Meniscal Reconstruction Research Articles

Meniscus Reconstruction Through Coculturing Meniscus Cells with Synovium-Derived Stem Cells on Small Intestine Submucosa—A Pilot Study to Engineer Meniscus Tissue Constructs

The purpose of this study was to investigate the feasibility of coculturing meniscus cells (MCs) and synovium-derived stem cells (SDSCs) on small intestine submucosa (SIS) to establish an innovative method to engineer in vitro meniscus constructs. About 0.9 million cells (MCs, prelabeled SDSCs [with Vybrant DiI], and a coculture of MCs and prelabeled SDSCs [50:50]) were mixed with fibrin gel and seeded onto freeze-dried SIS discs (5 mm diameter x 1-2 mm thickness) individually. The tissue constructs were incubated in a serum-free defined medium supplemented with 10 ng/mL transforming growth factor beta-1 and 500 ng/mL insulin-like growth factor I for 1 month. One day after cell seeding, samples for scanning electron microscopy were prepared to evaluate cell attachment on the SIS surface. During incubation, fluorescent microscopy was used to trace cell migration (with 4',6-diamidino-2-phenylindole as a counterstain) on SIS scaffold. The tissue constructs were assessed using histology, immunostaining, biochemical analysis, real-time polymerase chain reaction, and compressive modulus. All three groups of cells attached well on SIS. The coculture with SDSCs yielded MC-based tissue constructs with greater cell survival and differentiation into chondrogenic phenotypes, which exhibited higher glycosaminoglycan, collagen II, and Sox 9 but relatively low collagen I, resulting in the concomitant increase in equilibrium modulus. This pilot study demonstrates the advantages of coculturing MCs with SDSCs on SIS for meniscus tissue engineering and regeneration.

Komplikationen mit arthroskopischen Implantaten in der rekonstruktiven Meniskuschirurgie

All-inside devices have become increasingly popular in reconstructive meniscal surgery since their introduction at the beginning of the 1990s. Although the latest clinical investigations show better results for conventional suture techniques, meniscal devices are an important alternative because of the low risk of neurovascular injury and the easy handling of the instruments. Over the years, many reports on specific complications related to all-inside devices have been published. Especially chondral injuries, implant loosening, device migration and capsular or neural irritations have been described. Furthermore, some authors reported on foreign body reactions and cystic granulomas after the use of meniscal fixation devices. However, there is no evidence for a higher infection rate or for specific infections after the use of intra-articular techniques. Clinical reports on complications along with biomechanical studies on meniscal repair devices have led to the enhancement of all-inside techniques through substantial modifications of established products as well as to the development of new implants. After reviewing the latest literature, the complication rate seems to be decreasing. In many ways, all-inside devices are an interesting alternative to conventional suture techniques. A precise knowledge of their potential complications and the pitfalls during surgery however is crucial to make a risk evaluation in the choice of the right technique for meniscal reconstruction.

The clinical developments of meniscal reconstruction

半月板是膝关节的重要组成部分,它能吸收震荡、增加关节面的接触面积和润滑关节,在传递载荷、稳定关节和防止关节退变等方面起着重要作用.因此,对于半月板损伤或切除后患者,如何重建半月板的功能,是膝关节外科医生面临的问题.本文就目前半月板重建的适应证、禁忌证、注意事项、临床疗效及前景等进行了综述。

Preparation of a polyurethane scaffold for tissue engineering made by a combination of salt leaching and freeze-drying of dioxane

In the past several types of synthetic porous materials have been made as meniscus reconstruction materials. Most of these materials lacked a good combination between suitable mechanical properties and a high interconnectivity. In this work porous scaffolds were made from the polyurethane Estane 5701-F1 by freeze drying of a dioxane and water solution in combination with salt leaching. It was possible to obtain very porous scaffolds with a very high interconnectivity. Porosity, pore size and interconnectivity can be independently adjusted by varying the amount of water, porogen size and the amount of porogen used. The obtained compression moduli of the scaffolds were between 40 kPa and 400 kPa with a variation in porosity between 72 and 87%. These scaffolds are very suitable for the use as meniscus replacement materials.

