The December 2024 Children’s orthopaedics Roundup. 360. looks at: Establishing best practice for managing idiopathic toe walking in children: a UK consensus; Long-term outcomes of below-elbow casting in paediatric diaphyseal forearm fractures; Residual dysplasia risk persists in developmental dysplasia of the hip patients after Pavlik harness treatment; 3D printing in paediatricorthopaedics: enhancing surgical efficiency and patient outcomes; Pavlik harness treatment for hip dysplasia does not delay motor skill development in children; High prevalence of hip dysplasia found in adolescents with idiopathic scoliosis on routine spine radiographs; Minifragment plates as effective growth modulation for ulnar deformities of the distal radius in children; Long-term success of Chiari pelvic osteotomy in preserving hip function: 30-year follow-up study

INTRODUCTION. Intervertebral disc (IVD) degeneration is not completely understood because of the lack of relevant models. In vivo models are inappropriate because animals are quadrupeds. IVD is composed of the Nucleus Pulposus (NP) and the Annulus Fibrosus (AF), an elastic tissue that surrounds NP. AF consists of concentric lamellae made of collagen I and glycosaminoglycans with fibroblast-like cells located between layers. In this study, we aimed to develop a novel 3D in vitro model of Annulus Fibrosus to study its degeneration. For this purpose, we reproduced the microenvironment of AF cells using 3D printing. METHOD. An ink consisting of dense collagen (30 mg.mL. -1. ) and tyramine-functionalized hyaluronic acid (THA) at 7.5 mg.mL. -1. was first designed by modulating pH and [NaCl] in order to inhibit the formation of polyionic complexes between collagen and THA. Then, composite inks were printed in different gelling baths to form collagen hydrogels. Last, THA photocrosslinking using eosin and green light was performed to strengthen hydrogels. Selected 3D printed constructs were then cellularized with fibroblasts. RESULTS. The physicochemical study revealed that collagen/THA solutions (4:1 ratio) used at pH 5 with 200 mM NaCl were homogenous. In addition, collagen fibrils were observed in these solutions. The dense composite collagen/THA inks printed in a 2X PBS bath rapidly gelled and the photo-crosslinking increased the mechanical properties by 2 to reach 25 kPa (Young's modulus). Then, 3D printing parameters were optimized (85 kPa, extrusion, 4.5 mm/s speed and 80% fill-in percentage) to generate flat and anisotropic lamellae observed by polarized light microscopy. For the in vitro study, several anisotropic layers were printed and fibroblasts seeded between them. Cells adhered to layers, spread, proliferate and aligned along the axis of printed layers. CONCLUSION. Taken together, these results show it is possible to reproduce in vitro the main AF's biochemical and physical properties

Introduction. The surgical treatment of critical-sized bone defects with complex three-dimensional (3D) geometries is a challenge for the treating surgeon. Additive manufacturing such as 3D printing enables the production of highly individualized bone implants meeting the shape of the patient's bone defect and including a tunable internal structure. In this study, we showcase the design process for patient-specific implants with critical-sized tibia defects. Methods. Two clinical cases of patients with critical tibia defects (size 63×20×21 mm and 50×24×17 mm) were chosen. Brainlab software was used for segmentation of CT data generating 3D models of the defects. The implant construction involves multiple stages. Initially, the outer shell is precisely defined. Subsequently, the specified volume is populated with internal structures using Voronoi, Gyroid, and NaCl crystal structures. Variation in pore size (1.6 mm and 1.0 mm) was accomplished by adjusting scaffold size and material thickness. Results. An algorithmic design process in Rhino and Grasshopper was successfully applied to generate model implants for the tibia from Ct data. By integrating a precise mesh into an outer shell, a scaffold with controlled porosity was designed. In terms of the internal design, both Voronoi and Gyroid form macroscopically homogeneous properties, while NaCl, exhibits irregularities in density and consequently, in the strength of the structure. Data implied that Voronoi and Gyroid structures adapt more precisely to complex and irregular outer shapes of the implants. Conclusion. In proof-of-principle studies customized tibia implants were successfully generated and printed as model implants based on resin. Further studies will include more patient data sets to refine the workflows and digital tools for a broader spectrum of bone defects. The algorithm-based design might offer a tremendous potential in terms of an automated design process for 3D printed implants which is essential for clinical application

