TIMELY FOR DEVELOPING RESEARCH

Large, multicentre, powered, randomized trials comparing UKA and TKA are needed to identify the best management for medial OA of the knee. Moreover, new score systems for satisfaction of the patient should be formulated.