Cartilage Replacement Research Articles

Fluoroscope-assisted arthroscopic retroarticular drilling for osteochondral lesions of talus with bone grafting – Clinical outcome analysis and review of literature

Objectives: Early stages of osteochondral lesions with or without cystic changes are amenable to revitalization and cartilage restoration. In these cases, we assess the outcome using our standard technique and by eliminating the need for malleolar osteotomy. Materials and Methods: Seven cases of osteochondral lesion of talus were treated with retroarticular drilling under arthroscopy and fluoroscopy assistance. These cases were followed up for a minimum of 6 months (mean 20 ± 12.53 months). The functional outcome was assessed using American Orthopedic Foot and Ankle Score (AOFAS) hindfoot score. Results: The AOFAS increased from 49.28 (±6.7) points to 85 (±9.12) points and was noted to be statistically significant (P < 0.001). 2/7 ankles were lateral sided lesion and had a history of trauma. 6/7 cases had an intact intraoperative cartilage status, whereas one case had Grade C (fissures and fibrillation). However, the location of lesion or the grade of lesion did not influence the results. Conclusion: This treatment modality seems to be a feasible option for early lesions and can be considered before alternative cartilage replacement treatment strategies are employed.

Effects of solute size and tissue composition on molecular and macromolecular diffusivity in human knee cartilage

Articular cartilage is an avascular tissue. Accordingly, diffusivity represents a fundamental transport mechanism for nutrients and other molecular signals regulating its cell metabolism and maintenance of the extracellular matrix. Understanding how solutes spread into articular cartilage is crucial to elucidating its pathologies, and to designing treatments for repair and restoration of its extracellular matrix. As in other connective tissues, diffusivity in articular cartilage may vary depending both its composition and the specific diffusing solute. Hence, this study investigated the roles of solute size and tissue composition on molecular diffusion in knee articular cartilage. FRAP tests were conducted to measure diffusivity of five molecular probes, with size ranging from ~332Da to 70,000Da, in human knee articular cartilage. The measured diffusion coefficients were related to molecular size, as well as water and glycosaminoglycan (GAG) content of femoral and tibial condyle cartilage. Diffusivity was affected by molecular size, with the magnitude of the diffusion coefficients decreasing as the Stokes radius of the probe increased. The values of diffusion coefficients in tibial and femoral samples were not significantly different from one another, despite the fact that tibial samples exhibited significantly higher water content and lower GAG content of the femoral specimens. Water content did not affect diffusivity. In contrast, diffusivities of large molecules were sensitive to GAG content. This study provides new knowledge on the mechanisms of diffusion in articular cartilage. Our findings can be leveraged to further investigate osteoarthritis and to design treatments for cartilage restoration or replacement.

A technique for measuring the frictional torque of articular cartilage and replacement biomaterials

Understanding the tribological behaviour of articular cartilage enables the development of effective replacement biomaterials. This study presents a technique for the investigation of the frictional torque of articular cartilage, for the assessment of replacement biomaterials. A calcium alginate hydrogel was used as the biomaterial for this study. Three different specimen types were examined to include articular cartilage, calcium alginate hydrogel, alone, and in combination with articular cartilage. An axial load, varying from 10 to 100 N, was applied to the specimen and the frictional torque measured whilst an indenter underwent axial rotation from 0° to 2° to 0° for 100 cycles. The resulting frictional torque magnitude was evaluated with a smooth curve fitting function. Linear regression identified a statistically significant relationship between torque magnitude and axial load (p < 0.05) for all specimen variations. From 10 to 100 N of applied load, mean torque magnitude ranged from 0.08±0.010 to 0.11±0.013 N m, 0.08±0.012 to 0.09±0.016 N m and 0.07±0.017 to 0.09±0.020 N m (mean ± standard deviation), for articular cartilage, calcium alginate separately and in combination with articular cartilage, respectively. This study has established a suitable frictional torque testing protocol for potential cartilage replacement biomaterials.