Arthroscopic meniscus surgery

Surgery on the meniscus of the knee joint is one of the most frequently performed operations. The arthroscopic technique currently represents the general treatment standard and except in a few cases has completely superseded the open approach. Arthroscopy facilitates precise diagnosis and classification of all forms of meniscus lesions. In many cases even today partial resection on irreparably damaged meniscus tissue cannot be avoided. The goal is to preserve as much healthy meniscus tissue as possible. Types of tears amenable to reconstruction always require arthroscopic refixation. Various techniques are possible which have different advantages and disadvantages depending on the site of the lesion. In comparison to conventional techniques, in many cases modern implants and instruments make meniscus reconstruction easier entailing less morbidity. Substitution of lost meniscus tissue is possible with allograft transplantation; good results are possible especially on the lateral meniscus. A novel alternative is arthroscopic implantation of a biodegradable collagen matrix, which replaces partial defects on the medial meniscus. Long-term results of this treatment form must be awaited.

Clinicopathologic Study of Conjunctivochalasis

To clarify the structural features of conjunctivochalasis histopathologically. A biopsy of redundant conjunctiva from the same anatomic location of 44 +/- 7.5 years (mean +/- SD, 50.87 years), underwent conjunctivoplasty (termed tear meniscus reconstruction). In all 44 cases, histologic examination disclosed normal conjunctival epithelium and negligible inflammation and lymphocyte infiltration; 39 patients manifested microscopic lymphangiectasia. Elastica van Gieson staining demonstrated elastic fiber fragmentation and sparsely assembled collagen fibers in all 44 cases. There was no discernible difference between specimens from patients with and without complications including tear-deficient dry eye, meibomian gland dysfunction, and clinically observable lymphangiectasia and/or pinguecula. Based on our histopathologic findings, we hypothesize that mechanical forces between the lower lid and conjunctiva gradually interfered with lymphatic flow. Chronic, prolonged mechanical obstruction of lymphatic flow may result in lymphatic dilation and eventually give rise to clinical conjunctivochalasis.

Presence and mechanism of knee articular cartilage degeneration after meniscal reconstruction in dogs

Objective Partial meniscectomy is the golden standard for treating a bucket-handle tear in the meniscus of the knee, but it inevitably leads to articular cartilage degeneration. Surgical creation of an access channel between the lesion and the vascularized synovial lining is intended to induce ingrowth of repair tissue and thus avoid degeneration of articular cartilage.Design The presence and mechanism of cartilage degeneration were evaluated in 24 canine menisci after a longitudinal lesion and access channel had been created in the avascular part of the meniscus. In 12 menisci the channel was implanted with a porous polymer scaffold, while the remaining 12 were left empty. Evaluation was performed using routine histology and antibodies directed against denatured type II collagen (Col2-3/4M).Results Articular degeneration was apparent in the polymer implant group and the empty channel group. This consisted of fibrillation, loss of chondrocytes and decreased proteoglycan content. Areas of fibrillated cartilage always showed positive labeling with the collagen degradation antibody Col2-3/4M. Collagen degradation was also visible in non-fibrillated areas. The upper zone of the cartilage showed swelling especially in the implant group, with empty cell lacunae and moderate levels of Col2-3/4M antibody labeling.Discussion This reconstruction technique cannot be considered superior to partial meniscectomy. We propose that degradation of the collagen type II network is a result of cartilage fibrillation and vice versa. Copyright 2003 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved.

Long-Term Results Following Combined Medial Meniscal Allograft Transplantation and ACL Reconstruction: Minimum Eight and One-Half Year Follow-up (SS-04)

Long-Term Results Following Combined Medial Meniscal Allograft Transplantation and ACL Reconstruction: Minimum Eight and One-Half Year Follow-up (SS-04)

Tissue ingrowth and degradation of two biodegradable porous polymers with different porosities and pore sizes

