Objectives. The surface of pure titanium (Ti) shows decreased histocompatibility over time; this phenomenon is known as biological ageing. UV irradiation enables the reversal of biological ageing through photofunctionalisation, a physicochemical alteration of the titanium surface. Ti implants are sterilised by UV irradiation in dental surgery. However, orthopaedic biomaterials are usually composed of the alloy Ti6Al4V, for which the antibacterial effects of UV irradiation are unconfirmed. Here we evaluated the bactericidal and antimicrobial effects of treating Ti and Ti6Al4V with UV irradiation of a lower and briefer dose than previously reported, for applications in implant surgery. Materials and Methods. Ti and Ti6Al4V disks were prepared. To evaluate the bactericidal effect of UV irradiation, Staphylococcus aureus 834 suspension was seeded onto the disks, which were then exposed to UV light for 15 minutes at a dose of 9 J/cm. 2. To evaluate the antimicrobial activity of UV irradiation, bacterial suspensions were seeded onto the disks 0, 0.5, one, six, 24 and 48 hours, and three and seven days after UV irradiation as described above. In both experiments, the bacteria were then harvested, cultured, and the number of colonies were counted. Results. No colonies were observed when UV irradiation was performed after the bacteria were added to the disks. When the bacteria were seeded after UV irradiation, the amount of surviving bacteria on the Ti and Ti6Al4V disks decreased at 0 hours and then gradually increased. However, the antimicrobial activity was maintained for seven days after UV irradiation. Conclusion. Antimicrobial activity was induced for seven days after UV irradiation on both types of disk. Irradiated Ti6Al4V and Ti had similar antimicrobial properties. Cite this article: T. Itabashi, K. Narita, A. Ono, K. Wada, T. Tanaka, G. Kumagai, R. Yamauchi, A. Nakane, Y. Ishibashi. Bactericidal and antimicrobial effects of pure titanium and titanium alloy treated with short-term, low-energy UV irradiation. Bone Joint Res 2017;6:108–112. DOI: 10.1302/2046-3758.62.2000619

The success of long-term transcutaneous implants depends on dermal attachment to prevent downgrowth of the epithelium and infection. Hydroxyapatite (HA) coatings and fibronectin (Fn) have independently been shown to regulate fibroblast activity and improve attachment. In an attempt to enhance this phenomenon we adsorbed Fn onto HA-coated substrates. Our study was designed to test the hypothesis that adsorption of Fn onto HA produces a surface that will increase the attachment of dermal fibroblasts better than HA alone or titanium alloy controls. . Iodinated Fn was used to investigate the durability of the protein coating and a bioassay using human dermal fibroblasts was performed to assess the effects of the coating on cell attachment. Cell attachment data were compared with those for HA alone and titanium alloy controls at one, four and 24 hours. Protein attachment peaked within one hour of incubation and the maximum binding efficiency was achieved with an initial droplet of 1000 ng. We showed that after 24 hours one-fifth of the initial Fn coating remained on the substrates, and this resulted in a significant, three-, four-, and sevenfold increase in dermal fibroblast attachment strength compared to uncoated controls at one, four and 24 hours, respectively

Aim. To control the growth and function of osteoblasts on Titanium alloy surfaces produced by electrochemical patterning. Methods. Samples of Ti6Al4V were prepared with three different finishes; no surface preparation following machining, polishing on a grinding wheel with sequential grit papers up to 4000 to achieve a mirror finish and treatment in a flat electrochemical cell with a 3M sulphuric acid in methanol using 9V supplied over 60 seconds to produce a surface with defined nano/microscale roughness. Glass coverslips were used as control surfaces. Surfaces were seeded with primary rat calvarial osteoblasts and incubated in Dulbecco's Modified Eagle Medium with 10% (v/v) sera for 24 hours before fixing and performing immunofluorescence staining with anti-vinculin antibody. Photomicrographs of the surfaces were analysed with Image J and analySIS FIVE programs. Results for cell number, cell area, focal adhesion area and polarity (lack of roundness) were analysed (using the Mann Whitney test) for ANOVA using SPSS. Results. Cells adhered to all surfaces with the most cells on the polished surface and the fewest on the glass and 9V60s surfaces. There were significant differences in cell number only between the polished surface and the glass control (p=0.026) and the 9V60s surface (p=0.006). Cells grown on the glass control surfaces exhibited the largest areas (mean = 840micron2) whilst those on the machined surface were the smallest (mean = 601micron2). A significant difference in cell area was seen between the machined and polished surfaces (p=0.025). The area of the focal adhesions was significantly different between the cells on 9V60s surface and the glass control (p=0.004), machined (p=0.003) and polished surfaces (p=0.006). Significant differences in polarity were seen between the cells on machined surface and the glass control (p=0.004), polished (p=0.004) and 9V60s surfaces (p=0.004). Discussion. Differences in cell numbers on glass and two of the Ti surfaces may be explained by the smooth nature of the glass coverslips in comparison to the nanoscale topography on the polished and 9V60s treated surfaces. Cell area was noted to be different between the machined and smoother polished surface. This may be explained by the grooves present on the machined surfaces preventing normal cell spreading by the process of contact guidance. There was a marked difference in polarity between the most polarised cells on the machined surface and the more rounded cells on the smoother surfaces, again consistent with the behaviour of contact guidance, with cells growing in the direction of the surface grooves. Focal adhesions present on the 9V60s treated surface were very small in comparison to those on other surfaces. Several features of implant surfaces may affect osteoblast growth, including surface roughness, chemical composition, surface charge and surface energy. These features influence the adsorption of proteins onto the surfaces, in turn influencing the growth and behaviour of the adherent cell population. Conclusion. Mechanical and electrochemical treatment of titanium alloy can significantly affect the growth and behaviour of osteoblasts grown on the surface. This has potential applications in arthroplasty and fracture fixation

