Aseptic loosening

Inflammatory bowel disease patients undergoing total hip arthroplasty have higher odds of implant-related complications

PURPOSE

This study evaluates whether IBD patients are at increased risk of implant-related complications after THA.

MATERIALS AND METHODS

A retrospective study from 01 January 2010 to 31 October 31 2020 using an administrative claims database was performed. IBD patients undergoing THA (n = 11,025), without corticosteroid treatment, were propensity score matched to controls in a 1:5 ratio (n = 55,121) based on age, sex, and the Charlson Comorbidity Index (CCI). Outcomes evaluated included periprosthetic fracture, aseptic loosening, prosthetic joint infection, and THA revision within 2 years of index procedure. Chi-square analyses were used to compare the matched cohorts. The association of IBD and implant-related complications was evaluated using logistical regression to calculate odds ratios (ORs), 95% confidence intervals (95% CIs), and p-values. A p-value < 0.001 was used as the significance threshold.

RESULTS

Patients with IBD had a greater incidence and odds of total implant complications (7.03% vs. 3.98%; OR 1.76; p < 0.001) compared with matched controls. IBD patients had significantly higher incidence and odds of developing periprosthetic fracture (0.50% vs. 0.20%; OR 2.46; p < 0.001), THA revisions (2.21% vs. 1.17%; OR 1.91; p < 0.001), aseptic loosening (1.45% vs. 0.84%; OR 1.75; p < 0.001), and prosthetic joint infection (2.87% vs. 1.77%; OR 1.64; p < 0.001).

CONCLUSIONS

Patients with IBD who underwent primary THA had a significantly higher risk of implant-related complications compared to matched controls. Providers should use this study to appropriately assess post-complication risk factors for their patients with IBD.

Orthopedic meta-implants

Meta-biomaterials, engineered materials with distinctive combinations of mechanical, physical, and biological properties stemming from their micro-architecture, have emerged as a promising domain within biomedical engineering. Correspondingly, meta-implants, which serve as the device counterparts of meta-biomaterials, offer exceptional functionalities, holding great potential for addressing complex skeletal diseases. This paper presents a comprehensive overview of the various types of meta-implants, including hybrid, shape-morphing, metallic clay, and deployable meta-implants, highlighting their unprecedented properties and recent achievement in the field. This paper also delves into the potential future developments of meta-implants, addressing the exploration of multi-functionalities in meta-biomaterials and their applications in diverse biomedical fields.

Diagnostic value of VEGF in peri-implantitis and its correlation with titanium particles: A controlled clinical study

OBJECTIVES

VEGF is prototypic marker of neovascularization, repeatedly proposed as intrinsic characteristic of peri-implantitis. This study aimed to assess pattern of VEGF in peri-implantitis, its correlation with titanium particles (TPs) and capacity as respective biomarker.

MATERIAL AND METHODS

Pathological specificity of VEGF was assessed in peri-implant granulations using immunohistochemistry, periodontal granulations represented Ti-free positive controls. VEGF was correlated to TPs, identified using scanning electron microscopy coupled with dispersive x-ray spectrometry. Diagnostic accuracy, sensitivity and specificity of VEGF were estimated in PICF specimens from peri-implantitis, peri-implant mucositis (PIM) and healthy peri-implant tissues (HI) using machine learning algorithms.

RESULTS

Peri-implantitis exhibited rich neovascular network with expressed density in contact zones toward neutrophil infiltrates without specific pattern variations around TPs, identified in all peri-implantitis specimens (mean particle size 8.9 ± 24.8 µm2; Ti-mass (%) 0.380 ± 0.163). VEGF was significantly more expressed in peri-implantitis (47,065 ± 24.2) compared to periodontitis (31,14 ± 9.15), and positively correlated with its soluble concentrations in PICF (p = 0.01). VEGF was positively correlated to all clinical endpoints and significantly increased in peri-implantitis compared to both PIM and HI, but despite high specificity (96%), its overall diagnostic capacity was average. Two patient clusters were identified in peri-implantitis, one with 8-fold higher VEGF values compared to HI, and second with lower values comparable to PIM.

SIGNIFICANCE

VEGF accurately reflects neovascularization in peri-implantitis that was expressed in contact zones toward implant surface without specific histopathological patter variation around TPs. VEGF answered requests for biomarker of peri-implantitis but further research is necessary to decrypt its exact underlying cause.

Isolation of TiNbN wear particles from a coated metal-on-metal bearing: Morphological characterization and in vitro evaluation of cytotoxicity in human osteoblasts

To improve the wear resistance of articulating metallic joint endoprostheses, the surfaces can be coated with titanium niobium nitride (TiNbN). Under poor tribological conditions or malalignment, wear can occur on these implant surfaces in situ. This study investigated the biological response of human osteoblasts to wear particles generated from TiNbN-coated hip implants. Abrasive particles were generated in a hip simulator according to ISO 14242-1/-2 and extracted with Proteinase K. Particle characteristics were evaluated by electron microscopy and energy dispersive x-ray spectroscopy (EDS), inductively coupled plasma mass spectrometry (ICP-MS) and dynamic light scattering (DLS) measurements. Human osteoblasts were exposed to different particle dilutions (1:20, 1:50, and 1:100), and cell viability and gene expression levels of osteogenic markers and inflammatory mediators were analyzed after 4 and 7 days. Using ICP-MS, EDS, and DLS measurements, ~70% of the particles were identified as TiNbN, ranging from 39 to 94 nm. The particles exhibited a flat and subangular morphology. Exposure to particles did not influence cell viability and osteoblastic differentiation capacity. Protein levels of collagen type 1, osteoprotegerin, and receptor activator of nuclear factor κB ligand were almost unaffected. Moreover, the pro-inflammatory response via interleukins 6 and 8 was minor induced after particle contact. A high number of TiNbN wear particles only slightly affected osteoblasts' differentiation ability and inflammatory response compared to metallic particles. Nevertheless, further studies should investigate the role of these particles in peri-implant bone tissue, especially concerning other cell types.

Survivability of Titanium Implant Materials: In Vitro Simulated Inflammatory and Infectious Environment

Titanium-based implants utilized in total joint arthroplasties could restore primary musculoskeletal function to patients suffering from osteoarthritis and other conditions. Implants are susceptible to failure stemming from aseptic loosening and infection at the joint site, eventually requiring revision surgery. We hypothesized that there might be a feedback loop by which metal degradation particles and ions released from the implant decrease cell viability and increase immune response, thereby creating biochemical conditions that increase the corrosion rate and release more metal ions. This study focused on the synergistic process through cell viability assays and electrochemical tests. From the results, inflammatory conditions from ion release resulting in cell death would further increase the corrosion rate at the metal implant site. The synergistic interaction in the implant surroundings in which infectious conditions produce Ti ions that contribute to more infection, creating a potential cycle of accelerating corrosion.

The acute inflammatory response to copper(II)-doped biphasic calcium phosphates

Infection and inflammation are two key features to consider to avoid septic or aseptic loosening of bone-implanted biomaterials. In this context, various approaches to fine-tune the biomaterial's properties have been studied in order to modulate the crosstalk between immune and skeletal cells. Cation-doping strategies for tuning of calcium phosphates properties has been evidenced as a promising way to control the biomaterial-induced inflammatory process, and thus improving their osteoimmunomodulatory properties. Copper(II) ions are recognized for their antibacterial potential, but the literature on their impact on particulate material-induced acute inflammation is scarce. We synthesized copper(II) ions-doped biphasic calcium phosphate (BCP), intended to exhibit osteoimmunomodulatory properties. We addressed in vitro, for the first time, the inflammatory response of human primary polymorphonuclear neutrophils (PMNs) to copper(II) ions-doped or undoped (BCP) powders, synthesized by an original and robust wet method, in the presence or absence of LPS as a costimulant to mimic an infectious environment. ELISA and zymography allowed us to evidence, in vitro, a specific increase in IL-8 and GRO-α secretion but not MIP-1β, TNF-α, or MMP-9, by PMNs. To assess in vivo relevance of these findings, we used a mouse air pouch model. Thanks to flow cytometry analysis, we highlighted an increased PMN recruitment with the copper(II) ions-doped samples compared to undoped samples. The immunomodulatory effect of copper(II) ions-doped BCP powders and the consequent induced moderate level of inflammation may promote bacterial clearance by PMNs in addition to the antimicrobial potential of the material. Copper(II) doping provides new insights into calcium phosphate (CaP)-based biomaterials for prosthesis coating or bone reconstruction by effectively modulating the inflammatory environment.