High strength polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel fabricated by Cold-Drawn method for cartilage tissue substitutes

Poly (vinyl alcohol) (PVA) hydrogel has been considered as promising cartilage replacement materials due to its excellent characteristics such as high water content, low frictional behavior and excellent biocompatibility. However, lack of sufficient mechanical properties and cytocompatibility are two key obstacles for PVA hydrogel to be applied as cartilage substitutes. Herein, Polyacrylic acid (PAA) has been introduced into PVA hydrogel to balance these problems. Compared with pure PVA hydrogel, PVA/PAA hydrogel has the equal excellent biocompatibility, and its cell adhesion is significantly improved. In order to further improve the mechanical properties of hydrogels, Cold-Drawn treatment of hydrogels is performed in this paper. Compared to pure 12% PVA hydrogel, 40.8‐fold, 50.8‐fold, and 46.8‐fold increase in tensile strength, tensile modulus, and toughness, respectively, which can be obtained from 12% PVA/PAA Cold-Drawn hydrogel. These biocompatible composite hydrogels have a great application potential as cartilage tissue substitutes.

A Synthetic Hydrogel Composite with the Mechanical Behavior and Durability of Cartilage

AbstractThis article reports the first hydrogel with the strength and modulus of cartilage in both tension and compression, and the first to exhibit cartilage‐equivalent tensile fatigue strength at 100 000 cycles. These properties are achieved by infiltrating a bacterial cellulose (BC) nanofiber network with a poly(vinyl alcohol) (PVA)–poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid sodium salt) (PAMPS) double network hydrogel. The BC provides tensile strength in a manner analogous to collagen in cartilage, while the PAMPS provides a fixed negative charge and osmotic restoring force similar to the role of aggrecan in cartilage. The hydrogel has the same aggregate modulus and permeability as cartilage, resulting in the same time‐dependent deformation under confined compression. The hydrogel is not cytotoxic, has a coefficient of friction 45% lower than cartilage, and is 4.4 times more wear‐resistant than a PVA hydrogel. The properties of this hydrogel make it an excellent candidate material for replacement of damaged cartilage.

Do high-frequency air-bone gaps persist after ossiculoplasty?

ObjectivesConventional reporting of postoperative hearing outcomes utilizes a pure‐tone averaged air‐bone gap (ABG) that is biased toward low frequencies. Consequently, a high‐frequency ABG after otologic surgery may go unnoticed. In this study, we evaluate changes in low‐ and high‐frequency ABG following ossiculoplasty.Study designRetrospective review.Subjects and settingConsecutive series of patients who underwent ossiculoplasty at a single tertiary care center. Patients with pre‐ and postoperative audiograms were included.MethodsLow‐frequency ABG was calculated as the mean ABG at 250, 500, and 1000 Hz. High‐frequency ABG was calculated at 4 kHz. Pre‐ and postoperative ABGs were compared.ResultsThirty‐seven consecutive patients were included. Mean age at surgery was 38 years (range, 7‐77 years). Reconstruction materials included: cartilage (N = 4), hydroxyapatite cement (N = 5), and partial or total ossicular replacement prostheses (N = 20 and N = 8, respectively). Postoperatively, the mean low‐frequency ABG improved by 11.9 ± 15.1 dB (P < .0001) and the mean high‐frequency ABG improved by 5.9 ± 16.0 dB (P = .030). Low‐frequency ABG closure was significantly larger than high‐frequency ABG closure (P = .007). Mean postoperative persistent high‐frequency ABG was 22.0 ± 13.8 dB.ConclusionIn this series, ossiculoplasty improved ABG across all frequencies, but greater improvements were observed at low frequencies when compared to high frequency. Current reporting standards may not identify persistent high‐frequency ABG. Additional study of the mechanisms of high‐frequency sound conduction in reconstructed middle ears is needed to improve high‐frequency hearing outcomes in ossiculoplasty.Level of evidenceLevel 4.