Our aim was to determine whether in vitro studies would detect differences in the cellular response to wear particles of two titanium alloys commonly used in the manufacture of joint replacement prostheses. Particles were of the order of 1 μm in diameter representative of those found adjacent to failed prostheses. Exposure of human monocytes to titanium 6-aluminium 4- vanadium (TiAlV) at concentrations of 4 x 10. 7. particles/ml produced a mean prostaglandin E. 2. release of 2627.6 pM; this was significantly higher than the 317.4 pM induced by titanium 6-aluminium 7-niobium alloy (TiAlNb) particles (p = 0.006). Commercially-pure titanium particles induced a release of 347.8 pM. In addition, TiAlV stimulated significantly more release of the other cell mediators, interleukin-1, tumour necrosis factor and interleukin-6. At lower concentrations of particles there was less mediator release and less obvious differences between materials. None of the materials caused significant toxicity. The levels of inflammatory mediators released by phagocytic cells in response to wear particles may influence the amount of periprosthetic bone loss. Our findings have shown that in vitro studies can detect differences in cellular response induced by particles of similar titanium alloys in common clinical use, although in vivo studies have shown little difference. While in vitro studies should not be used as the only form of assessment, they must be considered when assessing the relative biocompatibility of different implant materials

Objectives. Ultraviolet (UV) light-mediated photofunctionalisation is known to improve osseointegration of pure titanium (Ti). However, histological examination of titanium alloy (Ti6Al4V), which is frequently applied in orthopaedic and dental surgery, has not yet been performed. This study examined the osseointegration of photofunctionalised Ti6Al4V implants. Methods. Ti and Ti6Al4V implants were treated with UV light, and the chemical composition and contact angle on the surfaces were evaluated to confirm photofunctionalisation. The implants were inserted into femurs in rats, and the rats were killed two or four weeks after the surgery. For histomorphometric analysis, both the bone–implant contact (BIC) ratio and the bone volume (BV) ratio were calculated from histological analysis and microcomputed tomography data. Results. The amount of carbon and the contact angle on both implants were significantly reduced after UV irradiation. The BIC ratios for both UV light-treated implants significantly increased at two weeks, but there was no significant difference at four weeks. There was no significant difference in the BV ratios between the UV light-treated and control implants at two or four weeks. Conclusions. This study suggests that photofunctionalisation of Ti6Al4V implants, similar to that of Ti implants, may promotes osseointegration in early but not in the late phase of osseointegration. Cite this article: R. Yamauchi, T. Itabashi, K. Wada, T. Tanaka, G. Kumagai, Y. Ishibashi. Photofunctionalised Ti6Al4V implants enhance early phase osseointegration. Bone Joint Res 2017;6:331–336. DOI: 10.1302/2046-3758.65.BJR-2016-0221.R1