Mechanism of regulating macrophages/osteoclasts in attenuating wear particle-induced aseptic osteolysis

Joint replacement surgery is the most effective treatment for end-stage arthritis. Aseptic loosening caused by periprosthetic osteolysis is a common complication after joint replacement. Inflammation induced by wear particles derived from prosthetic biomaterials is a major cause of osteolysis. We emphasize that bone marrow-derived macrophages and their fusion-derived osteoclasts play a key role in this pathological process. Researchers have developed multiple intervention approaches to regulate macrophage/osteoclast activation. Aiming at wear particle-induced periprosthetic aseptic osteolysis, this review separately discusses the molecular mechanism of regulation of ROS formation and inflammatory response through intervention of macrophage/osteoclast RANKL-MAPKs-NF-κB pathway. These molecular mechanisms regulate osteoclast activation in different ways, but they are not isolated from each other. There is also a lot of crosstalk among the different mechanisms. In addition, other bone and joint diseases related to osteoclast activation are also briefly introduced. Therefore, we discuss these new findings in the context of existing work with a view to developing new strategies for wear particle-associated osteolysis based on the regulation of macrophages/osteoclasts.

ROS-mediated mitophagy and necroptosis regulate osteocytes death caused by TCP particles in MLO-Y4 cells

Our previous data have revealed TCP particles caused cell death of osteocytes, comprising over 95 % of all bone cells, which contribute to periprosthetic osteolysis, joint loosening and implant failure, but its mechanisms are not fully understood. Here, we reported that TCP particles inhibited cell viability of osteocytes MLO-Y4, and caused cell death. TCP particles caused mitochondrial impairment and increased expressions of LC-3 II, Parkin and PINK 1, accompanied by the elevation of autophagy flux and intracellular acidic components, the accumulation of LC-3II, PINK1 and Parkin in damaged mitochondria, and p62 reduction. The increased LC-3II expression and cell death extent were significantly enhanced by the autophagy inhibitor Baf A1, compared with Baf A1 (or TCP particles) alone, indicating that TCP particles increase autophagic flux and lead to cell even death of MLO-Y4 cells, closely associated with mitophagy. Furthermore, TCP particles induced propidium iodide (PI) uptake and the phosphorylation of RIP1, RIP3 and MLKL, thereby increasing necroptosis in MLO-Y4 cells. The pro-necroptotic effect was alleviated by the RIP1 inhibitor Nec-1 or the MLKL inhibitor NSA. Additionally, TCP particles promoted the production of intracellular reactive oxygen species (ROS) and mitochondrial ROS (mtROS), and increased TXNIP expression, but decreased protein levels of TRX1, Nrf2, HO-1 and NQO1, leading to oxidative stress. The ROS scavenger NAC remarkably reversed mitophagy and necroptosis caused by TCP particles, suggesting that ROS is responsible for mitophagy and necroptosis. Collectively, ROS-mediated mitophagy and necroptosis regulate osteocytes death caused by TCP particles in MLO-Y4 cells, which enhances osteoclastogenesis and periprosthetic osteolysis.

Matrix stiffness regulates osteoclast fate through integrin-dependent mechanotransduction

Osteoclasts ubiquitously participate in bone homeostasis, and their aberration leads to bone diseases, such as osteoporosis. Current clinical strategies by biochemical signaling molecules often perturb innate bone metabolism owing to the uncontrolled management of osteoclasts. Thus, an alternative strategy of precise regulation for osteoclast differentiation is urgently needed. To this end, this study proposed an assumption that mechanic stimulation might be a potential strategy. Here, a hydrogel was created to imitate the physiological bone microenvironment, with stiffnesses ranging from 2.43kPa to 68.2kPa. The impact of matrix stiffness on osteoclast behaviors was thoroughly investigated. Results showed that matrix stiffness could be harnessed for directing osteoclast fate in vitro and in vivo. In particular, increased matrix stiffness inhibited the integrin β3-responsive RhoA-ROCK2-YAP-related mechanotransduction and promoted osteoclastogenesis. Notably, preosteoclast development is facilitated by medium-stiffness hydrogel (M-gel) possessing the same stiffness as vessel ranging from 17.5 kPa to 44.6 kPa by partial suppression of mechanotransduction, which subsequently encouraged revascularization and bone regeneration in mice with bone defects. Our works provide an innovative approach for finely regulating osteoclast differentiation by selecting the optimum matrix stiffness and enable us further to develop a matrix stiffness-based strategy for bone tissue engineering.

3D Biomimetic Calcified Cartilaginous Callus that Induces Type H Vessels Formation and Osteoclastogenesis

The formation of a calcified cartilaginous callus (CACC) is crucial during bone repair. CACC can stimulate the invasion of type H vessels into the callus to couple angiogenesis and osteogenesis, induce osteoclastogenesis to resorb the calcified matrix, and promote osteoclast secretion of factors to enhance osteogenesis, ultimately achieving the replacement of cartilage with bone. In this study, a porous polycaprolactone/hydroxyapatite-iminodiacetic acid-deferoxamine (PCL/HA-SF-DFO) 3D biomimetic CACC is developed using 3D printing. The porous structure can mimic the pores formed by the matrix metalloproteinase degradation of the cartilaginous matrix, HA-containing PCL can mimic the calcified cartilaginous matrix, and SF anchors DFO onto HA for the slow release of DFO. The in vitro results show that the scaffold significantly enhances angiogenesis, promotes osteoclastogenesis and resorption by osteoclasts, and enhances the osteogenic differentiation of bone marrow stromal stem cells by promoting collagen triple helix repeat-containing 1 expression by osteoclasts. The in vivo results show that the scaffold significantly promotes type H vessels formation and the expression of coupling factors to promote osteogenesis, ultimately enhancing the regeneration of large-segment bone defects in rats and preventing dislodging of the internal fixation screw. In conclusion, the scaffold inspired by biological bone repair processes effectively promotes bone regeneration.

Investigation of the Friction Properties of a New Artificial Imitation Cartilage Material: PHEMA/Glycerol Gel

The absence of artificial articular cartilage could cause the failure of artificial joints due to excessive material wear. There has been limited research on alternative materials for articular cartilage in joint prostheses, with few reducing the friction coefficient of artificial cartilage prostheses to the range of the natural cartilage friction coefficient (0.001-0.03). This work aimed to obtain and characterize mechanically and tribologically a new gel for potential application in articular replacement. Therefore, poly(hydroxyethyl methacrylate) (PHEMA)/glycerol synthetic gel was developed as a new type of artificial joint cartilage with a low friction coefficient, especially in calf serum. This glycerol material was developed via mixing HEMA and glycerin at a mass ratio of 1:1. The mechanical properties were studied, and it was found that the hardness of the synthetic gel was close to that of natural cartilage. The tribological performance of the synthetic gel was investigated using a reciprocating ball-on-plate rig. The ball samples were made of a cobalt-chromium-molybdenum (Co-Cr-Mo) alloy, and the plates were synthetic glycerol gel and two additional materials for comparison, which were ultra-high molecular polyethylene (UHMWPE) and 316L stainless steel. It was found that synthetic gel exhibited the lowest friction coefficient in both calf serum (0.018) and deionized water (0.039) compared to the other two conventional materials for knee prostheses. The surface roughness of the gel was found to be 4-5 μm through morphological analysis of wear. This newly proposed material provided a possible solution as a type of cartilage composite coating with hardness and tribological performance close to the nature of use in wear couples with artificial joints.