Mechanical and microscopical characterisation of bilayer hydrogels strengthened by TiO2 nanoparticles as a cartilage replacement candidate

Bilayer hydrogels are suggested as a candidate for cartilage replacement due to their similarity to the native cartilage structure. While their water retention in the lubricious layer is an advantage over other counterparts, their mechanical properties have remained under-explored. In this study, indentation, compression and stress relaxation tests were conducted to evaluate mechanical responses of the bilayer hydrogels. Scanning electron microscope was also utilised to visualise the formation of the porous layer with varying TiO2 nanoparticle (NP) loadings. Our results show that an optimum TiO2 NPs concentration, improved elastic modulus and hardness of the bilayer hydrogels threefold. 0.2wt% TiO2 loading in the polyacrylamide/alginate/ acrylic acid hydrogel exhibited the best material stiffness and stress-strain responses. Viscoelastic responses improved for 0.2wt%, 0.4wt% and 0.6wt% NPs loadings compared to the non-reinforced hydrogel. A unique string-like pore on the surface of 0.2wt% NPs sample was observed, and swelling ratio of this sample was at a moderate level (300 %) compared to other concentrations. The NP loaded bilayer hydrogel demonstrated mechanical features similar to those of articular cartilage, hence could be considered as a cartilage replacement candidate.

Novel Hybrid Composites Based on PVA/SeTiO2 Nanoparticles and Natural Hydroxyapatite for Orthopedic Applications: Correlations between Structural, Morphological and Biocompatibility Properties.

The properties of poly(vinyl alcohol) (PVA)-based composites recommend this material as a good candidate for the replacement of damaged cartilage, subchondral bone, meniscus, humeral joint and other orthopedic applications. The manufacturing process can be manipulated to generate the desired biomechanical properties. However, the main shortcomings of PVA hydrogels are related to poor strength and bioactivity. To overcome this situation, reinforcing elements are added to the PVA matrix. The aim of our work was to develop and characterize a novel composition based on PVA reinforced with Se-doped TiO2 nanoparticles and natural hydroxyapatite (HA), for possible orthopedic applications. The PVA/Se-doped TiO2 composites with and without HA were structurally investigated by FTIR and XRD, in order to confirm the incorporation of the inorganic phase in the polymeric structure, and by SEM and XRF, to evidence the ultrastructural details and dispersion of nanoparticles in the PVA matrix. Both the mechanical and structural properties of the composites demonstrated a synergic reinforcing effect of HA and Se-doped TiO2 nanoparticles. Moreover, the tailorable properties of the composites were proved by the viability and differentiation potential of the bone marrow mesenchymal stem cells (BMMSC) to osteogenic, chondrogenic and adipogenic lineages. The novel hybrid PVA composites show suitable structural, mechanical and biological features to be considered as a promising biomaterial for articular cartilage and subchondral bone repair.

Angiogenic Potential of Tissue Engineered Cartilage From Human Mesenchymal Stem Cells Is Modulated by Indian Hedgehog and Serpin E1.

With rising demand for cartilage tissue repair and replacement, the differentiation of mesenchymal stem cells (BMSCs) into cartilage tissue forming cells provides a promising solution. Often, the BMSC-derived cartilage does not remain stable and continues maturing to bone through the process of endochondral ossification in vivo. Similar to the growth plate, invasion of blood vessels is an early hallmark of endochondral ossification and a necessary step for completion of ossification. This invasion originates from preexisting vessels that expand via angiogenesis, induced by secreted factors produced by the cartilage graft. In this study, we aimed to identify factors secreted by chondrogenically differentiated bone marrow-derived human BMSCs to modulate angiogenesis. The secretome of chondrogenic pellets at day 21 of the differentiation program was collected and tested for angiogenic capacity using in vitro endothelial migration and proliferation assays as well as the chick chorioallantoic membrane (CAM) assay. Taken together, these assays confirmed the pro-angiogenic potential of the secretome. Putative secreted angiogenic factors present in this medium were identified by comparative global transcriptome analysis between murine growth plate cartilage, human chondrogenic BMSC pellets and human neonatal articular cartilage. We then verified by PCR eight candidate angiogenesis modulating factors secreted by differentiated BMSCs. Among those, Serpin E1 and Indian Hedgehog (IHH) had a higher level of expression in BMSC-derived cartilage compared to articular chondrocyte derived cartilage. To understand the role of these factors in the pro-angiogenic secretome, we used neutralizing antibodies to functionally block them in the conditioned medium. Here, we observed a 1.4-fold increase of endothelial cell proliferation when blocking IHH and 1.5-fold by Serpin E1 blocking compared to unblocked control conditioned medium. Furthermore, endothelial migration was increased 1.9-fold by Serpin E1 blocking and 2.7-fold by IHH blocking. This suggests that the pro-angiogenic potential of chondrogenically differentiated BMSC secretome could be further augmented through inhibition of specific factors such as IHH and Serpin E1 identified as anti-angiogenic factors.