Particulate wear debris is associated with periprosthetic inflammation and loosening in total joint arthroplasty. We tested the effects of titanium alloy (Ti-alloy) and PMMA particles on monocyte/macrophage expression of the C-C chemokines, monocyte chemoattractant protein-1 (MCP-1), monocyte inflammatory protein-1 alpha (MIP-1α), and regulated upon activation normal T expressed and secreted protein (RANTES). Periprosthetic granulomatous tissue was analysed for expression of macrophage chemokines by immunohistochemistry. Chemokine expression in human monocytes/macrophages exposed to Ti-alloy and PMMA particles in vitro was determined by RT-PCR, ELISA and monocyte migration. We observed MCP-1 and MIP-1α expression in all tissue samples from failed arthroplasties. Ti-alloy and PMMA particles increased expression of MCP-1 and MIP-1α in macrophages in vitro in a dose- and time-dependent manner whereas RANTES was not detected. mRNA signal levels for MCP-1 and MIP-1α were also observed in cells after exposure to particles. Monocyte migration was stimulated by culture medium collected from macrophages exposed to Ti-alloy and PMMA particles. Antibodies to MCP-1 and MIP-1α inhibited chemotactic activity of the culture medium samples. Release of C-C chemokines by macrophages in response to wear particles may contribute to chronic inflammation at the bone-implant interface in total joint arthroplasty

Prosthetic joint infections (PJI) occur infrequently, but they represent the most devastating complication with high morbidity and substantial cost. Staphylococcus aureus and coagulase-negative S. epidermidis are the most commonly infecting agents associated with PJI. Nowadays, Gram-negative species like Escherichia coli and Pseudomonas aeruginosa are gaining relevance.

The use of TiO2 conical nanotubular doped with fluorine and phosphorous (FP-cNT) surfaces is an interesting approach to prevent surface bacterial colonization during surgery and favouring the osseointegration. Despite of there are serum markers related with PJI, to date there is described no biomaterial-related marker that allows detecting PJI. Here we describe the adherence and the bactericidal effect of FP-cNT and its capacity of marking the non-fermenting bacteria that have been in contact with it by Al. This metal is delivered by FP-cNT in non-toxic concentrations (between 25 and 29 ng/mL).

F-P-cNT layers on Ti6Al4V alloy were produced as described previously by our group. Ti6Al4V chemical polishing (CP) samples without nanostructure were used as control and produced as described previously.

S. aureus 15981, S. epidermidis ATCC 35984, E. coli ATCC 25922, and P. aeruginosa ATCC 27853 strains adherence study was performed using the protocol described by Kinnari et al. in 0.9% NaCl sterile saline with a 120 min incubation. After incubation, the samples were stained with LIVE/DEAD BacLight Bacterial Viability Kit. Proportion of live and dead bacteria was calculated and studied by using ImageJ software. The experiments were performed in triplicate. The aluminum concentration was estimated in the supernatant after incubation and in the 0.22 µm filtered supernatant by atomic absorption in graphite furnace.

The statistical data were analyzed by nonparametric Kruskal-Walis test and by pairwise comparisons using the nonparametric unilateral Wilcoxon test with a level of statistical significance of p<0.05. The values are cited as medians.

Our results show that the bacterial adherence of all tested species significantly decreased on FP-cNT compared to CP except P. aeruginosa ATCC 27853: 19.8% for S. aureus 15981, 45.3% for S. epidermidis ATCC 35984 and 8.1% for E. coli ATCC 25922. The bacterial viability decreased 2-fold for S. aureus 15981, and 5-fold for S. epidemidis ATCC 35984, but increased 95% for P. aeruginosa ATCC 27853 and there no was variation for E. coli ATCC 25922 on FP-cNT compared to CP. Only supernatant P. aeruginosa ATCC 27853 shows significant Al detection after 120 min incubation (p<0.05).

In summary, F-P cNT is a promising biomaterial that besides favoring osseointegration and potential usefulness as drug carrier, present bactericidal, non-stick ability (at least for staphylococci and E. coli) and is able to mark P. aeruginosa with Al, which could be potentially monitored in serum and urine in patients with PJI.

We have examined 26 retrieved, failed titanium-alloy femoral stems. The clinical details, radiological appearances and the histology of the surrounding soft tissues in each patient were also investigated.

The stems were predominantly of the flanged design and had a characteristic pattern of wear. A review of the radiographs showed a series of changes, progressive with time. The first was lateral debonding with subsidence of the stem. This was followed by calcar resorption and fragmentation or fracture of the cement. Finally, osteolysis was seen, starting with a radiolucency at the cement-bone interface and progressing to endosteal cavitation.

Three histological appearances were noted: granulomatous, necrobiotic and necrotic. We suggest that an unknown factor, possibly related to the design of the stem, caused it to move early. After this, micromovement at the cement-stem interface led to the generation of particulate debris and fracture of the cement. A soft-tissue reaction to the debris resulted in osteolysis and failure of fixation of the prostheses.