Carboxymethyl chitosan regulates oxidative stress and decreases the expression levels of tumor necrosis factor α in macrophages induced by wear particles

The aim of the present study was to determine the effects of carboxymethyl chitosan (CMC) on titanium particles-induced oxidative stress in mouse RAW264.7 macrophages. The mouse RAW264.7 macrophages were divided into four groups: (i) the control group; (ii) the CMC group received stimulation of CMC for 4 h; (iii) the titanium particles group received stimulation of titanium particles for 12 h; and (iv) the CMC group received pre-stimulation of CMC hydrogels for 4 h followed by treatment of titanium particles for 12 h. Afterwards, reactive oxygen species (ROS) level in the cells was measured by flow cytometry. A spectrophotometer was used to measure the activities of oxidases and antioxidant enzymes. Fluorescence quantitative PCR was performed to analyze mRNA levels of enzymes and tumor necrosis factor α (TNF-α). ELISA was used to detect the mass concentration of TNF-α after indicated treatment. CMC effectively suppressed titanium particles-induced oxidative stress in RAW264.7 cells, as evidenced by the decrease in intracellular ROS level, the transcription of oxidases, and TNF-α concentration as well as the increase in the transcription of antioxidant enzymes. CMC exerts a protective impact against wear particles-induced oxidative stress and reduces the release of TNF-α in RAW264.7 cells.

Copper modified cobalt-chromium particles for attenuating wear particle induced-inflammation and osteoclastogenesis

The nature of aseptic prosthetic loosening mainly relates to the wear particles that induce inflammation and subsequent osteoclastogenesis. The ideal approach to impede wear particle-induced osteolysis should minimize inflammation and osteoclastogenesis. In this work, Co29Cr9W3Cu particles were used as a research model for the first time to explore the response of Co29Cr9W3Cu particles to inflammatory response and osteoclast activation in vitro and in vivo by using Co29Cr9W particles as the control group. In vitro studies showed that the Co29Cr9W3Cu particles could promote the generation of M2-phenotype macrophages and increase the expression level of anti-inflammatory factor IL-10, while inhibiting the formation of M1-phenotype macrophages and down-regulating the expression of inflammatory factors TNF-α, IL-6 and IL-1β; More importantly, the Co29Cr9W3Cu particles reduced the expression of NF-κB and downstream osteoclast related-specific transcription marker genes, such as TRAP, NFATc1, and Cath-K; In vivo results indicated that the Co29Cr9W3Cu particles exposed to murine calvarial contributed to decreasing the amount of osteoclast and osteolysis area. These findings collectively demonstrated that Cu-bearing cobalt-chromium alloy may potentially delay the development of aseptic prosthetic loosening induced by wear particles, which is expected to provide evidence of Co29Cr9W3Cu alloy as an alternative material of joint implants with anti-wear associated osteolysis.

Clearance of senescent cells by navitoclax (ABT263) rejuvenates UHMWPE-induced osteolysis

Periprosthetic osteolysis is the leading cause of prosthesis failure and subsequent total joint revision. Wear particles produced by prosthetic materials are the main biological factors that cause periprosthetic osteolysis. Reducing the inflammatory response induced by the phagocytosis of wear particles by macrophages, blocking the activation of osteoclastogenesis, and promoting bone regeneration are essential for preventing the aseptic loosening of prostheses. In this study, we demonstrated that cellular senescence played a vital role during the process of ultra-high molecular weight polyethylene (UHMWPE) particle-induced osteolysis. Administration of the senolytic drug navitoclax (ABT263) could eliminate senescent cells and inhibit the secretion and inflammatory state of the senescence-associated secretory phenotype (SASP). We also discovered that ABT263 inhibited the formation of osteoclasts and had a significant therapeutic effect on UHMWPE particle-induced osteolysis based on the results of UHMWPE-induced mouse cranial osteolysis. Therefore, our research provided innovative strategies and ideas for the prevention and treatment of periprosthetic osteolysis.

Dental implant material related changes in molecular signatures in peri-implantitis - A systematic review and integrative analysis of omics in-vitro studies

OBJECTIVE

Since peri-implantitis differs clinically and histopathologically from periodontitis, implant wear debris is considered to play a role in the destructive processes. This work aims to systematically review if titanium particles affect oral-related cells through changes in molecular signatures (e.g., transcriptome, proteome, epigenome), thereby promoting peri-implantitis.

METHODS

Leveraging three literature databases (Medline, Embase, Cochrane) a systematic search based on a priori defined PICOs was conducted: '-omics' studies examining titanium exposure in oral-related cells. After risk of bias assessments, lists of differentially expressed genes, proteins, and results of functional enrichment analyses were compiled. The significance of overlapping genes across multiple studies was assessed via Monte Carlo simulation and their ranking was verified using rank aggregation.

RESULTS

Out of 2104 screened articles we found 12 eligible publications. A significant overlap of gene expression in oral-related cells exposed to titanium particles was found in four studies. Furthermore, changes in biological processes like immune/inflammatory or stress response as well as toll-like receptor (TLR) and mitogen-activated protein kinase (MAPK) signaling pathways were linked to titanium in transcriptome and proteome studies. Epigenetic changes caused by titanium were detected but inconsistent.

CONCLUSION

An influence of titanium implant wear debris on the development and progression of peri-implantitis is plausible but needs to be proven in further studies. Limitations arise from small sample sizes of included studies and insufficient publication of re-analyzable data.

IL-1 β gene (+3954 C/T, exon 5, rs1143634) and NOS2 (exon 22) polymorphisms associate with early aseptic loosening of arthroplasties

Aseptic prosthetic loosening (APL) and prosthetic joint infections (PJI) are frequent complications of hip and knee implants. Polymorphisms of cytokines and nitric oxide (NO), key inflammatory molecules in APL and PJI pathogenesis, could explain individual susceptibility to these complications. Three cytokines (IL-1-a, IL-1-β, TNF-α) and two nitric oxide synthase (NOS2, NOS3) genes polymorphisms were genotyped in 77 APL and 117 PJI patients and 145 controls with aseptic hip or knee implants that were implanted for > 16 years. Plasma cytokines and nitrate-nitrite (NOx) levels also were measured. The TT genotype and T allele of (+3954 C/T, exon 5, rs1143634) IL-1β polymorphism were more frequent in APL patients compared to controls (P = 0.03 and P = 0.02, respectively). No genotypic associations in PJI patients were observed. Plasma IL-6, TNF-α and NOx were significantly different between APL and controls (P < 0.0001). Plasma IL-1β and IL-6 were significantly higher in APL T allele carriers vs. non-carriers (P < 0.03). Knee implant (HR 2.488, 95% CI 1.307-4.739, P = 0.005), male gender (HR 2.252, 95% CI 1.121-4.525, P = 0.023), carriages of the TT genotype of the (+3954 C/T) IL-1β polymorphism (HR 3.704, 95% CI 1.274-10.753, P = 0.016) and AA genotype of the (exon 22) NOS2 polymorphism (HR 3.509, 95% CI 1.266-9.709, P = 0.016) were independently associated with a shorter implant survival by Cox regression. No genotypic associations in PJI patients were observed. Genotyping of IL-1β (+3954 C/T, exon 5, rs1143634) and NOS2 (exon 22) polymorphisms could be useful as predictors of early hip or knee APL.

Biocompatible Nanocapsules for Self-Healing Dental Resins and Bone Cements

Bone cements and dental resins are methacrylate-based materials that have been in use for many years, but their failure rates are quite high with essentially all dental resins failing within 10 years and 25% of all prosthetic implants will undergo aseptic loosening. There are significant healthcare costs and impacts on quality of life of patients. Self-healing bone cements and resins could improve the lifespan of these systems, reduce costs, and improve patient outcomes, but they have been limited by efficacy and toxicity of the components. To address these issues, we developed a self-healing system based on a dual nanocapsule system. Two nanocapsules were synthesized, one containing an initiator and one encapsulating a monomer, both in polyurethane shells. The monomer used was triethylene glycol dimethacrylate. The initiator capsules synthesized contained benzoyl peroxide and butylated hydroxytoluene. Resins containing the nanocapsules were tested in tension until failure, and the fractured surfaces were placed together. 33% of the samples showed self-healing behaviors to the point where they could be reloaded and tested in tension. Furthermore, the capsules and their components showed good biocompatibility with Caco-2 cells, a human epithelial cell line suggesting that they would be well tolerated in vivo.