Commonly, spontaneous repair of lesions in the avascular zone of the knee meniscus does not occur. By implanting a porous polymer scaffold in a knee meniscus defect, the lesion is connected with the abundantly vascularized knee capsule and healing can be realized. Ingrowth of fibrovascular tissue and thus healing capacity depended on porosity, pore sizes and compression modulus of the implant. To study the lesion healing potential, two series of porous polyurethanes based on 50/50 ε-caprolactone/l-lactide with different porosities and pore sizes were implanted subcutaneously in rats. Also, in vitro degradation of the polymer was evaluated. The porous polymers with the higher porosity, more interconnected macropores, and interconnecting micropores of at least 30μm showed complete ingrowth of tissue before degradation had started. In implants with the lower macro-porosity and micropores of 10–15μm degradation of the polymer occurred before ingrowth was completed. Directly after implantation and later during degradation of the polymer, PMN cells infiltrated the implant. In between these phases the foreign body reaction remained restricted to macrophages and giant cells. We can conclude that both foams seemed not suited for implantation in meniscal reconstruction while either full ingrowth of tissue was not realized before polymer degradation started or the compression modulus was too low. Therefore, foams must be developed with a higher compression modulus and more connections with sufficient diameter between the macropores.

Meniscus reconstruction. Established and innovative methods

After the first description of meniscus repairs in the literature it took nearly a century until they were routinely performed in orthopaedic surgery. The scientific basis for meniscus reconstruction needed to be elaborated, including the study of the anatomy, and for instance the vascularisation and the function of the meniscus. After the first experiences with open repair, several arthroscopic techniques have been developed. It has been shown that several factors could influence the healing rate of meniscus lesions. One of the major factors is knee stability. Meniscus repairs performed in conjunction with reconstruction of the anterior cruciate ligament (ACL) have shown higher healing rates (generally > 75%) than isolated repairs, either in stable (50-75% healing rate) or in unstable knees (< 50% in some studies). The localization of the tear is probably the most important factor influencing the healing rate of meniscus repairs. Peripheral tears which are located in the vascular zone of the meniscus heal better than centrally located tears in the avascular area. Many efforts have been provided to enhance the vascularity in this part of the meniscus. None of the proposed techniques have been proven to be definitively effective, or they are too demanding for routine use. Conventional meniscus suture techniques are time-consuming, technically demanding and necessitate incisions at risk for neurovascular structures. In order to simplify meniscus repair several new implants have been developed. They have different forms and are made of different materials among which some are biodegradable. The first clinical results with these techniques are encouraging. However, some new complications have been described. Their incidence and the fate of intraarticular biodegradable devices still has to be defined, especially in the long-term. The present study describes the actual knowledge of meniscus repair and presents the new techniques. It also shows that several questions concerning meniscus repair still need to be answered, and points out the need for further controlled studies.

Solvent-free fabrication of micro-porous polyurethane amide and polyurethane-urea scaffolds for repair and replacement of the knee-joint meniscus

New porous polyurethane urea and polyurethane amide scaffolds for meniscal reconstruction have been developed in a solvent-free process. As soft segments, copolymers of 50/50 l-lactide/ ε-caprolactone have been used. After terminating the soft segment with diisocyanates, chain extension was performed with adipic acid and water. Reaction between the isocyanate groups and adipic acid or water provides carbon dioxide and results in a porous polymer. Extra hydroxyl-terminated prepolymer was added in order to regulate the amount of carbon dioxide formed in the foaming reaction. Furthermore, salt crystals ranging in size from 150 to 355 μm were added in order to induce macroporosity. The pore size was regulated by addition of surfactant and by the use of ultrasonic waves. The resulting porous polymer scaffolds exhibit good mechanical properties like a high-compression modulus of 150 kPa. Chain extension with adipic acid results in better mechanical properties due to better defined hard segments. This results from the lower nucleophilicity of carboxylic acids compared to water and alcohols. By adjusting the reaction conditions, materials in which macropores are interconnected by micropores can be obtained. On degradation only non-toxic products will be released; importantly, the materials were obtained by a simple, reproducible and solvent-free procedure.

Technical innovation: creation of a peripheral vascularized trough to enhance healing in cryopreserved meniscal allograft reconstruction.