Introduction. Ink engineering can advance 3D-printability for better therapeutics, with optimized proprieties. Herein, we describe a methodology for yielding 3D-printable nanocomposite inks (NC) using low-viscous matrices, via the interaction between the organic and inorganic phases by chemical coupling. Method. Natural photocurable matrices were synthesized: a protein – bovine serum albumin methacrylate (BSAMA), and a polysaccharide – hyaluronic acid methacrylate (HAMA). Bioglass nanoparticles (BGNP) were synthesized and functionalized via aminosilane chemistry. The functionalization of BSAMA, HAMA, and BGNP were quantified via NMR. To arise extrudable inks, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-Hydroxysuccinimide (NHS) chemistry was used to link innate carboxylic groups of BSAMA/HAMA and amine-functionalized BGNP. Different crosslinker and BGNP amounts were tested. Visible light photopolymerization is performed, using lithium phenyl-2,4,6-trimethylbenzoylphosphinate. The NC's rheological, mechanical, and biological behavior was evaluated before 3D extrusion printability. Result. All composite formulations effectively immobilized and homogeneously dispersed the BGNP, turning low-viscous materials (< 1 Pa) into shear-thinning formulations with tunable increased elastic/viscous moduli (50-500 Pa). More pronounced increments were found with increasing EDC/NHS and BGNP concentrations. The resulting inks produce robust and stable scaffolds successfully retrieved after post-print photocrosslinking (1-5 kPa). Bioactivity in simulated body fluid and in vitro assays using adipose-derive stem cells revealed a similar calcium/phosphate ratio to that of hydroxyapatite, and increased viability and metabolic activity. BSAMA and HAMA demonstrated distinct natures not only in printability but also in overall cellular performance and mechanical properties, making these ideal for interfacial tissue engineering. Conclusion. This strategy demonstrated being effective and reproducible to advance nanocomposites for 3D printing using different types of biomaterials. Further, we envision using both inks to produce hierarchical constructs via extrusion printing, better mimicking bone-to-cartilage interfaces. Acknowledgements. FCT grants (DOI:10.54499/2022.04605.CEECIND/CP1720/CT0021), (BI/UI89/10303/2022), (PRT/BD/154735/2023); EU's Horizon 2020 research and innovation programs InterLynk (Nº953169) and SUPRALIFE (Nº101079482) projects; CICECO-Aveiro Institute of Materials projects (DOI:10.54499/UIDB/50011/2020), (DOI:10.54499/UIDP/50011/2020), and (DOI:10.54499/LA/P/0006/2020), financed by FCT/MCTES(PIDDAC)

Aims

For rare cases when a tumour infiltrates into the hip joint, extra-articular resection is required to obtain a safe margin. Endoprosthetic reconstruction following tumour resection can effectively ensure local control and improve postoperative function. However, maximizing bone preservation without compromising surgical margin remains a challenge for surgeons due to the complexity of the procedure. The purpose of the current study was to report clinical outcomes of patients who underwent extra-articular resection of the hip joint using a custom-made osteotomy guide and 3D-printed endoprosthesis.

Aims

The efficacy of saline irrigation for treatment of implant-associated infections is limited in the presence of porous metallic implants. This study evaluated the therapeutic efficacy of antibiotic doped bioceramic (vancomycin/tobramycin-doped polyvinyl alcohol composite (PVA-VAN/TOB-P)) after saline wash in a mouse infection model implanted with titanium cylinders.

Aims

The aims of this study were to determine the success of a reconstruction algorithm used in major acetabular bone loss, and to further define the indications for custom-made implants in major acetabular bone loss.

Aims

Ganz’s studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthes’ disease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach.

Aims

To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time.

Aims

Custom triflange acetabular components (CTACs) play an important role in reconstructive orthopaedic surgery, particularly in revision total hip arthroplasty (rTHA) and pelvic tumour resection procedures. Accurate CTAC positioning is essential to successful surgical outcomes. While prior studies have explored CTAC positioning in rTHA, research focusing on tumour cases and implant flange positioning precision remains limited. Additionally, the impact of intraoperative navigation on positioning accuracy warrants further investigation. This study assesses CTAC positioning accuracy in tumour resection and rTHA cases, focusing on the differences between preoperative planning and postoperative implant positions.

Aims

The objective of this study was to compare the two-year migration and clinical outcomes of a new cementless hydroxyapatite (HA)-coated titanium acetabular shell with its previous version, which shared the same geometrical design but a different manufacturing process for applying the titanium surface.