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

Abstract. Objectives. Additive manufacturing has led to numerous innovations in orthopaedic surgery: surgical guides; surface coatings/textures; and custom implants. Most contemporary implants are made from titanium alloy (Ti-6Al-4V). Despite being widely available industrially and clinically, there is little published information on the performance of this 3D printed material for orthopaedic devices with respect to regulatory approval. The aim of this study was to document the mechanical, chemical and biological properties of selective laser sintering (SLS) manufactured specimens following medical device (TOKA®, 3D Metal Printing LTD, UK) submission and review by the UK Medicines and Healthcare Products Regulatory Agency (MHRA). Methods. All specimens were additively manufactured in Ti-6Al-4V ELI (Renishaw plc, UK). Mechanical tests were performed according to ISO6892-1, ISO9585 and ISO12107 for tensile (n=10), bending (n=3) and fatigue (n=16) respectively (University of Bath, UK). Appropriate chemical characterisation and biological tests were selected according to recommendations in ISO10993 and conducted by external laboratories (Wickham Labs, UK; Lucideon, UK; Edwards Analytical, UK) in adherence with Good Lab Practise guidelines. A toxicological review was conducted on the findings (Bibra, UK). Results. The mechanical tests demonstrated that the material performed to the specification for conventionally manufactured titanium alloy of this type (ISO5832-3). The toxicology review concluded that there were no significant concerns for the health of the patients identified in this evaluation and implantation of the TOKA® device would not result in a significant health risk to patients. Conclusions. Reflecting on our MHRA experience, additive manufacture of orthopaedic devices is still considered to be a ‘novel’ process by regulatory bodies, requiring additional safety evidence. Despite this, our findings demonstrate that there is no difference, mechanically or chemically, to the traditionally manufactured alloy material. We hope to support the widening use of 3D printed titanium alloy orthopaedic devices by publishing our route to regulatory approval. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

AM specifically allows for cost-efficient production of patient-specific Orthopaedic medical devices with unusual designs and properties. A porous design allows to adjust the stiffness of metallic implants to that of the host bone. Beyond traditional metals, like titanium alloys, this talk will review the present state-of-the-art of directly printed absorbable metal families. Physicochemical, mechanical and biological properties of standardized design prototypes from all currently available metal families will be compared and their clinical application potential discussed. The impact of in vitro test environments on comparative corrosion behavior, post manufacturing aspects, and the recent status quo in biocompatibility testing and present knowledge gaps will be addressed

Intramedullary nails (IMNs) are the current gold standard for treatment of long bone diaphyseal and selected metaphyseal fractures. Their design has undergone many revisions to improve fixation techniques, conform to the bone shape with appropriate anatomic fit, reduce operative time and radiation exposure, and extend the indication of the same implant for treatment of different fracture types with minimal soft tissue irritation. The IMNs are made or either titanium alloy or stainless steel and work as load-sharing internal splints along the long bone, usually accommodating locking elements – screws and blades, often featuring angular stability and offering different configurations for multiplanar fixation – to secure secondary fracture healing with callus formation in a relative-stability environment. Bone cement augmentation of the locking elements can modulate the construct stiffness, increase the surface area at the bone-implant interface, and prevent cut-through of the locking elements. The functional requirements of IMNs are related to maintaining fracture reduction in terms of length, alignment and rotation to enhance fracture healing. The load distribution during patient's activities is along the entire bone-nail interface, with nail length and anatomic fit being important factors to avoid stress risers