Analysis of the Effect of Component Ratio Imbalances on Selected Mechanical Properties of Seasoned, Medium Viscosity Bone Cements

The paper presents the results of experimental strength tests of specimens made of two commercially available bone cements subjected to compression, that is a typical variant of load of this material during use in the human body, after it has been used for implantation of prostheses or supplementation of bone defects. One of the factors analysed in detail was the duration of cement seasoning in Ringer's solution that simulates the aggressive environment of the human body and material degradation caused by it. The study also focused on the parameters of quantitative deviation from the recommended proportions of liquid (MMA monomer, accelerator and stabiliser) and powder (PMMA prepolymer and initiator) components, i.e., unintentional inaccuracy of component proportioning at the stage of cement mass preparation. Statistical analysis has shown the influence of these factors on the decrease in compressive strength of the cements studied, which may be of significant importance in operational practice.

Protective effect of zinc supplementation on tricalcium phosphate particles-induced inflammatory osteolysis in mice

Zinc (Zn), an essential trace element, can stimulate bone formation and inhibit osteoclastic bone resorption, which controls the growth and maintenance of bone. However, the effect of Zn supplementation on tricalcium phosphate (TCP) wear particles-induced osteolysis remains unknown. Here, we doped Zn into TCP particles (ZnTCP), and explore the protective effects of Zn on TCP particles-induced osteolysis in vivo. TCP particles and ZnTCP particles were embedded under the periosteum around the middle suture of the mouse calvaria. After 2 weeks, blood, the periosteal tissue, and the calvaria were collected to determine serum levels of Zn and osteocalcin, pro-inflammatory cytokines, bone biochemical markers, osteoclastogenesis and bone resorption area, and to explain its mechanism. Data revealed that Zn significantly prevented TCP particles-induced osteoclastogenesis and bone loss, and increased bone turnover. The Zn supplement remarkably suppressed the release of pro-inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Immunoblotting demonstrated that Zn alleviated expression levels of ER stress-related proteins such as glucose-regulated protein 78 (GRP78), PKR-like ER kinase (PERK), phospho-PERK (p-PERK), eukaryotic initiation factor 2α (eIF2α), phospho-eIF2α (p-eIF2α), activating transcription factor 4 (ATF4), inositol-requiring enzyme 1α (IRE1-α) and transcription factor X-box binding protein spliced (XBP1s), leading to decreasing the ratios of p-PERK/PERK and p-eIF2α/eIF2α. Taken together, Zn supplementation strongly prevents TCP particles-induced periprosthetic osteolysis via inhibition of the ER stress pathway, and it may be a novel therapeutic approach for the treatment of aseptic prosthesis loosening.

Biomechanical Test of a New Endoprosthesis for Cylindrical Medullary Canals in Dogs

Exo-endoprosthesis is a limb salvage procedure for animals, although only expensive metal devices have been described. Now-a-days, new materials for this type of implant could be considered due to novel and affordable manufacturing techniques. However, a factor of safety (FoS) should be considered. There are kinetic and kinematic studies of canine natural gaits, which can be used to establish an FoS for mechanical tests for new non-metallic devices. Polyetheretherketone (PEEK) is used in different specialties in human medicine. Its mechanical properties (and its close mechanical stiffness to that of bone) make this polymer an alternative to metals in veterinary traumatology. PEEK could also be used in 3D printing. The suitability of a novel inner part of an exo-endoprosthesis manufactured by fuse deposition modeling (FDM) was presented in this study for long canine bones. Mechanical characterization of 3D-printed PEEK material and ex vivo mechanical tests of a customized endoprosthesis were performed to address it. Young's modulus of 3D-printed PEEK suffered a reduction of 30% in relation to bulk PEEK. Customized 3D-printed PEEK endoprostheses had promising outcomes for the tibiae of 20 kg dogs. Pure compression tests of the non-inserted endoprostheses showed a maximum force of 936 ± 199 N. In the bending tests of non-inserted endoprostheses, the PEEK part remained intact. Quasistatic mechanical tests of bone-inserted endoprostheses (compression-bending and pure compression tests) reached a maximum force of 785 ± 101 N and 1,642 ± 447 N, respectively. In fatigue tests, the samples reached 500,000 cycles without failure or detriment to their quasistatic results. These outcomes surpass the natural weight-bearing of dogs, even during a galloping pace. In conclusion, the 3D-printed PEEK part of the endoprosthesis for an exo-endoprosthesis can withstand loading, even during a galloping pace.

Surface coating of orthopedic implant to enhance the osseointegration and reduction of bacterial colonization: a review

The use of orthopedic implants in surgical technology has fostered restoration of physiological functions. Along with successful treatment, orthopedic implants suffer from various complications and fail to offer functions correspondent to native physiology. The major problems include aseptic and septic loosening due to bone nonunion and implant site infection due to bacterial colonization. Crucial advances in material selection in the design and development of coating matrixes an opportunity for the prevention of implant failure. However, many coating materials are limited in in-vitro testing and few of them thrive in clinical tests. The rate of implant failure has surged with the increasing rates of revision surgery creating physical and sensitive discomfort as well as economic burdens. To overcome critical pathogenic activities several systematic coating techniques have been developed offering excellent results that combat infection and enhance bone integration. This review article includes some more common implant coating matrixes with excellent in vitro and in vivo results focusing on infection rates, causes, complications, coating materials, host immune responses and significant research gaps. This study provides a comprehensive overview of potential coating technology, with functional combination coatings which are focused on ultimate clinical practice with substantial improvement on in-vivo tests. This includes the development of rapidly growing hydrogel coating techniques with the potential to generate several accurate and precise coating procedures.

Highly cross-linked polyethylene in primary total knee arthroplasty is associated with a lower rate of revision for aseptic loosening: a meta-analysis of 962,467 cases

BACKGROUND

The evolution in total knee arthroplasty (TKA) includes the highly cross-linked polyethylene (HXLPE) which has been reported as an effective manner to reduce the wear of the polyethylene and the osteolysis. The purpose of the present study is to synthesize the results of comparative studies between HXLPE and conventional polyethylenes and determine their effect in primary TKA.

METHODS

The US National Library of Medicine (PubMed/MEDLINE) and the Cochrane Database of Systematic Reviews were queried for publications utilizing the following keywords: "cross-linked", "polyethylene", "HXLPE", "conventional", "total knee arthroplasty", "TKA", "total knee replacement" and "TKR" combined with Boolean operators AND and OR.

RESULTS

Ten studies met the inclusion criteria and were included in the present meta-analysis with 962,467 patients. No significant difference was found regarding the revision rate for any reason between the patients who received HXLPE and those with conventional liner (OR 0.67; 95% CI 0.39-1.18; I²: 97.7%). In addition, there was no difference regarding the radiolucent lines between the two types of liners (OR 0.54; 95% CI 0.20-1.49; I²: 69.4%). However, with data coming from seven studies enrolling a total of 411,543 patients, it was demonstrated that patients who received HXLPE were less likely to be revised due to aseptic loosening compared to the patients with conventional liners (OR 0.35; 95% CI 0.31-0.39; I²: 0.0%).

CONCLUSION

The present meta-analysis showed that regarding the overall revision rate and radiographic outcomes there was no significant difference between the two types of liners. On the other hand, the significantly less revision rate due to loosening supports the routine continued use of HXLPE in primary TKA.