Nanostructured Materials for Artificial Tissue Replacements.

This paper review current trends in applications of nanomaterials in tissue engineering. Nanomaterials applicable in this area can be divided into two groups: organic and inorganic. Organic nanomaterials are especially used for the preparation of highly porous scaffolds for cell cultivation and are represented by polymeric nanofibers. Inorganic nanomaterials are implemented as they stand or dispersed in matrices promoting their functional properties while preserving high level of biocompatibility. They are used in various forms (e.g., nano- particles, -tubes and -fibers)—and when forming the composites with organic matrices—are able to enhance many resulting properties (biologic, mechanical, electrical and/or antibacterial). For this reason, this contribution points especially to such type of composite nanomaterials. Basic information on classification, properties and application potential of single nanostructures, as well as complex scaffolds suitable for 3D tissues reconstruction is provided. Examples of practical usage of these structures are demonstrated on cartilage, bone, neural, cardiac and skin tissue regeneration and replacements. Nanomaterials open up new ways of treatments in almost all areas of current tissue regeneration, especially in tissue support or cell proliferation and growth. They significantly promote tissue rebuilding by direct replacement of damaged tissues.

MICROENVIRONMENTAL INFLUENCES ON ARTICULAR CHONDROCYTE DIFFERENTIATION

Background:Immature articular cartilage (a.k.a. articular epiphyseal cartilage complex, AECC), serves dual functions as an articulating layer and surface growth plate. The AECC originates from an uninterrupted cartilaginous template during embryogenesis, presumably stemming from the same pool of progenitors, but it is unclear how the articulating layer is maintained throughout life, while the surface growth plate undergoes endochondral ossification.Hypothesis:The function and fate of chondrocytes in the AECC are not predetermined in the embryo, but instead can be influenced during development by biochemical and/or biomechanical stimuli in the cellular microenvironment.Methods:Microenvironments of the articulating layer and surface growth plate were switched in an in vivo goat model. Twelve 3-week-old goats were used. Osteochondral autografts were harvested from medial and lateral condyles and trochlea of the distal femur. Subchondral bone was removed (Figures 1A and 1B). Grafts were inverted and press-fit into select sites, which were full (condyles) or low (trochlea) weightbearing (Figures 1C through 1E). Animals were allowed ambulation and range of motion as tolerated. Two goats each were euthanized at 1, 2, 3, 6, 12, and 24 weeks postoperatively. Distal femurs were harvested and grafts were analyzed with trichrome staining and in situ hybridization for Col10, Col2, and Prg4.Results:All animals survived surgery, ambulated within 24 hours, and none exhibited signs of surgical site infection. Macroscopically, grafts at the trochlea and lateral condyle maintained a more cartilaginous appearance than those at the medial condyle, but all eventually developed an osseous appearance. Histologically, there was healing over time, with early grafts often containing areas of hemorrhage and occasionally necrosis, followed by formation of granulation tissue and subjacent myelofibrosis, with eventual invasion and ossification. At later timepoints, there was better graft incorporation at the articular surface without replacement by fibrosis at the medial condyle (Figure 2). In situ hybridization demonstrated some Prg4 positive cells and a decrease in Col10 expression at the articular surface (Figure 3).Conclusions:The synovial microenvironment may play a protective role against endochondral ossification. Some incorporation of epiphyseal cartilage into articular cartilage occurred at sites subjected to both compressive and shear forces. Data suggest the existence of local cytokines and/or matrix effects on chondrocytes that stimulate different cell functions and fates. A limitation of this study is its observational nature. Further understanding of articular chondrocyte differentiation and identification of key biochemical and/or biomechanical stimuli hold therapeutic promise for articular cartilage regeneration, repair, and replacement.Figure 1A.through 1E. Osteochondral autografts measuring 4.75 x 7 mm harvested from donor (lateral condyle and distal trochlea) and recipient (medial condyle and proximal trochlea) sites at the distal femur (Figure 1A). Separation of subchondral bone from the AECC (Figure 1B). Grafts inverted and inserted at select sites (Figures 1C through 1E). Experimental control with 13 gauge bone biopsies harvested and inserted in original orientation (Figures 1C through 1E).Figure 2.Histology with trichrome staining showing the articular surface of osteochondral autografts transplanted to the medial femoral condyle at 1, 2, 3, 6, 12, and 24 weeks postoperatively.Figure 3. In situ hybridization of Col2, Col10, and Prg4 gene expression of an osteochondral autograft transplanted to the femoral trochlea at 3 weeks postoperatively.