Aims

Proper preoperative planning benefits fracture reduction, fixation, and stability in tibial plateau fracture surgery. We developed and clinically implemented a novel workflow for 3D surgical planning including patient-specific drilling guides in tibial plateau fracture surgery.

Meniscal injuries affect over 1.5 million people across Europe and the USA annually. Injury greatly reduces knee joint mobility and quality of life and frequently leads to the development of osteoarthritis. Tissue engineered strategies have emerged in response to a lack of viable treatments for meniscal pathologies. However, to date, constructs mimicking the structural and functional organisation of native tissue, whilst promoting deposition of new extracellular matrix, remains a bottleneck in meniscal repair. 3D bioprinting allows for deposition and patterning of biological materials with high spatial resolution. This project aims to develop a biomimetic 3D bioprinted meniscal substitute. Meniscal tissue was characterised to effectively inform the design of biomaterials for bioprinting constructs with appropriate structural and functional properties. Histology, gene expression and mass spectrometry were performed on native tissue to investigate tissue architecture, matrix components, cell populations and protein expression regionally across the meniscus. 3D laser scanning and magnetic resonance imaging were employed to acquire the external geometrical information prior to fabrication of a 3D printed meniscus. Bioink suitability was investigated through regional meniscal cell encapsulation in blended hydrogels, with the incorporation of growth factors and assessed for their suitability through rheology, scanning electron microscopy, histology and gene expression analysis. Meniscal tissue characterisation revealed regional variations in matrix compositions, cellular populations and protein expression. The process of imaging through to 3D printing highlighted the capability of producing a construct that accurately replicated meniscal geometries. Regional meniscal cell encapsulation into hydrogels revealed a recovery in cell phenotype, with the incorporation of growth factors into the bioink's stimulating cellular re-differentiation and improved zonal functionality. Meniscus biofabrication highlights the potential to print patient specific, customisable meniscal implants. Achieving zonally distinct variations in cell and matrix deposition highlights the ability to fabricate a highly complex tissue engineered construct. Acknowledgements: This work was undertaken as part of the UK Research and Innovation (UKRI)-funded CDT in Advanced Biomedical Materials

Tendons and tendon-to-bone entheses don't usually regenerate after injury, and the hierarchical organization of such tissues makes them challenging sites of study for tissue engineers. In this study, we have tried a novel approach using miRNA and a bioactive bioink to stimulate the regeneration of the enthesis. microRNAs (miRNAs) are short, non-coding sequences of RNA that act as post-transcriptional regulators of gene and protein expression [1]. Mimics or inhibitors of specific miRNAs can be used to restore lost functions at the cell level or improve healing at the tissue level [2,3]. We characterized the healing of a rat patellar enthesis and found that miRNA-16-5p was upregulated in the fibrotic portion of the injured tissue 10 days after the injury. Based on the reported interactions of miRNA-16-5p with the TGF-β pathway via targeting of SMAD3, we aimed to explore the effects of miRNA-16-5p mimics on the tenogenic differentiation of adipose-derived stem cells (ASCs) encapsulated in a bioactive bioink [4,5]. Bioinks with different properties are used for the 3D printing of biomimetic constructs. By integrating cells, materials, and bioactive molecules it is possible to tailor the regenerative capacity of the ink to meet the particular requirements of the tissue to engineer [5]. Here we have encapsulated ASCs in a gelatin-methacryloyl (GelMa) bioink that incorporates miR-16-5p mimics and magnetically responsive microfibers (MRFs). When the bioink is crosslinked in the presence of a magnetic field, the MRFs align unidirectionally to create an anisotropic construct with the ability to promote the tenogenic differentiation of the encapsulated ASCs. Additionally, the obtained GelMA hydrogels retained the encapsulated miRNA probes, which permitted the effective 3D transfection of the ASC and therefore, the regulation of gene expression, allowing to investigate the effects of the miR-16-5p mimics on the tenogenic differentiation of the ASCs in a biomimetic scenario