Synthesis and Characterization of Ti-Ta-Shape Memory Surface Alloys Formed by the Electron-Beam Additive Technique

The electron-beam cycling additive technique was proposed for the formation of shape memory Ti-Ta coatings on titanium substrate. On a commercially pure Ti plate, Ta film with a thickness of about 4 μm was deposited by direct current (DC) magnetron sputtering. The sample was then subjected to an electron-beam surface alloying by a scanning electron beam. On the already-formed Ti-Ta surface alloy, a Ta coating with the same thickness was further deposited and the specimen was again subjected to electron-beam alloying for the second cycle. The same procedure was repeated for the third cycle. The structure obtained after each cycle Ti-Ta coatings was studied by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX). The Young’s modulus, hardness, and shape memory effect (SME) were studied by nanoindentation experiments. The results showed that the thickness of the Ti-Ta coatings is about 50 μm in all cases, where the Ta content increases after each technological cycle. It was found that the obtained phase composition is in the form of a double-phase structure of α’ martensitic and β phases, where the highest amount of beta is registered in the case of the Ti-Ta coating obtained after the third cycle. The results obtained for the Young’s modulus and hardness showed that both mechanical characteristics decrease significantly after each cycle. Additionally, the elastic depth recovery ratio increases with an increase in the number of cycles.

Multinucleated Giant Cells: Current Insights in Phenotype, Biological Activities, and Mechanism of Formation

Monocytes and macrophages are innate immune cells with diverse functions ranging from phagocytosis of microorganisms to forming a bridge with the adaptive immune system. A lesser-known attribute of macrophages is their ability to fuse with each other to form multinucleated giant cells. Based on their morphology and functional characteristics, there are in general three types of multinucleated giant cells including osteoclasts, foreign body giant cells and Langhans giant cells. Osteoclasts are bone resorbing cells and under physiological conditions they participate in bone remodeling. However, under pathological conditions such as rheumatoid arthritis and osteoporosis, osteoclasts are responsible for bone destruction and bone loss. Foreign body giant cells and Langhans giant cells appear only under pathological conditions. While foreign body giant cells are found in immune reactions against foreign material, including implants, Langhans giant cells are associated with granulomas in infectious and non-infectious diseases. The functionality and fusion mechanism of osteoclasts are being elucidated, however, our knowledge on the functions of foreign body giant cells and Langhans giant cells is limited. In this review, we describe and compare the phenotypic aspects, biological and functional activities of the three types of multinucleated giant cells. Furthermore, we provide an overview of the multinucleation process and highlight key molecules in the different phases of macrophage fusion.

Total Hip Replacement in Patients with Rheumatoid Arthritis: Trends in Incidence and Complication Rates Over 35 Years

INTRODUCTION

Advances in rheumatoid arthritis (RA) management have made disease remission achievable. We evaluated trends in total hip replacement (THR) and postoperative outcomes in patients with RA in Western Australia (WA) over more than three decades.

METHODS

This was a retrospective analysis of routinely collected prospective data from a state-wide registry containing longitudinally linked administrative health data based on International Classification of Diseases (ICD) diagnostic and procedural codes. We included patients with two or more diagnostic codes for RA (between 1980 and 2015) and studied THR incidence rates (THR IR) and complication rates (revision, peri-prosthetic fracture, infection, venous thrombosis, and mechanical loosening). Survival rates were estimated by Kaplan-Meier method and predictors analyzed by Cox regression.

RESULTS

We followed 9201 RA patients over 111,625 person-years, during which 1560 patients (16.9%) underwent THR. From 1985 to 2015, THR IR (per 1000 RA patient-years) decreased from 20.8 (95% CI 20.1-21.5) to 7.3 (95% CI 7.2-7.5), and 5-year THR-free survival increased from 84.3 to 95.3% (1980-2015). Ten-year prosthetic survival was 91.2%. Complication rates in the first 5 years post-THR decreased significantly from 13.1 to 3.7% (p < 0.001). Mechanical complications such as loosening and periprosthetic fracture rates decreased significantly (> 35%, P < 0.05), while infection and revision did not change over the observation period (p > 0.05).

CONCLUSIONS

Over the last 30 years in RA patients, THR IR and mechanical complication rates decreased significantly, but the medical complication of infection has not changed significantly.

Chrysin Protects Against Titanium Particle-Induced Osteolysis by Attenuating Osteoclast Formation and Function by Inhibiting NF-κB and MAPK Signaling

Bone homeostasis only exists when the physical function of osteoblast and osteoclast stays in the balance between bone formation and resorption. Bone resorption occurs when the two processes are uncoupled, shifting the balance in favour of bone resorption. Excessive activation of osteoclasts leads to a range of osteolytic bone diseases including osteoporosis, aseptic prosthesis loosening, rheumatoid arthritis, and osteoarthritis. Receptor activator of nuclear factor kappa-B ligand (RANKL) and its downstream signaling pathways are recognized as key mediators that drive the formation and activation of osteoclastic function. Hence, osteoclast formation and/or its function remain as dominant targets for research and development of agents reaching the treatment towards osteolytic diseases. Chrysin (CHR) is a flavonoid with a wide range of anti-inflammatory and anti-tumor effects. However, its effect on osteoclasts remains unknown. In this study, we found the effects of CHR on inhibiting osteoclast differentiation which were assessed in terms of the number and size of TRAcP positive multinucleated osteoclasts (OCs). Further, the inhibitory effects of CHR on bone resorption and osteoclast fusion of pre-OC were assessed by hydroxyapatite resorption pit assay and F-actin belts staining; respectively. Western blotting analysis of RANKL-induced signaling pathways and immunofluorescence analysis for p65 nuclear translocation in response to RANKL-induced osteoclasts were used to analyze the mechanism of action of CHR affecting osteoclasts. Lastly, the murine calvarial osteolysis model revealed that CHR could protect against particle-induced bone destruction in vivo. Collectively, our data strongly suggested that CHR with its promising anti-tumor effects would also be a potential therapeutic agent for osteolytic diseases.

CoCrMo-Nanoparticles induced peri-implant osteolysis by promoting osteoblast ferroptosis via regulating Nrf2-ARE signalling pathway

Objectives

Aseptic loosening (AL) is the most common reason of total hip arthroplasty (THA) failure and revision surgery. Osteolysis, caused by wear particles released from implant surfaces, has a vital role in AL. Although previous studies suggest that wear particles always lead to osteoblast programmed death in the process of AL, the specific mechanism remains incompletely understood and osteoblast ferroptosis maybe a new mechanism of AL.

Materials and Methods

CoCrMo nanoparticles (CoNPs) were prepared to investigate the influence of ferroptosis in osteoblasts and calvaria resorption animal models. Periprosthetic osteolytic bone tissue was collected from patients who underwent AL after THA to verify osteoblast ferroptosis.

Results

Our study demonstrated that CoNPs induced significant ferroptosis in osteoblasts and particles induced osteolysis (PIO) animal models. Blocking ferroptosis with specific inhibitor Ferrostatin‐1 dramatically reduced particle‐induced ferroptosis in vitro. Moreover, in osteoblasts, CoNPs significantly downregulated the expression of Nrf2 (nuclear factor erythroid 2‐related factor 2), a core element in the antioxidant response. The overexpression of Nrf2 by siKeap1 or Nrf2 activator Oltipraz obviously upregulated antioxidant response elements (AREs) and suppressed ferroptosis in osteoblasts. Furthermore, in PIO animal models, the combined utilization of Ferrostatin‐1 and Oltipraz dramatically ameliorated ferroptosis and the severity of osteolysis.

Conclusions

These results indicate that CoNPs promote osteoblast ferroptosis by regulating the Nrf2‐ARE signalling pathway, which suggests a new mechanism underlying PIO and represents a potential therapeutic approach for AL.

Minimum 10-Year Results of Cementless Ceramic-On-Ceramic Total Hip Arthroplasty Performed With Transverse Subtrochanteric Osteotomy in Crowe Type IV Hips

BACKGROUND

Total hip arthroplasty (THA) performed for developmental dysplasia of the hip is a technically difficult procedure with a high complication rate, especially in the presence of completely dislocated hips. This study aimed to evaluate at least 10 years of follow-up results of cementless, ceramic-on-ceramic (CoC) THA performed with transverse subtrochanteric osteotomy in Crowe type IV hips.

METHODS

We retrospectively reviewed 50 patients' 67 hips that underwent CoC, cementless THA with transverse subtrochanteric osteotomy between 2008 and 2011. Clinical and radiological data of the hips were examined. Clinical results were evaluated using the Harris Hip Score and the Western Ontario and McMaster Universities Osteoarthritis Index.

