Addressing bone defects is a complex medical challenge that involves dealing with various skeletal conditions, including fractures, osteoporosis (OP), bone tumours, and bone infection defects. Despite the availability of multiple conventional treatments for these skeletal conditions, numerous limitations and unresolved issues persist. As a solution, advancements in biomedical materials have recently resulted in novel therapeutic concepts. As an emerging biomaterial for bone defect treatment, graphene oxide (GO) in particular has gained substantial attention from researchers due to its potential applications and prospects. In other words, GO scaffolds have demonstrated remarkable potential for bone defect treatment. Furthermore, GO-loaded biomaterials can promote osteoblast adhesion, proliferation, and differentiation while stimulating bone matrix deposition and formation. Given their favourable biocompatibility and osteoinductive capabilities, these materials offer a novel therapeutic avenue for bone tissue regeneration and repair. This comprehensive review systematically outlines GO scaffolds’ diverse roles and potential applications in bone defect treatment.

Cite this article: Bone Joint Res 2024;13(12):725–740.

Over the last decades, biodegradable metals emerged as promising materials for various biomedical implant applications, aiming to reduce the use of permanent metallic implants and, therefore, to avoid additional surgeries for implant removal. However, among the important issue to be solved is their fast corrosion - too high to match the healing rate of the bone tissue. The most effective way to improve this characteristic is to coat biodegradable metals with substituted calcium phosphates. Tricalcium phosphate (β-TCP) is a resorbable bioceramic widely used as synthetic bone graft. In order to modulate and enhance its biological performance, the substitution of Ca2+ by various metal ions, such as strontium (Sr2+), magnesium (Mg2+), iron (Fe2+) etc., can be carried out. Among them, copper (Cu2+), manganese (Mn2+), zinc (Zn2+) etc. could add antimicrobial properties against implant-related infections. Double substitutions of TCP containing couples of Cu2+/Sr2+ or Mn2+/Sr2+ ions are considered to be the most perspective based on the results of our study. We established that single phase Ca3−2x(MˊMˊˊ)x(PO4)2 solid solutions are formed only at x ≤ 0.286, where Mˊ and Mˊˊ—divalent metal ions, such as Zn2+, Mg2+, Cu2+, Mn2+, and that in case of double substitutions, the incorporation of Sr2+ ions allows one to extend the limit of solid solution due to the enlargement of the unit cell structure. We also reported that antimicrobial properties depend on the substitution ion occupation of Ca2+ crystal sites in the β-TCP structure. The combination of two different ions in the Ca5 position, on one side, and in the Ca1, Ca2, Ca3, and Ca4 positions, on another side, significantly boosts antimicrobial properties. In the present work, zinc-lithium (Zn-Li) biodegradable alloys were coated with double substituted Mn2+/Sr2+ β-TCP and double substituted Cu2+/ Sr2+ β-TCP, with the scope to promote osteoinductive effect (due to the Sr2+ presence) and to impart antimicrobial properties (thanks to Cu2+ or Mn2+ ions). The Pulsed Laser Deposition (PLD) method was applied as the coating's preparation technique. It was shown that films deposited using PLD present good adhesion strength and hardness and are characterized by a nanostructured background with random microparticles on the surface. For coatings characterization, Fourier Transform Infrared Spectroscopy, X-ray Diffraction, and Scanning Electron Microscopy coupled with Energy Dispersive X-ray and X-ray Photoelectron Spectroscopy were applied. The microbiology tests on the prepared coated Zn-Li alloys were performed with the Gram-positive (Staphylococcus aureus, Enterococcus faecalis) and Gram-negative (Salmonella typhimurium, Escherichia coli) bacteria strains and Candida albicans fungus. The antimicrobial activity tests showed that Mn2+/Sr2+ β-TCP -coated and Cu2+/Sr2+ β-TCP coated Zn-Li alloys were able to inhibit the growth of all five microorganisms. The prepared coatings are promising in improving the degradation behavior and biological properties of Zn-Li alloys, and further studies are necessary before a possible clinical translation