Clinical and morphological features of age-related, posttraumatic and metabolic phenotypes of late stage knee osteoarthritis

Purpose: To verify clinical, functional, and morphological differences among age-related, posttraumatic and metabolic osteoarthritis (OA) phenotypes in patients with advanced gonarthrosis. Methods: The study covered 120 patients with gonarthrosis (Altman R.D., 1991) of III-IV radiological stages (Kellgren and Lawrence, 1957) hospitalized for total knee replacement. Age-related (over 50 years, absence of previous joint injury and metabolic syndrome, normal body mass index), posttraumatic, metabolic, mixed phenotypes (combination of all factors) were identified and studied, taking into account influence of the most common OA risk factors and proposed classifications in scientific literature (G.Musumeci et al., 2015; A.Dell'Isola et al., 2016; G.Herrero-Beaumont et al., 2017). There were 30 people in every group, and the informed consent was obtained. All patients have undergone clinical examination with filling out WOMAC questionnaire, algofunctional Lequesne index for knee OA, Visual Analogue Scale (VAS). To assess the quality of life the questionnaire MOS SF-36 was used. In 10 patients of every group (total n=40), histopathological study of medial tibiofemoral condyle cartilage and areolar synovial membrane of knee joints was performed using histochemical methods, Mankin H.J.(1971) and Krenn V.(2002) scales. Quantitative data were processed statistically. Results: Female predominance was found in all groups, however the largest number of women was found in metabolic (n=26, 86.7%) and mixed (n=26, 86.7%) phenotypes in comparison with age-related OA (n=18, 60%; р=0,019). The average age of patients with age-related phenotype was the highest (72,5[63; 77] years), and significant differences were detected compared with posttraumatic (62,5 [59; 64] years, p=0.001), metabolic (63 [57;68] years, p = 0.010), mixed (60 [56;64] years, p=0.001) OA. Synovitis was revealed significantly more frequently in metabolic OA (n=23, 76.7%) in comparison with age-related phenotype (n=13, 43.3%; р=0.008). The pain level according to VAS corresponded to severe (7-8 points) in all patients and did not have significant differences between the groups. The highest values of WOMAC questionnaire were found in metabolic phenotype (188 [162;207]), the lowest - in posttraumatic OA (129 [100;166], р=0,001). Lequesne index was the lowest in patients with posttraumatic phenotype (15 [14;19]) and the highest in patients with age-related and metabolic OA (20 [18;21], р=0,004; 20 [19;23], р=0,003, respectively). The lowest values of quality of life were in group of patients with metabolic phenotype (Physical Health - 28 [24.3;31.9], Mental Health - 30.9 [26.9;35.9]), the highest - in posttraumatic OA (34,1 [30,5;36,1], р=0,014 and 40,4 [32,9;43,8], р=0,005, respectively). Histopathological study showed that articular cartilage of patients with age-related OA phenotype was characterized by deep erosions, denudation of subchondral bone, hypocellularity, severe decrease of proteoglycans content. In synovial membrane, lipomatosis and severe inflammatory infiltration were found. In posttraumatic OA numerous surface defects, fibrous cartilage replacement, and chondrocyte clustering were revealed in articular cartilage, and fibrosis was detected in synovial membrane. In metabolic phenotype pronounced vascularization, ossification of articular cartilage, synovial hyperplasia, microcirculation disorders and monocyte/macrophage infiltration were observed. Mixed OA was characterized by combination of variable sings. The most severe cartilage damage according to Mankin scale was shown in age-related OA (8.5 [6;10] points). Significant differences were found in comparison with metabolic phenotype (6 [4.5;6.5] points; (р=0,001). High-grade synovitis was detected in patients with age-related and metabolic OA (5 [3;8] and 4 [3;5] points by Krenn scale, respectively). Conclusions: Age-related, posttraumatic and metabolic OA phenotypes in patients with III-IV radiological stages of gonarthrosis are characterized by various clinical and morphological features. In age-related OA phenotype late clinical debut, moderate pain and dysfunction of knee joints, severe degenerative-dystrophic changes in cartilage and synovial membrane were observed. Posttraumatic OA phenotype was characterized by mild clinical and functional disorders, acceptable quality of life of patients, severe cartilage damage, activation of reparative mechanisms, synovial fibrosis. In metabolic OA phenotype female predominance, frequent clinical synovitis, pronounced clinical and functional manifestations, low quality of patients life, cartilage vascularization and ossification, severe synovial microcirculation disorders were found. Mixed OA phenotype was characterized by variable clinical and morphological picture.