RESULTS

The mean Harris Hip Score improved from 22.9 ± 9.9 preoperatively to 94.1 ± 8.1 at the final follow-up (P < 0.001). The median Western Ontario and McMaster Universities Osteoarthritis Index score improved from 72 (interquartile range: 17) preoperatively to 2 (interquartile range: 17) postoperatively (P < 0.001). The preoperative mean leg length discrepancy was improved from 4.9 ± 1 cm to 1.5 ± 1 cm in unilateral cases at the last follow-up (P < 0.001). Revision surgery was required because of nonunion in two patients, prosthetic infection in one patient, and aseptic femoral loosening in the other patient. The overall ten-year survival rate was 94% for femoral stems and 98.5% for acetabular components as per Kaplan-Meier survival analysis.

CONCLUSION

Transverse subtrochanteric shortening osteotomy combined with using cementless acetabular and femoral components with a CoC bearing surface promises successful clinical results and high prosthesis survival in the treatment of Crowe IV hips at long-term follow-up.

Targeting thymidine phosphorylase as a potential therapy for bone loss associated with periprosthetic osteolysis

Macrophages are generally thought to play a key role in the pathogenesis of aseptic loosening through initiating periprosthetic inflammation and pathological bone resorption. The aim of this study was to identify macrophage-derived factors that promote osteoclast differentiation and periprosthetic bone destruction. To achieve this, we examined the effects of 12 macrophage-derived factors that were identified by RNA-seq analysis of stimulated macrophages on osteoclast differentiation. Surprisingly, thymidine phosphorylase (TYMP) was found to trigger significant number of osteoclasts that exhibited resorbing activities on dentine slices. Functionally, TYMP knockdown reduced the number of osteoclasts in macrophages that had been stimulated with polyethylene debris. TYMP were detected in serum and synovial tissues of patients that had been diagnosed with aseptic loosening. Moreover, the administration of TYMP onto calvariae of mice induced pathological bone resorption that was accompanied by an excessive infiltration of inflammatory cells and osteoclasts. The RNA-seq for TYMP-induced-osteoclasts was then performed in an effort to understand action mode of TYMP. TYMP stimulation appeared to activate the tyrosine kinase FYN signaling associated with osteoclast formation. Oral administration of saracatinib, a FYN kinase inhibitor, significantly suppressed formation of bone osteolytic lesions in a polyethylene debris-induced osteolysis model. Our findings highlight a novel molecular target for therapeutic intervention in periprosthetic osteolysis.

sCD28, sCD80, sCTLA-4, and sBTLA Are Promising Markers in Diagnostic and Therapeutic Approaches for Aseptic Loosening and Periprosthetic Joint Infection

Aseptic prosthetic loosening and periprosthetic joint infections (PJI) are among the most frequent complications after total knee/hip joint arthroplasty (TJA). Current research efforts focus on understanding the involvement of the immune system in these frequent complications. Different immune cell types have already been implicated in aseptic prosthetic loosening and PJI. The aim of this study was to systematically analyze aspirates from knee and hip joints, evaluating the qualitative and quantitative composition of soluble immunoregulatory markers, with a focus on co-inhibitory and co-stimulatory markers. It has been shown that these molecules play important roles in immune regulation in cancer and chronic infectious diseases, but they have not been investigated in the context of joint replacement. For this purpose, aspirates from control joints (i.e., native joints without implanted prostheses), joints with TJA (no signs of infection or aseptic loosening), joints with aseptic implant failure (AIF; i.e., aseptic loosening), and joints with PJI were collected. Fourteen soluble immunoregulatory markers were assessed using bead-based multiplex assays. In this study, it could be shown that the concentrations of the analyzed immunoregulatory molecules vary between control, TJA, AIF, and PJI joints. Comparing TJA patients to CO patients, sCD80 was significantly elevated. The marker sBTLA was significantly elevated in AIF joints compared to TJA joints. In addition, a significant difference for eight markers could be shown when comparing the AIF and CO groups (sCD27, sCTLA-4, sCD137, sCD80, sCD28, sTIM-3, sPD-1, sBTLA). A significant difference was also reached for nine soluble markers when the PJI and CO groups were compared (sLAG-3, sCTLA-4, sCD27, sCD80, sCD28, sTIM-3, sPD-1, IDO, sBTLA). In summary, the analyzed immunoregulatory markers could be useful for diagnostic purposes as well as to develop new therapeutic approaches for AIF and PJI.

Understanding wear behavior of 3D-Printed calcium phosphate-reinforced CoCrMo in biologically relevant media

Recent advances in the processing of wear-resistant calcium-phosphate reinforced CoCrMo composites for articulating surface applications has necessitated further investigation of performance in biological conditions relevant to patient applications. To this end, CoCrMo composites containing calcium phosphate in the form of hydroxyapatite (HA) were manufactured to study the influence of the reinforcing phase on the tribofilm formation in biologically-relevant conditions. The CoCrMo-HA composites were processed using a laser engineered net shaping (LENS™) additive manufacturing (AM) system with three distinctive compositions: CoCrMo-0%HA, CoCrMo-1%HA, and CoCrMo-3%HA. Extensive wear testing of the CoCrMo-HA composites was carried out in DMEM (cell media) and DMEM + Hyaluronic acid (found naturally in synovial fluid). Wear tests were performed at loads ranging from 5N to 20N, and wear media was measured post-test using ICP-MS techniques to release Co and Cr ions. During testing, all coefficients of friction remained in the 0.15-0.25 range, which was lower than the previously reported 0.50-0.75 range in DI water, indicating that the DMEM + hyaluronic acid media plays a significant role in reducing frictional contact. At loads higher than 15N, the HA-tribofilm exhibited a breakdown resulting in higher wear rates but still lower overall ion release than the CoCrMo control composition. Our results indicate that CoCrMo alloys with HA addition can significantly reduce wear rates and ion release even in the presence of naturally-occurring synovial-fluid friction-reducing media.

Enalapril inhibits inflammatory osteolysis induced by wear debris in a mouse model

Objective

Aseptic loosening, the most frequent complication after total joint replacement, is probably caused by an inflammatory response to the shedding of wear debris from the implant. The only effective treatment is surgical revision. Using a mouse model, we investigated whether enalapril inhibits wear debris-induced inflammatory osteolysis.

Methods

Titanium (Ti) alloy particles were introduced, and calvarial bone from syngeneic mice was implanted into air pouches established in BALB/c mice. Histological and molecular analyses were performed with inflammatory tissue samples obtained from mice treated with and without enalapril.

Results

Enalapril inhibited tissue inflammation and inflammatory osteolysis induced by Ti particles, reducing pouch membrane thickness and decreasing inflammatory cell infiltration. In addition, enalapril inhibited the expression of the inflammatory cytokines vascular endothelial growth factor and tumor necrosis factor-α.

Conclusions

Our study provides evidence that enalapril inhibits Ti particle-induced inflammatory osteolysis, and it may be a potentially useful treatment for aseptic loosening.

3D printing-assisted fabrication of patient-specific antibacterial radial head prosthesis with high periprosthetic bone preservation

We present a novel fabrication and surgical approach for anatomical reconstruction of a fractured radial head using patient-specific radial head prosthesis made of polymethylmethacrylate (PMMA) bone cement. To this end, the use of PMMA bone cement for prosthesis fabrication was initially investigated using computational modeling and experimental methods. The radial head prosthesis was fabricated through casting of PMMA bone cement in silicone mold in the operation room before implantation. To enhance the precision of bony preparation for replacement of the radial head, patient-specific surgical guide for accurate resection of the radial neck with the desired length was developed. Post-surgical clinical examinations revealed biomechanical restoration of elbow function, owing to the use of patient-specific radial head prosthesis and surgical guide. Importantly, follow-up radiographs after a mean follow-up of 18 months revealed bone preservation at the bone-prosthesis interface without any signs of erosion of the capitellum. Taken together, our method demonstrated the safety and efficacy of the PMMA radial head prosthesis in restoring elbow biomechanics. This also provides a very safe and cost-effective method for making various patient-specific prostheses with localized antibacterial delivery and close mechanical properties to native bone for improved periprosthetic bone regeneration.