Osteoarthritis (OA) is mainly caused by ageing, strain, trauma, and congenital joint abnormalities, resulting in articular cartilage degeneration. During the pathogenesis of OA, the changes in subchondral bone (SB) are not only secondary manifestations of OA, but also an active part of the disease, and are closely associated with the severity of OA. In different stages of OA, there were microstructural changes in SB. Osteocytes, osteoblasts, and osteoclasts in SB are important in the pathogenesis of OA. The signal transduction mechanism in SB is necessary to maintain the balance of a stable phenotype, extracellular matrix (ECM) synthesis, and bone remodelling between articular cartilage and SB. An imbalance in signal transduction can lead to reduced cartilage quality and SB thickening, which leads to the progression of OA. By understanding changes in SB in OA, researchers are exploring drugs that can regulate these changes, which will help to provide new ideas for the treatment of OA.

Cite this article: Bone Joint Res 2023;12(9):536–545.

Aims

Long non-coding RNAs (lncRNAs) act as crucial regulators in osteoporosis (OP). Nonetheless, the effects and potential molecular mechanism of lncRNA PCBP1 Antisense RNA 1 (PCBP1-AS1) on OP remain largely unclear. The aim of this study was to explore the role of lncRNA PCBP1-AS1 in the pathogenesis of OP.

The implantation of endoprosthesis is a routine procedure in orthopaedics. Endoprosthesis are mainly manufactured from ceramics, polymers, metals or metal alloys. To ensure longevity of the implants they should be as biocompatible as possible and ideally have antibacterial properties, to avoid periprosthetic joint infections (PJI). Various antibacterial implant materials have been proposed, but have so far only been used sporadically in patients. PJI is one of the main risk factors for revision surgeries. The aim of the study was to identify novel implant coatings that both exhibit antibacterial properties whilst having optimal biocompatibility. Six different novel implant coatings and surface modifications (EBM TiAl6V4, strontium, TiCuN, TiNbN, gentamicin phosphate (GP), gentamicin phosphate+cationic polymer (GP+CP)) were compared to standard CoCrMo-alloy. The coatings were further characterized with regard to the surface roughness. E. coli and S. capitis were cultured on the modified surfaces to investigate the antibacterial properties. To quantify bacterial proliferation the optical density (OD) was measured and viability was determined using colony forming units (CFU). Murine bone marrow derived macrophages (BMMs) were cultured on the surfaces and differentiated into osteoblasts to quantify the mineralisation using the alizarin red assay. All novel coatings showed reduced bacterial proliferation and viability compared to standard CoCrMo-alloy. A significant reduction was observed for GP and GP+CP coated samples compared to CoCrMo (OD. GP,E.coli. = 0.18±0.4; OD. GP+CP,E.coli. = 0.13±0.3; p≤0.0002; N≥7-8). An increase in osteoblast-mediated mineralisation was observed on all surfaces tested compared to CoCrMo. Furthermore, GP and GP+CP coated samples showed a statistically significant increase (M. GP. = 0.21±0.1; M. GP+CP. = 0.25±0.2; p<0.0001; N≥3-6). The preliminary data indicates that the gentamicin containing surfaces have the most effective antibacterial property and the highest osseointegrative capacity. The use of antibiotic coatings on prostheses could reduce the risk of PJI while being applied on osseointegrative implant surfaces

Minimally invasive surgery for the restoration of bone tissues lost due to diseases and trauma is preferred by the health care system as the related costs are continuously increasing. Recently, efforts have been paid to optimize injectable calcium phosphate (CaP) cements which have been recognized as excellent alloplastic material for osseous augmentation because of their unique combination of osteoconductivity, biocompatibility and mouldability. The sol-gel synthesis approach appears to be the most suitable route towards performing injectable calcium phosphates. Different strategies used to prepare bioactive and osteoinductive injectable CaP are reported. CaP gels complexed with phosphoserine-tethered poly(ε-lysine) dendrons (G3-K PS) designed to interact with the ceramic phase and able to induce osteogenic differentiation of human mesenchymal stem cells (hMSCs) is discussed. Recently, attention has been given to the modification of hydroxyapatite with Strontium (Sr) due to its dual mode of action, simultaneously increasing bone formation (stimulating osteoblast differentiation) while decreasing bone resorption (inhibiting osteoclast differentiation). The effect of systems based on strontium modified hydroxyapatite (Sr-HA) at different composition on proliferation and osteogenic differentiation of hMSC is described. One more approach is based on the use of antimicrobial injectable materials. It has been demonstrated that some imidazolium, pyridinium and quaternary ammonium ionic liquids (IL) have antimicrobial activity against some different clinically significant bacterial and fungal pathogens. Here, we report several systems based on IL at different alkyl-chain length incorporated in Hydroxyapatite (HA) through the sol-gel process to obtain an injectable material with simultaneous opposite responses toward osteoblasts and microbial proliferation

