Critical-sized bone defects can result from trauma, inflammation, and tumor resection. Such bone defects, often have irregular shapes, resulting in the need for new technologies to produce suitable implants. Bioprinting is an additive manufacturing method to create complex and individualised bone constructs, which can already include vital cells. In this study, we established an extrusion-based printing technology to produce osteoinductive scaffolds based on polycaprolactone (PCL) combined with calcium phosphate, which is known to induce osteogenic differentiation of stem cells. The model was created in python based on the signed distance functions. The shape of the 3D model is a ring with a diameter of 20 mm and a height of 10 mm with a spongiosa-like structure. The interconnected irregular pores have a diameter of 2 mm +/− 0.2 mm standard deviation. Extrusion-based printing was performed using the BIO X6. To produce the bioink, PCL (80 kDa) was combined with calcium phosphate nanopowder (> 150 nm particle size) under heating. After printing, 5 × 10. 6. hMSC were seeded on the construct using a rotating incubator. We were able to print a highly accurate ring construct with an interconnected pore structure. The PCL combined with calcium phosphate particles resulted in a precise printed construct, which corresponded to the 3D model. The bioink containing calcium phosphate nanoparticles had a higher printing accuracy compared to PCL alone. We found that hMSC cultured on the construct settled in close proximity to the calcium phosphate particles. The hMSC were vital for 22 days on the construct as demonstrated by life/dead staining. The extrusion printing technology enables to print a mechanically stable construct with a spongiosa-like structure. The porous PCL ring could serve as an outer matrix for implants, providing the construct the stability of natural bone. To extend this technology and to improve the implant properties, a biologised inner structure will be integrated into the scaffold in the future

Aims: to develop a fast biomimetic method to deposit nanocrystalline calcium phosphate coatings on titanium substrates. Methods: Ti6Al4V disks (diameter = 15mm) were ultrasonically cleaned with acetone, ethanol and demineralized water, and then etched in a mixture of HF and HNO3. The disks were soaked in a supersaturated Ca/P solution at 37A1C, pH 7.2 for different periods of time up to 3 days. The structure and morphology of the obtained coatings were characterized using thin film X-ray diffraction, SEM and TEM investigation. Furthermore, coated and uncoated diskes were soaked in simulated body fluid (SBF) for different periods of time. Results: the first calcium phosphate deposits on the etched Ti6Al4V disks can be appreciated after 7 days of soaking in SBF solution. At variance, soaking of the Ti6Al4V disks in the supersaturated Ca/P solution, with a simpler composition than that of SBF, yields the deposition of a uniform calcium phosphate coating in a few hours. Thin film X-ray diffraction patterns show that the coating is constituted of a poor crystalline apatitic phase, and that the extent of deposition increases on increasing the soaking time in the supersaturated solution. TEM images recorded on the material detached from the coating by ultrasound vibration show that the apatitic deposition is constituted of thin nanocrystals. The results obtained on coated substrates submitted to interaction with SBF indicate that the presence of the coating reduces the time required to appreciate the deposition of apatite from SBF to just 24 hours. Conclusions: the method utilized in this work can be successfully applied to obtain fast deposition of uniform coatings of nanocrystalline hydroxyapatite on titanium substrates

The recent development and use of Calcium Phosphate (CaP) based products as orthopaedic implants has increased the need for the development of a greater understanding of the starting materials inherent properties. Chemical composition and crystal phase greatly influence the final product’s behaviour in the body. By gaining a deeper understanding of these properties, greater control in making tailor-made products can be achieved. Calcium Phosphate based powders of varying CaO: P2O5 ratios were prepared by cold isostatic pressing into compact discs (13 mm diameter x 3.6 mm height) and subsequently sintered at temperatures ranging between 200 to 1140 degrees Celsius for a period of 8 hours. The starting powders had CaO:P2O5 ratios ranging from 1.165 to 1.22. Each composition was analysed for microstructural and associated crystal phase modifications with varying sintering temperatures, by scanning electron microscopy (SEM) and X-ray diffraction (XRD). All compositions were shown by XRD to have an initial starting composition of Hydroxyapatite (HA) and Dicalcium Phosphate Anhydrous (DCPA). With increasing sintering temperatures, it was found that the initial composition readily transformed to beta-tricalcium phosphate(B-TCP) for all of the CaO:P2O5 ratios. However, it was found that the higher CaO:P2O5 ratio materials tended to retain residual HA. Sintering of all powders was found to have a densification effect on the microstructure of these compositions. The sintering behaviour of calcium phosphates is extremely dependent on the CaO:P2O5 ratio of the material, influencing both the crystal as well as microstructural properties of the sintered components. This in-turn will have a strong influence on the behaviour of this biomaterial when placed in-vivo