The aim of this study is to print 3D polycaprolactone (PCL) scaffolds at high and low temperature (HT/LT) combined with salt leaching to induced porosity/larger pore size and improve material degradation without compromising cellular activity of printed scaffolds. PCL solutions with sodium chloride (NaCl) particles either directly printed in LT or were casted, dried, and printed in HT followed by washing in deionized water (DI) to leach out the salt. Micro-Computed tomography (Micro-CT) and scanning electron microscope (SEM) were performed for morphological analysis. The effect of the porosity on the mechanical properties and degradation was evaluated by a tensile test and etching with NaOH, respectively. To evaluate cellular responses, human bone marrow-derived mesenchymal stem/stromal cells (hBMSCs) were cultured on the scaffolds and their viability, attachment, morphology, proliferation, and osteogenic differentiation were assessed. Micro-CT and SEM analysis showed that porosity induced by the salt leaching increased with increasing the salt content in HT, however no change was observed in LT. Structure thickness reduced with elevating NaCl content. Mass loss of scaffolds dramatically increased with elevated porosity in HT. Dog bone-shaped specimens with induced porosity exhibited higher ductility and toughness but less strength and stiffness under the tension in HT whereas they showed decrease in all mechanical properties in LT. All scaffolds showed excellent cytocompatibility. Cells were able to attach on the surface of the scaffolds and grow up to 14 days. Microscopy images of the seeded scaffolds showed substantial increase in the formation of extracellular matrix (ECM) network and elongation of the cells. The study demonstrated the ability of combining 3D printing and particulate leaching together to fabricate porous PCL scaffolds. The scaffolds were successfully printed with various salt content without negatively affecting cell responses. Printing porous thermoplastic polymer could be of great importance for temporary biocompatible implants in bone tissue engineering applications

In 2021 the bone grafting market was worth €2.72 billion globally. As allograft bone has a limited supply and risk of disease transmission, the demand for synthetic grafting substitutes (BGS) continues to grow while allograft bone grafts steadily decrease. Synthetic BGS are low in mechanical strength and bioactivity, inspiring the development of novel grafting materials, a traditionally laborious and expensive process. Here a novel BGS derived from sustainably grown coral was evaluated. Coral-derived scaffolds are a natural calcium carbonate bio-ceramic, which induces osteogenesis in bone marrow mesenchymal stem cells (MSCs), the cells responsible for maintaining bone homeostasis and orchestrating fracture repair. By 3D printing MSCs in coral-laden bioinks we utilise high throughput (HT) fabrication and evaluation of osteogenesis, overcoming the limitations of traditional screening methods. MSC and coral-laden GelXA (CELLINK) bioinks were 3D printed in square bottom 96 well plates using a CELLINK BIO X printer with pneumatic adapter Samples were non-destructively monitored during the culture period, evaluating both the sample and the culture media for metabolism (PrestoBlue), cytotoxicity (lactose dehydrogenase (LDH)) and osteogenic differentiation (alkaline phosphatase (ALP)). Endpoint, destructive assays used included qRT-PCR and SEM imaging. The inclusion of coral in the printed bioink was biocompatable with the MSCs, as reflected by maintained metabolism and low LDH release. The inclusion of coral induced osteogenic differentiation in the MSCs as seen by ALP secretion and increased RUNX2, collagen I and osteocalcin transcription. Sustainably grown coral was successfully incorporated into bioinks, reproducibly 3D printed, non-destructively monitored throughout culture and induced osteogenic differentiation in MSCs. This HT fabrication and monitoring workflow offers a faster, less labour-intensive system for the translation of bone substitute materials to clinic. Acknowledgements: This work was co-funded by Enterprise Ireland and Zoan Biomed through Innovation Partnership IP20221024

Orthopaedic soft tissues, such as tendons, ligaments, and articular cartilage, rely on their unique collagen fiber architectures for proper functionality. When these structures are disrupted in disease or fail to regenerate in engineered tissues, the tissues transform into dysfunctional fibrous tissues. Unfortunately, collagen synthesis in regenerating tissues is often slow, and in some cases, collagen fibers do not regenerate naturally after injury, limiting repair options. One of the research focuses of my team is to develop functional fiber replacements that can promote in vivo repair of musculoskeletal tissues throughout the body. In this presentation, I will discuss our recent advancements in electrowriting 3D printing of natural polymers for creating functional fiber replacements. This manufacturing process utilizes electrical signals to control the flow of polymeric materials through an extrusion nozzle, enabling precise deposition of polymeric fibers with sizes that cannot be achieved using conventional extrusion printing methods. Furthermore, it allows for the formation of fiber organizations that surpass the capabilities of conventional electrospinning processes. During the presentation, I will showcase examples of electrowritten microfiber scaffolds using various naturally-derived polymers, such as gelatin (a denatured form of collagen) and silk fibroin. I will discuss the functional properties of silk-based scaffolds and highlight how they exhibit restored β-sheet and α-helix structures [1]. This restoration results in an elastic response of up to 20% deformation and the ability to withstand cyclic loading without plastic deformation. Additionally, I will present our latest results on the compatibility of this technique with patterning cell-laden fiber structures [2]. This novel biofabrication process allows for the printing of biomimetic microscale architectures with high cell viability, and offers a promising approach to understanding how shear and elongation forces influence cell development of hierarchical (collagen) fibers. Acknowledgements: The author would like to thank the Reprint project (OCENW.XS5.161) and the program “Materials Driven Regeneration” (024.003.013) by the Netherlands Organization for Scientific Research for the financial support