The large bone defects with high risk of delayed bone union and pseudoarthrosis remain significant clinical challenge. Aim of the present study was the investigation of the critical size fracture healing process in transgenic mice using a novel beta-TCP scaffold. The luciferase transgenic mice strains (BALB/C-Tg(NF-kappaB-RE-luc)-Xen) and FVB/N-Tg(Vegfr2-luc)-Xen were used. Critical size fracture on femur was performed and stabilized using external fixation (RISystem). The fracture was bridged with a synthetic scaffold with and without Strontium. In consequence, the expression levels of NF-kappaB and VEGFR2 could be monitored in a longitudinal fashion using the Xenogen imaging system for two months. Animals were euthanized, serial section of femur were prepared, and the fracture sites were histologically examined. Sr reduced inflammation in the early phase of healing (15th days), but it was increased in the late healing stage. The level of VEGFR2 activity increases in the Sr doped beta-TCP group at the 15th day, the luciferase activity starts to decrease in this group and show significantly less activity compared to other groups in the second half. In the group without scaffold a connective tissue formation were observed. In both, beta-TCP and beta-TCP+Sr, the connection of newly formed tissue within integrated canals in scaffold was visible. Tissue formation in beta-TCP+Sr group was significantly higher than in the beta-TCP group, whereas the percentage of osseous tissue in relation to the newly formed tissue was in beta-TCP scaffold much more than in beta-TCP+ Sr groups. This study presents the first data regarding VEGFR2 and NF-kappB and angiogenesis activity profiles during fracture healing. The collected longitudinal data reduces the number of experimental animals in the study. Addition of strontium in scaffolds influenced the inflammation in different stage of the healing. This effect might influence the healing process and may prove to be advantageous for osteoporosis fracture healing

Bone tissue engineering is a promising strategy to treat the huge number of bone fractures caused by progressive population ageing and diseases i.e., osteoporosis. The bioactive and biomimetic materials design modulating cell behaviour can support healthy bone tissue regeneration. In this frame, type I collagen and hydroxyapatite (HA) have been often combined to produce biomimetic scaffolds. In addition, mesoporous bioactive glasses (MBGs) are known for their ability to promote the deposition of HA nanocrystals and their potential to incorporate and release therapeutic ions. Furthermore, the use of 3D printing technologies enables the effective design of scaffolds reproducing the natural bone architecture. This study aims to design biomimetic and bioactive 3D printed scaffolds that mimic healthy bone tissue natural features in terms of chemical composition, topography and biochemical cues. Optimised collagenous hybrid systems will be processed by means of extrusion 3D printing technologies to obtain high resolution bone-like structures. Protocols of human co-cultures of osteoblasts and osteoclasts will be developed and used to test the 3D scaffolds. Type I collagen has been combined with rod-like nano-HA and strontium containing MBGs (micro- and nano-sized particles) in order to obtain hybrid systems resembling the composition of native bone tissue. A comprehensive rheological study has been performed to investigate the potential use of the hybrid systems as biomaterial inks. Mesh-like structures have been obtained by means of extrusion-based technologies exploiting the freeform reversible embedding of suspended hydrogels (FRESH) approach. Different crosslinking methods have been tested to improve final constructs mechanical properties. Both crosslinked and non-crosslinked biomaterials were cultured with human osteoblasts and osteoclasts to assay the hybrid matrix biocompatibility as well as its influence on cell behaviour. Homogeneous hybrid systems have been successfully developed and characterised, proving their suitability as biomaterial inks for 3D printing technologies. Mesh-like structures have been extruded in a thermo-reversible gelatine slurry, exploiting the sol-gel transition of the systems under physiological conditions. Covalent bonds between collagen molecules have been promoted by genipin treatment, leading to a significant increase in matrix strength and stability. The collagen methacrylation and the further UV-crosslinking are under investigation as alternative promising method to reinforce the 3D structure during the printing process. Biological tests showed the potential of the developed systems especially for genipin treated samples, with a significant adhesion of primary cells. Collagenous hybrid systems proved their suitability for bioactive 3D printed structures design for bone tissue engineering. The multiple stimuli provided by the scaffold composition and structure will be investigated on both direct and indirect human osteoblasts and osteoclasts co-culture, according to the developed protocols