Summary Statement. Calcium phosphate (CaP) particles have attracted great interest as transfection reagents, yet little is known about their mechanism of internalisation. We report live cell time-course tracking of CaP particles during internalisation and the influence of Ca:P ratio on transfection efficiency. Introduction. Relatively recent work has seen calcium phosphate (CaP) salts used for the delivery of biological materials into cells in the form of peptides, polymers and DNA sequences. Calcium phosphate salts have a critical safety advantage over other vectors such as viruses in that they pose no risk of pathogenicity due to mutation and show no apparent cytotoxicity. Previous work within the group showed that Ca:P ratio influenced the transfection efficiency, but the fate of the particles on internalisation is yet unknown. The difficulty in tracking the particles can be related to the visual similarity to granulation within the cells. Using a surface modification method that enables the fluorescent labeling of silicon-substituted hydroxyapatite (SiHA) particles, we have tracked the internalisation of the particles to understand their mechanism of entry and how particle composition may influence transfection efficiency. Patients & Methods. SiHA particles were synthesised by the dropwise addition of an aqueous solution of diammonium hydrogen phosphate and silicon tetraacetate to an aqueous solution of calcium nitrate while under mixing and maintained at pH10. The particles were functionalised with thiol groups using (3-mercaptopropyl)trimethoxysilane and dye-labelled with fluorescein-5-maleimide. MC3T3 osteoblast precursor cells were incubated in cell culture media containing labelled particles at a concentration of 0.6μg/mL for 12 hours. Confocal images were obtained with a Zeiss LSM 710 ConfoCor 3 system based around a Zeiss AxioObserverZ1 microscope. Results. DNA binding efficiency between 79 to 94%, the lowest being the CaP sample of new CaP route at Ca/P ratio of 0.33 by SEDS processing, which was 79% and the highest was the HAp SEDS processed sample at 40°C, solvent flowrate of 1 ml/min and antisolvent flowrate of 60 g/min (particle size of 131 nm). From the fluorescence microscopy images, localised regions of particles measuring around 500–1000nm were detected. With a typical SiHA particle size of 50–70nm in length, these regions contain 10's of particles. Discussion/Conclusion. Thiol functionalisation enabled the internalised SiHA to be visually discriminated from the other cellular material with similar morphology and optical contrast as shown in the bright field image. HA particles (Ca:P of 1.67) showed a strong affinity for the cell membrane despite extensive washing with PBS and their higher calcium content may enhance the binding of the DNA to the particle surface, therefore improving transfection efficiency