Indian hedgehog in craniofacial neural crest cells links to skeletal malocclusion by regulating associated cartilage formation and gene expression.

The frontal craniofacial skeleton derived from neural crest cells is vital for facial structure and masticatory functions. The exact role of Indian hedgehog (Ihh) in facial and masticatory development has not been fully explored. In this study, we generated craniofacial neural crest cells-specific Ihh deletion mice (Wnt1-Cre;Ihhfl/fl ;Tomatofl/+ ) and found the gradual dwarfism without perinatal lethality. Morphological and histological analyses revealed unambiguous craniofacial phenotypes in mutants, where we observed skeletal malocclusion accompanied by markedly hypoplastic nasomaxillary complex and reversed incisor occlusion. Both the replacement of nasal concha cartilage by turbinate bones and the endochondral ossification of nasal septum ethmoid bone were substantially delayed. We also observed hypoplastic mandibles in mutants where the mandibular ramus was unexpectedly the most affected. Both the condylar process and mandibular angle cartilages were distorted. However, dental examination showed no significant changes in teeth and dentition. Finally, a comprehensive RNA sequence analysis utilizing condylar cartilage identified Ihh-associated gene network including several cell cycle genes and 16 genes related to the extracellular matrix, sulfate transporters, transcription factors, receptors, a ciliogenesis factor, and an adhesion molecule. Our data provide direct in vivo evidence that Ihh plays crucial roles in midface and masticatory system formation, likely by activating key genes.

Tough and Low Friction Polyvinyl Alcohol Hydrogels Loaded with Anti-inflammatories for Cartilage Replacement

The development of new materials that mimic cartilage and its function is an unmet need that will allow replacing the damaged parts of the joints, instead of the whole joint. Polyvinyl alcohol (PVA) hydrogels have raised special interest for this application due to their biocompatibility, high swelling capacity and chemical stability. In this work, the effect of post-processing treatments (annealing, high hydrostatic pressure (HHP) and gamma-radiation) on the performance of PVA gels obtained by cast-drying was investigated and, their ability to be used as delivery vehicles of the anti-inflammatories diclofenac or ketorolac was evaluated. HHP damaged the hydrogels, breaking some bonds in the polymeric matrix, and therefore led to poor mechanical and tribological properties. The remaining treatments, in general, improved the performance of the materials, increasing their crystallinity. Annealing at 150 °C generated the best mechanical and tribological results: higher resistance to compressive and tensile loads, lower friction coefficients and ability to support higher loads in sliding movement. This material was loaded with the anti-inflammatories, both without and with vitamin E (Vit.E) or Vit.E + cetalkonium chloride (CKC). Vit.E + CKC helped to control the release of the drugs which occurred in 24 h. The material did not induce irritability or cytotoxicity and, therefore, shows high potential to be used in cartilage replacement with a therapeutic effect in the immediate postoperative period.