Mesoporous bioactive glasses (MBGs) have been widely studied as bone regeneration systems, due to their bioactivity and ability to store and release therapeutic agents with specific biological functions. The incorporation of these nanomaterials into a thermosensitive hydrogel (TSH), in which a solution undergoes a sol-gel transition under physiological conditions, represents a promising approach to design multifunctional devices able to deliver selected molecules to pathological sites. In fact, this system can perfectly fit the defect cavity shape prior to the complete gelation, and acts as a carrier for therapeutic agents prolonged release in situ. This challenging concept is the underlying idea of the MOZART project, whose objective was to develop a library of MBGs containing different therapeutic ions and drugs, to be used as a new, smart platform technology for highly targeted therapies to enhance bone healing. The aim of this work is to investigate the bone regeneration potential of MBGs containing strontium ions (pro-osteogenic) and incorporated into thermosensitive poly(etherurethane)(PEU) based on Poloxamer407. In order to further increase the pro-osteogenic response, MBGs were also loaded with N-acetylcysteine (NAC). MBGs containing 2%mol of Sr. 2+. were prepared by an aerosol-assisted spray-drying method and NAC was loaded post-synthesis via an incipient wetness method. The PEU hydrogel (SHP407) was synthesized via a two-step procedure in nitrogen atmosphere. Particles were characterized (FE-SEM, N. 2. adsorption-desorption analysis, TGA, DSC, FT-IR and XRD) and then incorporated into the hydrogel. The hybrid systems rheological properties and stability in aqueous environment at 37°C, and its ability to co-release Sr. 2+. and NAC were analysed. After preliminary biological in vitro tests, a proof-of-concept rodent study was run to assess the ability of the resulting formulation as bone healing device. X-ray at 2 and 4-weeks post-surgery and µCT-analysis were used to evaluate the healing results in a rat osteotomy model of biologically impaired healing. Then, bones were processed for histological evaluation. Preliminary in vivo results demonstrated that incorporation of MBGs into a TSH is a promising strategy to design a multifunctional injectable formulation for in situ and sustained delivery of pro-osteogenic species enhancing bone regeneration