Conventional 3D printing by itself is incapable of creating pores on a micro scale within deposited filaments throughout 3D scaffolds. These pores and hence larger surface areas are needed for cells to be adhered, proliferated, and differentiated. The aim of this work was to fabricate 3D polycaprolactone (PCL) scaffolds with internal multiscale porosity by using two different 3D printing techniques (ink/pellet of polymer-salt composite in low/high temperature printing) combined with salt leaching to improve cell adhesion, and cell proliferation besides to change degradation rate of PCL scaffolds:. 1. Non-solvent phase separation integrated 3D printing of polymer-salt inks with various salt content (i.e., low temperature ink-based printing, LT). 2. FDM printing of composite polymer-salt pellets which will be obtained by casting and evaporating of prepared ink (i.e., high temperature composite-pellet-based printing, HT). Further, the two approaches were followed by post salt leaching. Stem cells were able to attach on the surface and grow up to 14 days based on increasing cellular activities

Titanium alloys are one of the most used for orthopaedic implants and the fabrication of them by 3D printing technology is a raising technology, which could effectively resolve existing challenges. Surface modification of Ti surfaces is often necessary to improve biocorrosion resistance, especially in inflammatory conditions. Such modification can be made by coatings based on hydrogels, like alginate (Alg) - a naturally occurring anionic polymer. The properties of the hydrogel can be further enhanced with calcium phosphates like octacalcium phosphate (OCP) as a precursor of biologically formed hydroxyapatite. Formed Alg-OCP matrices have a high potential in wound healing, delivery of bioactive agents etc. but their effect on 3D printed Ti alloys performance was not well known. In this work, Alg-OCP coated 3D printed samples were studied with electrochemical measurements and revealed significant variations of corrosion resistance vs. composition of the coating. The potentiodynamic polarization test showed that the Alg-OCP-coated samples had lower corrosion current density than simple Alg-coated samples. Electrochemical impedance spectroscopy indicated that OCP incorporated hydrogels had also a high value of the Bode modulus and phase angle. Hence Alg-OCP hydrogels could be highly beneficial in protecting 3D printed Ti alloys especially when the host conditions for the implant placement are inflammatory. AcThis work was supported by the European Union Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Actions GA860462 (PREMUROSA). The authors also acknowledge the access to the infrastructure and expertise of the BBCE – Baltic Biomaterials Centre of Excellence (European Union Horizon 2020 programme under GA857287)

3D Printed polyether-ether-ketone (PEEK) has gained widespread use in clinical practice due to its excellent biocompatibility, biomechanical compatibility, and personalization. However, pre-printed PEEK implants are not without their flaws, including bioinert, optimization distortion of 3D printing digital model and prosthetic mismatching. Recent advancements in mechanical processing technology have made it possible to print bone implants with PEEK fused deposition, allowing for the construction of mechanically adaptable implants. In this study, we aimed to synthesize silanized polycitrate (PCS) via thermal polymerization and in situ graft it to PEEK surface to construct an elastomer coating for 3D printed PEEK implants (PEEK-PCS). This incorporation of PCS allows the implant to exhibit adaptive space filling ability and stress dispersal. In vivo and in vitro results, PEEK-PCS exhibited exceptional osseointegration and osteogenesis properties along with macrophage M2 phenotypic polarization, inflammatory factors reducing, promotion of osteogenic differentiation in bone marrow mesenchymal stem cells (BMSCs). Additionally, PEEK-PCS displays good autofluorescence properties in vitro and in vivo, with stable fluorescence for 14 days, suggesting potential bioimaging applications. The study confirms that PEEK in situ grafting with thermo-polymerized PCS elastomers is a viable approach for creating multifunctional (bone defect adaptation, bioimaging, immune regulation, and osseointegration) implants for bone tissue engineering