The fabrication and characterization of bioengineered ultra-high molecular weight polyethylene-collagen-hap hybrid bone-cartilage patch

A layered hybrid implant was designed and fabricated for the surgical replacement of worn cartilage to meet the complex requirements of biocompatibility and mechanics. The natural hierarchical structure was purposefully mimicked to improve the implant performance and integration. The hybrid was fabricated using three components: processed collagen gel, hydroxyapatite (HAp) powder and ultra-high molecular weight polyethylene (UHMWPE) in bulk and sponge form. The fabrication included hot molding, sacrificial templating, infusion, and freeze-casting stages. The hybrid had a porous transition layer made of porous UHMWPE impregnated with collagen by means of infusion. SEM and FTIR analyses confirmed successful collagen impregnation of porous UHMWPE. The morphology of transition layer was selected and produced to provide the UHMWPE pore size distribution in a range ∼50–150 μm that is favorable for the osseointegration by osteoblast proliferation. Biocompatibility tests were carried out in vitro. The index of red blood cells hemolysis showed 0.6 % after 4 h of co-incubation that proved excellent biocompatibility of the fabricated UHMWPE-Collagen-HAp hybrid.

Comparison of the compressive mechanical properties of auricular and costal cartilage from patients with microtia

Children born with a small or absent ears undergo surgical reconstruction to restore their auricle. Currently, rib (costal) cartilage is used to carve the auricle. However as alternative, tissue engineered and synthetic materials are being developed to restore the auricle shape to overcome donor site morbidity and limited availability of rib cartilage. However, to date there is limited knowledge regarding the mechanical properties of the auricular and costal cartilage to optimise the required compressive properties of the graft. The remnant auricular and costal cartilage from 20 patients undergoing stage-1 microtia surgery was harvested. On the day of surgery, the cartilage was evaluated in compression, with each sample loaded to 300 g at 1 mm/s. ResultsThe costal cartilage was observed to have a significantly higher Young’s Elastic Modulus than auricular cartilage (average costal cartilage 11.43 MPa vs average auricular cartilage 2 MPa, p < 0.0001). The auricular cartilage showed a significantly higher relaxation rate than costal cartilage (average costal cartilage 0.72 MPa10-4 vs average auricular cartilage 1.93 MPa10-4, p < 0.05). The final absolute relaxation was significantly lower for elastic cartilage than costal cartilage (average costal cartilage 3.35 MPa vs average auricular cartilage 0.2 MPa, p < 0.0001). Alloplastic cartilage replacements used as alternatives for reconstruction were also evaluated. Silicone, Gore-Tex and Medpor were observed to have significantly higher Young’s Elastic Modulus than costal and auricular cartilage.Costal cartilage has a higher Young’s Elastic Modulus in compression compared to auricular cartilage. Current synthetic materials used to replace synthetic cartilage do not mimic costal cartilage, which should be addressed in the future.

Multifunctional load-bearing hybrid hydrogel with combined drug release and photothermal conversion functions

The inability of damaged load-bearing cartilage to regenerate and self-repair remains a long-standing challenge in clinical settings. In the past, the use of PVA hydrogels as cartilage replacements has been explored; however, both pristine and annealed PVA are not ideal for load-bearing cartilage applications, and new materials with improved properties are highly desirable. In this work, we developed a novel hybrid hydrogel system consisting of glycerol-modified PVA hydrogel reinforced by a 3D printed PCL-graphene composite scaffold. The composition of the hydrogel within the hybrid material was optimized to achieve high water retention and enhanced stiffness. The hybrid hydrogel formed by reinforcement with a 3D printed PCL-graphene scaffold with optimized architecture demonstrated desirable mechanical properties (stiffness, toughness, and tribological properties) matching those of natural load-bearing cartilage. Our novel hydrogel system has also been designed to provide drug release and on-demand photothermal conversion functions and at the same time offers excellent biocompatibility with low cell adhesion. These promising properties may allow our unique hybrid hydrogel system to be used for potential applications, such as load-bearing cartilage repair/replacement, as well as targeting certain challenging clinical conditions, such as the treatment of severe arthritis.

The Use of Nanomaterials in Tissue Engineering for Cartilage Regeneration; Current Approaches and Future Perspectives.