Surgical failure, mainly caused by loosening implants, causes great mental and physical trauma to patients. Improving the physicochemical properties of implants to achieve favourable osseointegration will continue to be the focus of future research. Strontium (Sr), a trace element, is often incorporated into hydroxyapatite (HA) to improve its osteogenic activity. Our previous studies have shown that miR-21 can promote the osteogenic differentiation of mesenchymal stem cells by the PI3K/β-catenin pathway. The aim of this study is to fabricate a SrHA and miR-21 composite coating and it is expected to have a favorable bone healing capability. Ti discs (20 mm diameter and one mm thickness for the in vitro section) and rods (four mm diameter and seven mm length for the in vivo section) were prepared by machining pure Ti. The Ti cylinders were placed in a Teflon-lined stainless-steel autoclave for treating at 150°C for 24 h to form SrHA layer. The miR-21 was encapsulated in nanocapsules. The miR-21 nanocapsules were mixed with CMCS powder to form a gel-like sample and uniformly coated on the SrHA modifed Ti. Osteoblast-like MG63 cells were cultured on SrHA and miR-21 modified Ti, Cell proliferation activity and osteogenesis-related gene expression were evaluated. A bone defect model was established with mature New Zealand to evaluate the osseointegration. Cylindrical holes (four mm in diameter) were created at the distal femur and tibial plateau. Each rabbit was implanted with four of the aforementioned rods (distal femur and tibial plateau of the hind legs). After implantation for one, two and three months, the rabbits were observed by X-ray and scanned using u-CT. Histological and Immunohistochemical analysis were performed to examine the osteogenic markers. A biomechanical push-in test was used to assess the bone-implant bonding strength. Both SrHA nanoparticles with good superhydrophilicity and miR-21 nanocapsules with uniform sizes were distributed evenly on the surface of the Ti. In vitro experiments revealed that the composite coating was beneficial to osteoblast proliferation, differentiation and mineralization. In vivo evaluations demonstrated that this coating could not only promote the expression of angiogenic factor CD31 but also enhance the expression of osteoblastic genes to facilitate angio-osteogenesis. In addition, the composite coating also showed a decreased RANKL expression compared with the miR-21 coating. As a result, the SrHA/miR-21 composite coating promoted new bone formation and mineralization and thus enhanced osseointegration and bone-implant bonding strength. A homogeneous SrHA and miR-21 composite coating was fabricated by generating pure Ti through a hydrothermal process, followed by adhering miR-21 nanocapsules. This coating combined the favorable physicochemical properties of SrHA and miR-21 that synergistically promoted angiogenesis, osteogenesis, osseointegration, bone mineralization and thus bone-implant bonding strength. This study provided a new strategy for surface modification of biomedical implants

Aims

Bone health assessment and the prescription of medication for secondary fracture prevention have become an integral part of the acute management of patients with hip fracture. However, there is little evidence regarding compliance with prescription guidelines and subsequent adherence to medication in this patient group.

The nature of the initial interaction between calcium phosphate (CaP) thin films and osteoblasts can be mediated by the outermost surface properties of that material. As such, the phase, crystallinity, stoichiometry, composition and morphology of the CaP surfaces are seen as key parameters that must be accurately controlled in order to influence their potential biofunctionality with respect to osteoblasts. Hydroxyapatite [HA – Ca. 10. (PO. 4. ). 6. (OH). 2. ] has been extensively studied due to the structural and chemical similarities demonstrated with the main inorganic constituent of bone tissue and teeth. However, it is well documented that biological hydroxyapatite, which forms the mineral phases of calcified tissues, differ from pure and synthetically produced HA. Biological apatite is comprised of a mixture of calcium phosphate phases and trace elements, e.g., strontium, zinc, magnesium and silicon. As such, when designing CaP biomaterials for clinical use (both bulk materials and coatings) one proposed route would be to introduce multiple ionic substitutions into HA in order to mimic the complex chemistry of human bone and thereby improve the biological performance of such materials, both in vitro and in vivo. This presentation will explore a novel approach to depositing substituted and co-substituted CaP systems onto a range of different substrates types, namely metal and polymers. In particular, this presentation will examine how the surface properties of bioinert polymers, such as Poly(etheretherketone) (PEEK) accurately controlled in order to provide an enhanced in vitro performance. The presentation will also look at how resorbable magnesium implants can also be manipulated to provide both enhanced bioactivity and to provide a route to control how they resorb in a physiological environment

In order to evaluate the feasibility of zinc alloys as future biodegradable bone implant materials, the mechanical properties, corrosion resistance, hemocompatibility, cell activity, proliferation and adhesion, in vivo animal implantation experiments have been employed. The experimental results show that the alloying element magnesium, calcium and strontium can significantly improve the mechanical properties of pure zinc, and further deformation processes can further improve the mechanical properties of zinc alloys. Alloying elements can effectively control the corrosion rates of zinc alloys, which are between the rates of magnesium alloys and iron alloys. Zinc and zinc alloys exhibit excellent hemocompatibility and the hemolysis rate is far lower than 5%. After adding alloying elements Mg, Ca and Sr, MG63 and ECV304 cell proliferation rate and activity increased significantly, while for VSMC cell, the influence of alloying elements effect is not obvious. Zinc alloy intramedullary pins can effectively promote the new bone formation, and after 2 months implanted in mice femur, they still maintained a relatively complete structure, indicating that they are able to provide enough mechanical strength and thus more conducive to bone tissue repair and healing