Infection in orthopedics is a challenge, since it has high incidence (rates can be up to 15-20%, also depending on the surgical procedure and on comorbidities), interferes with osseointegration and brings severe complications to the patients and high societal burden. In particular, infection rates are high in oncologic surgery, when biomedical devices are used to fill bone gaps created to remove tumors. To increase osseointegration, calcium phosphates coatings are used. To prevent infection, metal- and mainly silver-based coatings are the most diffused option. However, traditional techniques present some drawbacks, including scarce adhesion to the substrate, detachments, and/or poor control over metal ions release, all leading to cytotoxicity and/or interfering with osteointegration. Since important cross-relations exist among infection, osseointegration and tumors, solutions capable of addressing all would be a breakthrough innovation in the field and could improve clinical practice. Here, for the first time, we propose the use antimicrobial silver-based nanostructured thin films to simultaneously discourage infection and bone metastases. Coatings are obtained by Ionized Jet Deposition, a plasma-assisted technique that permits to manufacture films of submicrometric thickness having a nanostructured surface texture. These characteristics, in turn, allow tuning silver release and avoid delamination, thus preventing toxicity. In addition, to mitigate interference with osseointegration, here silver composites with bone apatite are explored. Indeed, capability of bone apatite coatings to promote osseointegration had been previously demonstrated in vitro and in vivo. Here, antibacterial efficacy and biocompatibility of silver-based films are tested in vitro and in vivo. Finally, for the first time, a proof-of-concept of antitumor efficacy of the silver-based films is shown in vitro. Coatings are obtained by silver and silver-bone apatite composite targets. Both standard and custom-made (porous) vertebral titanium alloy prostheses are used as substrates. Films composition and morphology depending on the deposition parameters are investigated and optimized. Antibacterial efficacy of silver films is tested in vitro against gram+ and gram- species (E. coli, P. aeruginosa, S. aureus, E. faecalis), to determine the optimal coatings characteristics, by assessing reduction of bacterial viability, adhesion to substrate and biofilm formation. Biocompatibility is tested in vitro on fibroblasts and MSCs and, in vivo on rat models. Efficacy is also tested in an in vivo rabbit model, using a multidrug resistant strain of S. aureus (MRSA, S. aureus USA 300). Absence of nanotoxicity is assessed in vivo by measuring possible presence of Ag in the blood or in target organs (ICP-MS). Then, possible antitumor effect of the films is preliminary assessed in vitro using MDA-MB-231 cells, live/dead assay and scanning electron microscopy (FEG-SEM). Statistical analysis is performed and data are reported as Mean ± standard Deviation at a significance level of p <0.05. Silver and silver-bone apatite films show high efficacy in vitro against all the tested strains (complete inhibition of planktonic growth, reduction of biofilm formation > 50%), without causing cytotoxicity. Biocompatibility is also confirmed in vivo. In vivo, Ag and Ag-bone apatite films can inhibit the MRSA strain (>99% and >86% reduction against ctr, respectively). Residual antibacterial activity is retained after explant (at 1 month). These studies indicate that IJD films are highly tunable and can be a promising route to overcome the main challenges in orthopedic prostheses

Orthopedic metallic medical devices are essential in the treatment of a wide range of skeletal diseases and disabilities. However, they are often related with surgery complications due to acute prosthetic joint infections (PJI) causing devastating complications. Gallium (Ga) antibacterial activity has been recently demonstrated: in aqueous solutions, Ga ionize in a trivalent form Ga. 3+. that can replace Fe. 3+. in bacterial metabolism thus leading to bacteria death. However, it is not yet clear whether such effect is typical to Ga. 3+. release, and how this would affect longer term performance. Here we investigated Ga addition into titanium alloys using metallurgical methods. The study has confirmed that metallurgical addition of gallium even in small amounts (1–2% wt.) to titanium alloys have highly efficient antibacterial function without any visible cytostatic or cytotoxic effects. The presence of gallium within the metal matrix might ensure that antibacterial effect will persist for a long time towards multi-drug resistant S. aureus, which might not be possible if gallium or other metal are only in thin degradable coatings or similar formulations. A 5-logs decrease in CFU number was detected for alloys with 2% Ga and more after 72 h (alamar blue and CFU count assays). The alloys also show to be in vitro cytocompatible with both mature U2OS osteoblasts and progenitor pre-osteoblasts hFOB. Since gallium is metallurgically analogous to aluminium in titanium alloys, it might be used without affecting other alloy properties