The repair and regeneration of articular cartilage represent important challenges for orthopedic investigators and surgeons worldwide due to its avascular, aneural structure, cellular arrangement, and dense extracellular structure. Although abundant efforts have been paid to provide tissue-engineered grafts, the use of therapeutically cell-based options for repairing cartilage remains unsolved in the clinic. Merging a clinical perspective with recent progress in nanotechnology can be helpful for developing efficient cartilage replacements. Nanomaterials, < 100 nm structural elements, can control different properties of materials by collecting them at nanometric sizes. The integration of nanomaterials holds promise in developing scaffolds that better simulate the extracellular matrix (ECM) environment of cartilage to enhance the interaction of scaffold with the cells and improve the functionality of the engineered-tissue construct. This technology not only can be used for the healing of focal defects but can also be used for extensive osteoarthritic degenerative alterations in the joint. In this review paper, we will emphasize the recent investigations of articular cartilage repair/regeneration via biomaterials. Also, the application of novel technologies and materials is discussed.

Nanoscale insight into the degradation mechanisms of the cartilage articulating surface preceding OA.

Osteoarthritis (OA) is a degenerative joint disease and a leading cause of disability globally. In OA, the articulating surface of cartilage is compromised by fissures and cracks, and sometimes even worn away completely. Due to its avascular nature, articular cartilage has a poor self-healing ability, and therefore, understanding the mechanisms underlying degradation is key for OA prevention and for optimal design of replacements. In this work, the articulating surface of bovine cartilage was investigated in an environment with enhanced calcium concentration -as often found in cartilage in relation to OA- by combining atomic force microscopy, spectroscopy and an extended surface forces apparatus for the first time. The experimental results reveal that increased calcium concentration irreversibly weakens the cartilage's surface layer, and promotes stiction and high friction. The synergistic effect of calcium on altering the cartilage surface's structural, mechanical and frictional properties is proposed to compromise cartilage integrity at the onset of OA. Furthermore, two mechanisms at the molecular level based on the influence of calcium on lubricin and on the aggregation of the cartilage's matrix, respectively, are identified. The results of this work might not only help prevent OA but also help design better cartilage replacements.

Total knee replacement without patellar resurfacing: about 60 cases

Lors de la mise en place d’une prothèse totale du genou (PTG), une des principales problématiques de la technique chirurgicale est le choix à faire entre la conservation de la patella ou son resurfaçage avec remplacement du cartilage patellaire par une prothèse. Cette problématique continue à faire l’objet d’une controverse au sein de la communauté orthopédique. Il n'y a pas de consensus clair sur la gestion optimale de la rotule pendant arthroplastie totale du genou (PTG). Ce travail est une étude rétrospective concernant 60 arthroplasties totales du genou sans resurfaçage de la rotule, implantées au Service de Chirurgie Traumatologique et Orthopédique (B) du CHU Hassan II de Fès, depuis janvier 2009 à décembre 2015. L’âge moyen de nos patients était de 58 ans avec des extrêmes allant de 20 ans à 80 ans. La prédominance féminine est nette avec 41 femmes soit (72%) et 16 hommes soit (28%). Cliniquement, nos malades se plaignaient de douleurs de type mécanique dans la majorité des cas et tous nos patients ont bénéficié d’un examen clinique et radiologique. Le score IKS a été utilisé pour évaluer l’état du genou avant et après l’intervention. L’acte opératoire a consisté en une arthroplastie totale du genou par prothèse totale du genou sans resurfaçage de la rotule. Les complications post-opératoires étaient marquées par 7 cas de douleur antérieur de genou, 2 cas d’infections cutanées superficielles traitées par une antibiothérapie adéquate et 3 cas de raideur. Aucun cas d’hématome ou de phlébite ou de sepsis n’a été signalé. Les résultats cliniques après un recul de 18 mois ont été satisfaisants. À la lumière de ces résultats, la conservation de la patella a permis d’obtenir des résultats très satisfaisants à moyen terme concernant la douleur et la fonction. De plus, les complications potentielles des prothèses patellaires ont été évitées. Une seule contrainte demeure concernant l’avenir de ces prothèses implantées sans resurfaçage est l’apparition ou parfois la persistance de la douleur antérieur du genou d’où la nécessité d’un resurfaçage secondaire.