Abstract. Distraction Osteogenesis (DO) for the management of bone defects in long bones is an established technique. Problems with bone regeneration are a common occurrence and literature is full of different modalities to enhance regenerate formation and quality. Strontium Ranelate (SR) has a dual mode of action and enhances bone formation in addition to decreasing osteoclastic activity. Due to this dual mode of action as well as ease of administration in a suspension form, it makes an ideal drug in scenarios where realignment of bone homeostasis towards positive bone balance is desirable. We studied the relationship of administration of SR with rate of regenerate progression, docking site union and complications associated with bone transport in 48 patients undergoing bone transport for management of bone defects. The findings of our retrospective observation study indicated that compliant use of SR was associated with good regenerate progression, decreased problems with docking site union and decreased the need for additional interventions

Aims

The success of anterior cruciate ligament reconstruction (ACLR) depends on osseointegration at the graft-tunnel interface and intra-articular ligamentization. Our aim was to conduct a systematic review of clinical and preclinical studies that evaluated biological augmentation of graft healing in ACLR.

Osteoporosis is a systemic skeletal disorder characterized by reduced bone mass and deterioration of bone microarchitecture, which results in increased bone fragility and fracture risk. Casein kinase 2-interacting protein-1 (CKIP-1) is a protein that plays an important role in regulation of bone formation. The effect of CKIP-1 on bone formation is mainly mediated through negative regulation of the bone morphogenetic protein pathway. In addition, CKIP-1 has an important role in the progression of osteoporosis. This review provides a summary of the recent studies on the role of CKIP-1 in osteoporosis development and treatment.

Cite this article: X. Peng, X. Wu, J. Zhang, G. Zhang, G. Li, X. Pan. The role of CKIP-1 in osteoporosis development and treatment. Bone Joint Res 2018;7:173–178. DOI: 10.1302/2046-3758.72.BJR-2017-0172.R1.

Osteoporosis is a major healthcare burden, responsible for significant morbidity and mortality. Manipulating bone homeostasis would be invaluable in treating osteoporosis and optimising implant osseointegration. Strontium increases bone density through increased osteoblastogenesis, increased bone mineralisation, and reduced osteoclast activity. However, oral treatment may have significant side effects, precluding widespread use. We have recently shown that controlled disorder nanopatterned surfaces can control osteoblast differentiation and bone formation. We aimed to combine the osteogenic synergy of nanopatterning with local strontium delivery to avoid systemic side effects. Using a sol-gel technique we developed strontium doped and/or nanopatterned titanium surfaces, with flat titanium controls including osteogenic and strontium doped media controls. These were characterised using atomic force microscopy and ICP-mass spectroscopy. Cellular response assessed using human osteoblast/osteoclast co-cultures including scanning electron microscopy, quantitative immunofluorescence, histochemical staining, ELISA and PCR techniques. We further performed RNAseq gene pathway combined with metabolomic pathway analysis to build gene/metabolite networks. The surfaces eluted 800ng/cm2 strontium over 35 days with good surface fidelity. Osteoblast differentiation and bone formation increased significantly compared to controls and equivalently to oral treatment, suggesting improved osseointegration. Osteoclast pre-cursor survival and differentiation reduced via increased production of osteoprotegrin. We further delineated the complex cellular signalling and metabolic pathways involved including unique targets involved in osteoporosis. We have developed unique nanopatterned strontium eluting surfaces that significantly increase bone formation and reduce osteoclastogenesis. This synergistic combination of topography and chemistry has great potential merit in fusion surgery and arthroplasty, as well as providing potential targets to treat osteoporosis

Aims

Ceramic-on-ceramic (CoC) bearings in total hip arthroplasty (THA) are commonly used, but concerns exist regarding ceramic fracture. This study aims to report the risk of revision for fracture of modern CoC bearings and identify factors that might influence this risk, using data from the National Joint Registry (NJR) for England, Wales, Northern Ireland and the Isle of Man.