The important functions of the meniscus have been well described. Lack of a meniscus may lead to instability and early osteoarthrosis of the knee. Meniscal transplantation is an option following complete or subtotal meniscectomy in symptomatic patients with correct alignment, and mild to moderate chondrosis with the goal of preventing further degenerative sequelae to the knee. Since the first meniscus allograft implantation was performed 1984, there have been reported several open and arthroscopic techniques. We present our technique of arthroscopically assisted transplantation of a cryopreserved meniscal allograft with special consideration given to the technical details of this procedure. This technique employs creation of a circumferential osseocancellous trough in combination with transosseous tibial tunnel fixation and arthroscopic suture passage to both secure and enhance healing of the meniscal allograft.

The Radiographic Position of Medial and Lateral Meniscal Horns as a Basis for Meniscal Reconstruction

Summary: This investigation attempted to determine the radiographic position of human meniscal horn bony insertion sites. This information would prove vital for anatomically correct osseous tunnel placement necessary for the restoration of a functional meniscus after reconstructive surgery. The native bony insertion sites of the medial and lateral meniscus in 13 fresh-frozen human cadaver knees were radiographically examined. After insertion site outline with 22-gauge fine wire, anteroposterior and lateral radiographs were obtained. Radiographic landmarks were then described in detail. Each meniscal horn was found to have a distinct bony insertion site with characteristic and consistent radiographic landmarks defining its margins. Using an arthroscopic guide, 3/32-inch fine wires were drilled into the center of the lateral (5 specimens) and medial (5 specimens) meniscal horns to validate these locations and to establish the clinical usefulness of these measures. Improved understanding of meniscal horn insertion site locations should improve osseous tunnel placements during meniscal transplantation. In the presence of a properly sized allograft, anatomically correct tunnel placement increases the liklihood of restoring normal meniscal function.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 15, No 2 (March), 1999: pp 147–154

Meniscus Reconstruction in Partially Removed Meniscus with Reflected Synovio-capsular Flap in Rabbit

Meniscus Reconstruction in Partially Removed Meniscus with Reflected Synovio-capsular Flap in Rabbit

MENISCAL ALLOGRAFT TRANSPLANTATION

Meniscal allograft transplantation remains an investigational procedure. Loss of native meniscal function has been consistently shown to result in the development and progression of degenerative joint disease. Allograft reconstruction is a technically feasible and reproducible procedure in both animals and humans with demonstrated incorporation of the transplanted graft with host tissue. However, the ultimate success or failure of the meniscal reconstruction cannot be judged solely on demonstration of allograft incorporation. Success must be measured by the prevention or deceleration of the progression of degenerative changes in the knee that has undergone meniscectomy or by the additional stability the reconstruction provides to the knee. To date the long-term viability and function of the meniscal allograft transplant remains unknown.

On the role of aminolysis and transesterification in the synthesis of ε-caprolactone and L-lactide based polyurethanes

Polyurethanes based on a 50/50 copoly(L-lactide/epsilon-caprolactone) prepolymer and butanediisocyanate were made. Chain extending a diisocyanate terminated prepolymer with butanediamine was not possible due to the susceptibility of the lactide bond to aminolysis. Chain extension with butanediol resulted in a polymer with poor mechanical properties due to transesterification. When the copolymer prepolymer was chain-extended with an isocyanate terminated block, transesterification with the chain-extender was avoided and the mechanical properties were increased. When the length of the hard segments was increased the mechanical properties increased further. A L-lactide/epsilon-caprolactone based polyurethane with a tensile strength and modulus of respectively 45 MPa and 60 MPa was made. The polymer contained no poly(L-lactide) crystals and was easy to process. Compared to the high molecular weight 50/50 copoly(L-lactide/epsilon-caprolactone) the polyurethane showed better mechanical properties, is expected to have the same adhesive properties and is expected to have a slower degradation rate. These factors makes this polymer excessively useful for in-vivo tissue engineering in for instance meniscal reconstruction material, nerve guide and artificial skin.

A novel method for fabrication of biodegradable scaffolds with high compression moduli.