Introduction and Objective. The surgical strategy for acetabular component revision is determined by available host bone stock. Acetabular bone deficiencies vary from cavitary or segmental defects to complete discontinuity. For segmental acetabular defects with more than 50% of the graft supporting the cup it is recommended the application of reinforcement ring or ilioischial antiprotrusio devices. Acetabular reconstruction with the use of the antiprotrusion cage (APC) and allografts represents a reliable procedure to manage severe periprosthetic deficiencies with highly successful long-term outcomes in revision arthroplasty. Objective. We present our experience, results, critical issues and technical innovations aimed at improving survival rates of antiprotrusio cages. Materials and Methods. From 2004 to 2019 we performed 69 revisions of the acetabulum using defrosted morcellized bone graft and the Burch Schneider anti-protrusion cage. The approach was direct lateral in 25 cases, direct anterior in 44. Patients were re-evaluated with standard radiography and clinical examination. Results. Eight patients died from causes not related to surgery, and two patients were not available for follow up. Five patients were reviewed for, respectively, non-osseointegration of the ring, post-traumatic loosening with rupture of the screws preceded by the appearance of supero-medial radiolucency, post-traumatic rupture of the distal flange, post-traumatic rupture of the cemented polyethylene-ceramic insert, and dislocation treated with new dual-mobility insert. Among these cases, the first three did not show macroscopic signs of osseointegration of the ring, and the only areas of stability were represented by the bone-cement contact at the holes in the ring. Although radiographic studies have shown fast remodeling of the bone graft and the implant survival range from 70% to 100% in the 10-year follow up, the actual osseointegration of the ring has yet to be clarified. To improve osseointegration of the currently available APC whose metal surface in contact with the bone is sandblasted, we combined the main features of the APC design long validated by surgical experience with the 3D-Metal Technology for high porosity of the external surface already applied to and validated with the press fit cups. The new APC design is produced with the 3D-Metal technology using Titanium alloy (Ti6Al4V ELI) that Improves fatigue resistance, primary stability and favorable environment for bone graft ingrowth. We preview the results of the first cases with short-term follow up. Conclusions. Acetabular reconstruction with impacted morcellized bone graft and APC is a current and reliable surgical technique that allows the restoration of bone loss with a high survival rate of the implant in the medium to long term. The new 3D Metal Cage is designed to offer high friction for the initial stability. The high porosity of the 3D Metal structure creates a favorable environment for bone growth, thus providing valid secondary fixation reproducing the results achieved with the 3D metal press fit cup

Abstract. Objectives. Additive manufacturing (AM) enables fine control over the architecture of porous lattice structures, and the resulting mechanical performance. Orthopaedic implants may benefit from the tailored stiffness/elastic modulus of these AM biomaterials, as the stiffness can be made to closer match the properties of the replaced trabecular bone. Methods. This study used laser powder bed fusion (PBF) to create stochastic porous lattice structures in stainless steel (SS316L) and titanium alloy (Ti6Al4V), with modifications that aimed to overcome PBF manufacturing limitations of build angles. The structures were tested in uni-axial compression (n = 5) in 10 load orientations relative to the structure, including the three orthogonal axes. Results. The testing verified that no hidden peaks in elastic modulus existed in the stochastic structure. The standard deviation of the 10 elastic modulus values in the final structure decreased from 249 MPa to 101 MPa when made in SS316L and from 95.9 MPa to 52.5 MPa for Ti6Al4V, indicating the structures were more isotropic. Conclusions. These modified stochastic lattices have similar stiffness to cancellous bone and have controllable anisotropy, giving them the potential to be used within implants which match the stiffness of trabecular bone. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction and Objective. The choice of appropriate characteristics is crucial to favor a firm bonding between orthopedic implants and the host bone and to permit bone regeneration. In particular, the morphology and composition of the biointerface plays a crucial role in orchestrating precise cellular responses. Here, to modulate the biointerface, we propose new biomimetic coatings, having multi-scale nano- to micro- morphological cues and a composition mimicking the mineral phase of bone. Materials and Methods. Films on various substrates are obtained by Ionized Jet Deposition (IJD), by ablation of biogenic apatite and annealing at 400°C for 1 hour. Films are proposed for functionalization of metallic implants, but application to heat sensitive porous (3D printed) substrates is also shown, as it permits to further boost biomimicry (by addition of collagen/gelatin), thus reproducing the architecture of cancellous bone. In IJD, coatings thickness can be selected by tuning deposition duration. Here, a 450 nm thickness is selected based on preliminary results. Micro-rough titanium alloy (Ti6Al4V) disks (roughness 5 μm) are used as a substrate for the deposition and as a control. The coatings are characterized in terms of composition (GI-XRD, EDS, FT-IR microscopy), morphology (FEG-SEM, AFM, data processing by ImageJ), mechanical properties (micro-scratch test) and dissolution profile in medium (pH 7.4, FEG-SEM). Then, their behavior is characterized in vitro (human bone marrow-derived mesenchymal stromal cells - hMSCs), by studying cells early adhesion (focal adhesion by vinculin staining), viability (Alamar Blue), morphology (SEM) and differentiation (expression of RUNX2, ALPL, SPARC and COL1A1, BMP2, BGLAP, osteocalcin, alkaline phosphatase, collagen type I) at 3, 7 and 14 days. Results. Films exhibit a biomimetic composition, as they are constituted by a nanocrystalline multi-doped carbonated hydroxyapatite. EDS indicates the presence of trace ions sodium (0,11 ± 0,02 wt%) and magnesium (0,47 ± 0,05 wt%), uniformly distributed in the coating in a percentage close to native bone. These ion-substitutions are crucial, as each ion modifies apatite solubility and ion-release in the peri-implant environment and has important biological role. Films have a high adhesion to the substrates and a suitable dissolution profile. The morphology is highly rough, as films are composed by nanosized grains (minimum diameter 40 nm) aggregated in multi-scale clusters (diameter range: 100 nm-2 μm). Morphology of the aggregates can be tuned by selecting deposition duration and also depends on the morphology, roughness and composition of the substrate. Because of the nanoscale thickness of the films, they do not alter the microscale features of the implants. For fibrous substrates, films grow onto the fibers surface, with no pore occlusion or damage to substrate composition. Coatings do not alter the metabolic activity of MSCs but influence their early adhesion, morphology and differentiation. More in detail, MSCs on coated disks show a branched shape, while those on the controls show a more spindle and elongated morphology. Coatings increase hMSCs early adhesion, as a higher density and a greater area of focal adhesions are observed at 24 hours. Finally, they can trigger a signaling pathway that promotes the osteogenic differentiation of hMSCs, as confirmed by quantification of osteocalcin, alkaline phosphatase and collagen, even in the absence of osteogenesis-inducing factors. Conclusions. The topographical and chemical cues of the biomimetic nanostructured coating are perceived by hMCSs, showing that combining morphological and biomimetic cues is a promising route for the development of cells-instructive biomaterials for orthopedics. In vivo tests on rabbit models are in progress