Bone cement as a local chemotherapeutic drug delivery carrier in orthopedic oncology: A review

Metastatic bone lesions are common among patients with advanced cancers. While chemotherapy and radiotherapy may be prescribed immediately after diagnosis, the majority of severe metastatic bone lesions are treated by reconstructive surgery, which, in some cases, is followed by postoperative radiotherapy or chemotherapy. However, despite recent advancements in orthopedic surgery, patients undergoing reconstruction still have the risk of developing severe complications such as tumor recurrence and reconstruction failure. This has led to the introduction and evaluation of poly (methyl methacrylate) and inorganic bone cements as local carriers for chemotherapeutic drugs (usually, antineoplastic drugs (ANPDs)). The present work is a critical review of the literature on the potential use of these cements in orthopedic oncology. While several studies have demonstrated the benefits of providing high local drug concentrations while minimizing systemic side effects, only six studies have been conducted to assess the local toxic effect of these drug-loaded cements and they all reported negative effects on healthy bone structure. These findings do not close the door on chemotherapeutic bone cements; rather, they should assist in materials selection when designing future materials for the treatment of metastatic bone disease.

Netrin-1 regulates ERK1/2 signaling pathway and autophagy activation in wear particle-induced osteoclastogenesis

Background

Artificial joint replacement surgery is often accompanied by osteolysis induced aseptic loosening around the prosthesis. Wear particles from joint replacement are thought to be one of the main factors leading to local inflammation and osteolysis at the prosthesis site. The aim of this study was to investigate the molecular mechanism of osteoclast formation and dissolution induced by wear particles and the potential roles of Netrin‐1, the ERK1/2 pathway and autophagy activation in this process.

Methods

The messenger RNA levels in cells and tissues were detected with real‐time quantitative PCR. The western blotting was used to detect the expression of proteins. A CCK‐8 kit was used to detect the viability of RAW 264.7 cells. Moreover, an air pouch model of bone resorption was established. Immunohistochemistry was used to detect the expression of TRAP and Netrin‐1 in rat bone tissue. Cell culture supernatants were collected in the rat air pouch model of bone resorption, and the levels of RANKL and OPG were detected with enzyme‐linked immunosorbent assay. The protein levels of TRAP and Netrin‐1 in bone tissue were examined by immunohistochemistry.

Results

Titanium wear particles induced osteoclast formation and autophagy activation. Moreover, blocking autophagy suppressed the osteoclastogenesis after exposure to wear particles in vitro. The activation of the ERK1/2 pathway and the overexpression of Netrin‐1 were both found to play important roles in osteoclastogenesis mediated by autophagy. Moreover, 3‐MA effectively decreased the secretion of proinflammatory cytokines mediated by wear particles.

Conclusion

Blockade of autophagy inhibits the osteoclastogenesis and inflammation induced by wear particles, thus potentially providing novel treatment strategies for abnormal osteoclastogenesis and aseptic prosthesis loosening induced by wear particles.

The Effect of Inflammation on Bone

Bone remodeling is the continual process to renew the adult skeleton through the sequential action of osteoblasts and osteoclasts. Nuclear factor RANK, an osteoclast receptor, and its ligand RANKL, expressed on the surface of osteoblasts, result in coordinated control of bone remodeling. Inflammation, a feature of illness and injury, plays a distinct role in skewing this process toward resorption. It does so via the interaction of inflammatory mediators and their related peptides with osteoblasts and osteoclasts, as well as other immune cells, to alter the expression of RANK and RANKL. Such chemical mediators include TNFα, glucocorticoids, histamine, bradykinin, PGE2, systemic RANKL from immune cells, and interleukins 1 and 6. Conditions, such as periodontal disease and alveolar bone erosion, aseptic prosthetic loosening, rheumatoid arthritis, and some sports related injuries are characterized by the result of this process. A thorough understanding of bone response to injury and disease, and ability to detect such biomarkers, as well as imaging to identify early structural and mechanical property changes in bone architecture, is important in improving management and outcomes of bone related pathology. While gut health and vitamin and mineral availability appear vitally important, nutraceuticals also have an impact on bone health. To date most pharmaceutical intervention targets inflammatory cytokines, although strategies to favorably alter inflammation induced bone pathology are currently limited. Further research is required in this field to advance early detection and treatments.

Effect of Physiological Saline Solution Contamination on Selected Mechanical Properties of Seasoned Acrylic Bone Cements of Medium and High Viscosity

Bone cements play a key role in present-day surgery, including the implantation of hip and knee joint endoprostheses. The correct and durable bonding of the prosthesis to the bone is affected by both the static strength characteristics determined in accordance with ISO 5833:2002 and the resistance to long-term exposure to an aggressive environment of the human body and the impurities that may be introduced into the cement during implementation. The study attempts to demonstrate statistically significant degradation of cement as a result of the seasoning of cement samples in Ringer’s solution with simultaneous contamination of the material with saline solution, which is usually present in the surgical field (e.g., during the fixing of endoprostheses). The results of statistical analysis showed the nature of changes in compressive strength and microhardness due to seasoning time and degree of contamination.

Osteoclast-mediated biocorrosion of pure titanium in an inflammatory microenvironment

Titanium (Ti) and alloys thereof are commonly utilized in biomedical settings owing to their desirable mechanical properties and good biocompatibility. However, when exposed to biological systems for extended periods of time, Ti still undergoes corrosion. In the present study, we therefore explore the impact of osteoclasts (OC) on the surface characteristics and corrosion of commercially pure Titanium (cpTi) in the context of lipopolysaccharide (LPS)-induced inflammation. We utilized tartrate resistant acidic phosphatase (TRAP) and fluorescence staining to assess OC properties, while scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), optical profilometer, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization tests, and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used to evaluate metal microstructure, surface composition and roughness, electrochemical corrosion properties, and metal ion release. SEM findings demonstrated that the surface of cpTi exhibited micro-pitting as well as the presence of viable OCs. Correspondingly, cpTi that had been exposed to OCs exhibited reduced levels of Ti, oxygen, and oxides within the corroded regions relative to smooth Ti as measured via EDS and XPS. OC exposure was also associated with significant changes in cpTi surface roughness, a significant decrease in corrosion resistance, and a significant increase in the release of Ti ions into the surrounding medium. In summary, these findings indicate that OC culture on the surface of cpTi can directly corrode titanium and lead to the release of Ti ions.

Enhanced expression of coxsackievirus and adenovirus receptor in lipopolysaccharide-induced inflammatory macrophages is through TRIF-dependent innate immunity pathway

AIMS

Inflammatory macrophages have been proposed as a therapeutic target for joint disorders caused by inflammation. This study aimed to investigate the expression and regulation of coxsackievirus-adenovirus receptor (CAR) in lipopolysaccharide (LPS)-stimulated inflammatory macrophages whereby to evaluate the feasibility of virus-directed enzyme prodrug therapy (VDEPT).

MAIN METHODS

Macrophage cell lines (RAW264.7 and J774A.1) and primary macrophage cells derived from rat spleen were used to evaluate the expression of CAR protein or CAR mRNA. Specific inhibitors for TLR4 pathway were used to investigate the regulation of CAR expression. CAR expression in rat joints was documented by immunohistochemistry. Conditionally replicating adenovirus, CRAd-EGFP(PS1217L) or CRAd-NTR(PS1217H6), and non-replicating adenovirus CTL102 were used to transduce genes for enhanced green fluorescent protein (EGFP) or nitroreductase (NTR), respectively. The expression of EGFP, NTR, and the toxicity induced by CB1954 activation were evaluated.

KEY FINDINGS

The in vitro experiments revealed that CAR upregulation was mediated through the TLR4/TRIF/IRF3 pathway in LPS-stimulated inflammatory macrophage RAW264.7 and J774A.1 cells. The inflammatory RAW264.7 cells upregulated CAR expression following LPS stimulation, leading to higher infectability, increased NTR expression, and enhanced sensitization to CB1954. In animal experiments, the induction of CAR expression was observed in the CD68-expressing primary macrophages and in the CD68-expressing macrophages within joints following LPS stimulation.