It has been previously shown that, when used for meniscal reconstruction, porous copoly(L-lactide/epsilon-caprolactone) implants enhanced healing of meniscal lesions owing to their excellent adhesive properties. However, it appeared that the materials had an insufficient compression modulus to accomplish 100% fibrocartilage formation. In addition, to be used for meniscal prosthesis, the compression modulus of the porous materials should be larger than 150 kPa in order to protect the articular cartilage. A technique was developed to prepare stiff porous materials of a high molecular weight 50/50 copoly(L-lactide/epsilon-caprolactone) suitable for fibrocartilage regeneration in meniscal implants and meniscal prosthesis. Porous microspheres (50-250 microm) were agglutinated in the presence of NaCl crystals (250-300 microm). The microspheres were mixed with solid solvent in order to obtain a homogeneous distribution of solvent over the spheres. By changing the amount of solvent and crystals, the density and the compression modulus could be varied over a range of 0.07 g ml(-1) to 0.5 g dl(-1) and 40-1100 kPa, respectively.

Revision Anterior Cruciate Ligament Surgery: Experience From Germany

From 1976 to 1992, reconstruction after failed anterior cruciate ligament repair or reconstruction was done for 87 patients (8%) compared with 1064 primary operations at the authors' institution. Fifty-seven patients had 1 previous reconstruction, 27 patients had 2, and 3 patients had 3 or more previous reconstructions. Fifty-two patients (60%) were satisfied with their results after a mean followup time of 8 years (range, 2-18 years). Lysholm scores after revisions (68 +/- 12) were significantly inferior compared with scores after primary anterior cruciate ligament surgery (83 +/- 14). The authors favor the use of the patellar tendon or quadriceps tendon autograft in revision surgery. Medial meniscus reconstruction is done whenever possible, or the medial meniscus is replaced by autograft tissue. Open or arthroscopic techniques are used, depending on the individual case.

Use of porous polyurethanes for meniscal reconstruction and meniscal prostheses

In the past, porous materials made of an aromatic polyurethane (PU) were successfully used for meniscal reconstruction in dogs. Since aromatic PUs yield very toxic fragments upon degradation, a linear PU was synthesized by curing a poly(ε-caprolactone) and 1,4- trans-cyclohexane diisocyanate based prepolymer with cyclohexanedimethanol. Porous materials of this polymer were also implanted for meniscal reconstruction. The results were comparable with the most successful implant series so far. Additionally, a porous meniscal prosthesis was developed to replace a total meniscus. Due to the very high shear stresses to which the prosthesis would be exposed, the stress hysteresis phenomenon linear PUs are known to exhibit could be of great consequence. Therefore an aliphatic PU network, synthesized by cross-linking poly(ε-caprolactone) and 1,4- trans-cyclohexane diisocyanate with glycerol, was used. Dislocation caused by tearing out of the sutures was found to be a problem because the tear resistance of the material was relatively low. In this study the tearing problem has been partly circumvented by using a complex suturing technique. Meniscal prostheses turned out to induce fibrocartilage upon implantation, and degeneration of articular cartilage was less severe than after meniscectomy.

Meniscal reconstruction: Present and future

Our treatment of meniscal pathology has changed dramatically over the last 30 years. What began with totalmeniscectomy is now ending with meniscal replacement. Basic science investigation of the preservation, healing, and function of meniscal replacement substitutes has shown that meniscal reconstruction is feasible and successful by various limited criteria. Clinical studies seem to suggest that the ideal candidate may be a young individual with early cartilage wear (grade I or II) who is ligamentously stable without articular incongruity. Surgical techniques using fresh-frozen and cryopreserved meniscal allograft have included open and arthroscopically assisted insertion techniques. Anchoring of the meniscal horns has been described using soft tissue, bone plugs or blocks, or a bony bridge connecting the anterior and posterior horns. Attempting to draw conclusions by comparing the results of the few preliminary studies that have been published is exceptionally difficult. Differences in patient selection, concomitant procedures, meniscal substitute selection, surgical technique, graft fixation, rehabilitation, and length of follow-up make this nearly impossible. Standardized methods for patient selection, operative technique, rehabilitation, and length of follow-up need to be determined to further define meniscal replacement techniques. It remains cautiously optimistic that meniscal replacement remains a treatment for the postmeniscectomy knee.