Introduction. A modified anodisation technique where a titanium surface releases bactericidal concentrations of silver was developed and called Agluna. Our hypothesis was that silver incorporation was bactericidal and had no effects on the viability of fibroblasts and osteoblasts, would have no negative effect on interfacial shear strength and bone contact in an in vivo trans-cortical implant ovine model. Methods. In vitro: Titanium alloy discs were either polished (Ti), anodised (Ano), anodised or Agluna treated (Ag) or anodised and Agluna treated followed by a conditioning step (Ag C). Conditioning was achieved by incubating discs in culture fluid for 48 hrs. The bactericidal effect of these discs was tested by measuring the zone of inhibition of different bacteria grown on agar. Live/dead staining was carried out and silver levels measured using atomic emission spectroscopy. 8 implants were inserted into each sheep (60 in total (n=5)). Grit blasted Titanium alloy (Gb) and Agluna treated grit blasted titanium alloy (Ag) at a silver concentration of 4-6 micrograms/cm2 were compared at 6 weeks. Gb implants, Ag (at 4-6micrograms/cm2), high dose Agluna implants with silver concentrations at 15-20micrograms/cm2 (HdAg) and a grit blasted anodised titanium alloy (Ano) were compared at 12 weeks. Pullout strength and bone-implant contact was quantified. Results. On Ti, Ano and Ag C surfaces the number of live fibroblasts was significantly greater than on Ag (non-conditioned) surfaces. Data from pull out tests at 6 weeks showed a lower but significant interfacial shear strength in the Ag group (310.4N) when compared with the Gb group (561.2N) (p=0.01). At 12 weeks, there were no significant differences between each of the 4 treatment groups. Histological analysis showed no significant differences in bone-implant contact between groups at 6 and 12 weeks. Discussion. The initial non-conditioned Agluna surface is bactericidal and cytotoxic but on conditioning, osteoblasts and fibroblasts attached and remained viable. The condition Agluna surface remains bactericidal. Silver incorporation at a concentration up to 20 micrograms/cm2 has no adverse toxic effect on osteointegration and the interfacial shear strength of implants. This coating has been used clinically in situations where the infection rate is high