SIGNIFICANCE

In conclusion, we report an enhanced CAR expression in inflammatory macrophages in vitro and in vivo through the immune response elicited by LPS. Thus, the TLR4/TRIF/IRF3 pathway of macrophages, when activated, could facilitate the therapeutic application of adenovirus-mediated VDEPT.

Nepetin inhibits osteoclastogenesis by inhibiting RANKL-induced activation of NF-κB and MAPK signalling pathway, and autophagy

Aseptic prosthetic loosening due to wear particle-induced inflammatory osteolysis is the main cause of failure for artificial joint replacement. The inflammatory response and the production of pro-osteoclastic factors lead to elevation of osteoclast formation and excessive activity results in extensive bone destruction around the bone-implant interface. Here we showed that Nepetin, a natural bioactive flavonoid with proven anti-inflammatory and anti-proliferative properties, potently inhibited RANKL-induced osteoclast differentiation, formation and bone resorption in vitro, and protected mice against the deleterious effects of titanium particle-induced calvarial osteolysis in vivo. Mechanistically, Nepetin attenuated RANKL-induced activation of NF-κB and MAPK signalling pathways and TRAF6-dependent ubiquitination of Beclin 1 which is necessary for the induction of autophagy. In brief, our study demonstrates the potential therapeutic application of Nepetin against osteoclast-mediated osteolytic diseases.

The gut microbiota may be a novel pathogenic mechanism in loosening of orthopedic implants in rats

Particles released from implants cause inflammatory bone loss, which is a key factor in aseptic loosening, the most common reason for joint replacement failure. With the anticipated increased incidence of total joint replacement in the next decade, implant failure will continue to burden patients. The gut microbiome is increasingly recognized as an important factor in bone physiology, however, its role in implant loosening is currently unknown. We tested the hypothesis that implant loosening is associated with changes in the gut microbiota in a preclinical model. When the particle challenge caused local joint inflammation, decreased peri-implant bone volume, and decreased implant fixation, the gut microbiota was affected. When the particle challenge did not cause this triad of local effects, the gut microbiota was not affected. Our results suggest that cross-talk between these compartments is a previously unrecognized mechanism of failure following total joint replacement.

A Modified Murine Calvarial Osteolysis Model Exposed to Ti Particles in Aseptic Loosening

Aim

To investigate the different effects on osteolysis between commercial pure Ti particles and TiAl6V4 particles obtained from prosthesis of patients with aseptic loosening.

Method

Scanning electron microscope, energy dispersive X-ray spectrometry, and X-ray diffraction were used for the size test, chemical composition test, and phase analysis of two kinds of Ti particles. Microcomputed tomography (micro-CT) and 3-dimensional reconstruction analysis were applied to analyze the bone loss quantitatively and radiologically. Hematoxylin-eosin (HE) staining and tartrate-resistant acid phosphatase (TRAP) staining were used to assess the histologic difference.

Result

TiAl6V4 particles were constituted by FeO, Al₄₅V₇, and Al₃Ti while pure Ti particles were constituted by Ti, Ti₃O, and C₄H₇NO₃. Similar particle size of nanoscale was detected of two Ti particles. A TiAl6V4 osteolysis model had more severe bone loss when scanned with micro-CT and assessed by quantitative analysis. TiAl6V4 also presented deeper and wider calvarial bone loss in HE staining and more activated osteoclasts in TRAP staining.

Conclusion

A mouse calvarial model is the most effective animal model for the primary in vivo research of aseptic loosening. Compared with commercial Ti particles, TiAl6V4 particles derived from prosthesis of an aseptic loosening patient had more severe bone loss and more activated osteoclast, which was more consistent with pathogenesis of aseptic loosening in vivo, had high success rate of establishment of a model, and was more desired in animal modeling.

A multifaceted biomimetic interface to improve the longevity of orthopedic implants

The rise of additive manufacturing has provided a paradigm shift in the fabrication of precise, patient-specific implants that replicate the physical properties of native bone. However, eliciting an optimal biological response from such materials for rapid bone integration remains a challenge. Here we propose for the first time a one-step ion-assisted plasma polymerization process to create bio-functional 3D printed titanium (Ti) implants that offer rapid bone integration. Using selective laser melting, porous Ti implants with enhanced bone-mimicking mechanical properties were fabricated. The implants were functionalized uniformly with a highly reactive, radical-rich polymeric coating generated using a unique combination of plasma polymerization and plasma immersion ion implantation. We demonstrated the performance of such activated Ti implants with a focus on the coating's homogeneity, stability, and biological functionality. It was shown that the optimized coating was highly robust and possessed superb physico-chemical stability in a corrosive physiological solution. The plasma activated coating was cytocompatible and non-immunogenic; and through its high reactivity, it allowed for easy, one-step covalent immobilization of functional biomolecules in the absence of solvents or chemicals. The activated Ti implants bio-functionalized with bone morphogenetic protein 2 (BMP-2) showed a reduced protein desorption and a more sustained osteoblast response both in vitro and in vivo compared to implants modified through conventional physisorption of BMP-2. The versatile new approach presented here will enable the development of bio-functionalized additively manufactured implants that are patient-specific and offer improved integration with host tissue. STATEMENT OF SIGNIFICANCE: Additive manufacturing has revolutionized the fabrication of patient-specific orthopedic implants. Although such 3D printed implants can show desirable mechanical and mass transport properties, they often require surface bio-functionalities to enable control over the biological response. Surface covalent immobilization of bioactive molecules is a viable approach to achieve this. Here we report the development of additively manufactured titanium implants that precisely replicate the physical properties of native bone and are bio-functionalized in a simple, reagent-free step. Our results show that covalent attachment of bone-related growth factors through ion-assisted plasma polymerized interlayers circumvents their desorption in physiological solution and significantly improves the bone induction by the implants both in vitro and in vivo.

A 3D-Printed Ultra-Low Young's Modulus β-Ti Alloy for Biomedical Applications

The metastable β-Ti21S alloy is evaluated as a potential candidate for biomedical parts. Near fully dense (99.75 ± 0.02%) samples are additively manufactured (that is, 3D-printed) by laser powder-bed fusion (L-PBF). In the as-built condition, the material consists of metastable β-phase only, with columnar grains oriented along the building direction. The material exhibits an extremely low Young’s modulus (52 ± 0.3 GPa), which was never reported for this type of alloy. The combination of good mechanical strength (σ_y0.2 = 709 ± 6 MPa, ultimate tensile strength (UTS) = 831 ± 3 MPa) and high total elongation during tensile test (21% ± 1.2%) in the as-built state, that is, without any heat treatment, is close to that of the wrought alloy and comparable to that of heat treated Ti grade 5. The good biocompatibility attested by cytotoxicity tests confirms its great suitability for biomedical applications.

Self-healing biomaterials: The next generation is nano

The U.S. Agency for Healthcare Research and Quality estimates that there are over 1 million total hip and total knee replacements each year in the U.S. alone. Twenty five percent of those implants will experience aseptic loosening, and bone cement failure is an important part of this. Bone cements are based on poly(methyl methacrylate) (PMMA) systems that are strong but brittle polymers. PMMA-based materials are also essential to modern dental fillings, and likewise, the failure rates are high with lifetimes of 3-10 years. These brittle polymers are an obvious target for self-healing systems which could reduce revision surgeries and visits to dentist. Self-healing polymers have been described in the literature since 1996 and examples from Roman times are known, but their application in medicine has been challenging. This review looks at the development of self-healing biomaterials for these applications and the challenges that lie between development and the clinic. Many of the most promising formulations involve introducing nanoscale components which offer substantial potential benefits over their microscale counterparts especially in composite systems. There is substantial promise for translation, but issues with toxicity, robustness, and reproducibility of these materials in the complex environment of the body must be addressed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanomaterials and Implants.