Infection is the primary failure modality for transcutaneous implants because the skin breach provides a route for pathogens to enter the body. Intraosseous transcutaneous amputation prostheses (ITAP) are being developed to overcome this problem by creating a seal at the skin-implant interface to prevent bacterial invasion. Oral gingival epithelial cell adhesion creates an infection free seal around dental implants; however this has yet to be demonstrated outside the oral environment. All epithelial cells attach via hemidesmosomes (HD) and focal adhesions (FA) and their expression is an indicator of adhesion efficiency. The aim of this study was to compare epidermal keratinocyte with oral gingival epithelial cell adhesion on titanium alloy in vitro to determine whether these two cell types differ in their speed and strength of adhesion. It was hypothesised that oral gingival epithelial cells attach to titanium alloy earlier than epidermal keratinocytes; with greater expression of hemidesmosomes and focal adhesions. Human oral gingival epithelial cell (HGEP) and primary human epidermal keratinocyte (HPEK) adhesion to titanium alloy, was assessed at 4, 24, 48 and 72 hrs. Adhesion was measured by the number of FAs per unit cell area and expression of HDs using a semi-quantitative scale. At 4 and 24hrs, there was a significant increase in vinculin marker expression per unit cell area of 4.3 and 4.7 times in HGEP compared with HPEK (p=0.000). At 48 and 72hrs there were no significant differences. HD expression was significantly greater in HGEP at 4 and 24hrs (p=0.002) compared with HPEK. Up-regulation of HD expression in HPEK lagged that of HGEP until 48hrs, after which no significant differences were observed. This study has demonstrated that oral gingival cells up-regulate both focal adhesion and hemidesmosome expression at earlier time points compared with epidermal keratinocytes. Expression of hemidesmosomes lags that of focal adhesions, suggesting that focal adhesion formation is a prerequisite for hemidesmosome assembly. We postulate that early attachment of oral gingival epithelial cells to dental implant biomaterials may be responsible for the formation of an infection-free seal

Summary. Particulate wear debris with different chemical composition induced similar periprosthetic tissue reactions in patients with loosened uncemented and cemented titanium hip implants, which suggests that osteolysis can develop independent of particle composition. Introduction. Periprosthetic osteolysis is a serious long-term complication in total hip replacements (THR). Wear debris-induced inflammation is thought to be the main cause for periprosthetic bone loss and implant loosening. The aim of the present study was to compare the tissue reactions and wear debris characteristics in periprosthetic tissues from patients with failed uncemented (UC) and cemented (C) titanium alloy hip prostheses. We hypothesised that implant wear products around two different hip designs induced periprosthetic inflammation leading to osteolysis. Patients & Methods. Thirty THR-patients undergoing revision surgery were included: Fifteen patients had loose cemented titanium stems (Titan. ®. , DePuy) and 15 had well-fixed uncemented titanium stems (Profile, DePuy), but loose or worn uncemented metal-backed cups with conventional UHMWPE liners (Gemini, Tropic and Tri-Lock Plus, DePuy; Harris/Galante and Trilogy, Zimmer). A semi-quantitative histological evaluation was performed in 59 sections of periprosthetic tissues using light microscopy. Wear particles were counted by polarised light and high resolution dark-field microscopy. Additionally, particle composition was determined by SEM-EDXA following particle isolation using an enzymatic digestion method. Blood metal ions were determined with high resolution-ICP-MS. Results. The implants in the uncemented group were revised after a median of 15.7 years (range: 7.25–19.3) due to osteolysis and high wear of the polyethylene liner and metal backing resulting in gross metallosis, and/or cup loosening. The average lifetime of implants in the cemented group was only 6.5 years (range: 1.5–11.75) due to early stem loosening with large osteolysis pockets in the femur close to the cement mantle. Tissue examination revealed similar results for both groups: numerous mononuclear histiocytes and chronic inflammatory cells, a few neutrophils and multinucleated giant cells, and to some extent necrosis. The amount of metal particles per histiocyte positively correlated with the tissue reactions in the cemented, but not in the uncemented group. A higher particle load (medians: C: 14727 vs. UC: 1382 particles/mm. 2. , p<0.0001) was found in tissues adjacent to cemented stems, which contained mainly submicron ZrO. 2. particles. Particles containing pure Ti or Ti alloy elements (size range: 0.21 to 6.46 µm) were most abundant in tissues from the uncemented group. Here, also PE was more frequent, but accounted only for a small portion of total particles (2.8 PE/mm. 2. ). The blood concentrations of titanium (range: 3.8–138.5 microgram/L) and zirconium (cemented cases, range: 0.6–3.5 microgram/L) were highly elevated in cases with high abrasive wear and metallosis. Discussion/Conclusion. Phagocytosis of different wear particles by histiocytes induced a similar chronic inflammatory reaction in the periprosthetic tissues in both groups. ZrO. 2. particles, originating from bone cement degradation, dominated in the cemented group, while in the uncemented group the high abundance of pure Ti and Ti alloy particles of various sizes indicates wear of the metal-backed cups. The low density of polyethylene particles in the tissues suggests that they are not solely responsible for the tissue reactions and accompanying osteolysis. Our findings suggest that the chemical composition of wear particles plays a minor role in the mechanism of osteolysis. Particle size, load and ionic exposure might be more important