Introduction: Incorporation of Silicon into the HA structure enhances the bioactivity of Hydroxyapatite (HA). Silicon substituted calcium phosphate (SiCaP/SiHA) has been introduced as an osteoconductive material for bone formation. However, the osseoinductive capacity of this biomaterial has not been assessed. A previous study by Hing et al shows that bioactivity of stoichiometric hydroxyapatite bone substitute materials is enhanced by increasing the level of porosity within the implant struts [1]. The aim of this study was to test the hypothesis that SiCaP bone graft results in superior osseoinduction compared to stoichiometric HA and osseoinduction enhancement using high microporosity materials. Methods: Implantation of 32 bone graft plugs (16 granular and 16 blocks) with 3 different strut porosities: 20% SiHA, 35% SiHA, 10% SiHA and 20% HA, all with matched 80% total porosity supplied by ApaTech Ltd into the paraspinalis muscle of 4 sheep for 12 weeks. HA and %SiHA locations were randomized at implant sites. Following euthanasia at 12 weeks histomorphometry was carried out to calculate Percentage of bone, soft tissue and implant area and Percentage of the amount of bone in contact with the calcium phosphate surface (% Bone attachment). Further evaluation of Calcium, Phosphate and Silicon levels within the implants and surrounding bone was carried out by Scanning Electron Microscopy (SEM) and EDAX. Results: Bone formation was observed within the pores of both granules and blocks of SiCaP and HA implants. Greater bone formation and attachment was detected in scaffolds with higher strut porosity (SiHA35) compared to implants of the same chemical composition but lower strut porosity (SiHA10, SiHA20. More bone formation and contact was observed in SiHA implants (SiHA20) compared to matched porosity HA implants where the amount of bone formed was minimal. Uniform distribution of Silicon (Si) was visible within the SiHA scaffold struts according to EDAX results. Greater quantities of Si existed in newly formed bone as compared to soft tissue adjacent to the SiHA implants. Silicon was not detected in either soft or hard tissues adjacent to HA implants. Conclusion: Both microporous HA and SiCaP promote bone ingrowth, as ectopic bone formation was observed in all four groups of synthetic materials. Matched porosity SiCaP is more osseoinductive than HA. Increasing strut porosity results in promotion of osseoinductivity. High strut porosity (> 10%) block environment contributes to greater osseoinductive behaviour. In conclusion we report that presence of silicon and the strut porosity influence the osseoinductive capacity of calcium phosphate bone substitute biomaterials

Treatment of bone infection often includes a burdensome two-stage revision. After debridement, contaminated implants are removed and replaced with a non-absorbable cement spacer loaded with antibiotics. Weeks later, the spacer is exchanged with a bone graft aiding bone healing. However, even with this two-stage approach infection persists. In this study, we investigated whether a novel 3D-printed, antibiotic-loaded, osteoinductive calcium phosphate scaffold (CPS) is effective in single-stage revision of an infected non-union with segmental bone loss in rabbits. A 5 mm defect was created in the radius of female New Zealand White rabbits. The bone fragment was replaced, stabilized with cerclage wire and inoculated with Staphylococcus aureus (MSSA). After 4 weeks, the infected bone fragment was removed, the site debrided and a spacer implanted. Depending on group allocation, rabbits received: 1) PMMA spacer with gentamycin; 2) CPS loaded with rifampin and vancomycin and 3) Non-loaded CPS. These groups received systemic cefazolin for 4 weeks after revision. Group 4 received a loaded CPS without any adjunctive systemic therapy (n=12 group1-3, n=11 group 4). All animals were euthanized 8 weeks after revision and assessed by quantitative bacteriology or histology. Covariance analysis (ANCOVA) and multiple regression were performed. All animals were culture positive at revision surgery. Half of the animals in all groups had eliminated the infection by end of study. In a historical control group with empty defect and no systemic antibiotic treatment, all animals were infected at euthanasia. There was no significant difference in CFU counts between groups at euthanasia. Our results show that treating an osteomyelitis with segmental bone loss either with CPS or PMMA has a similar cure rate of infection. However, by not requiring a second surgery, the use of CPS may offer advantages over non-resorbable equivalents such as PMMA

Aims: The study we present compares quantitatively the bone regeneration in experimental animals obtained with autologus and homologus grafts against a calcium phosphate cement. Methods: We performed cavitary defects o 6 mm of diameter in the metaphiseal region of the distal femur of 48 rabbits of albine race. They were divided in 4 groups, and received respectively autologous grafts, homologous freezed graft, calcium phosphate cement or the absence of any implant (control group). Results: The results are valued by radiological, histological and histomorphometrical studies (with digitalysed images). Histological study shows a correct integration of the calcium phosphate cement, without þbrous interphase, and a bone regeneration which is progressive and centripetal. Statistical analysis of the histomorphometrical data shows that bone regeneration obtained with the calcium phosphate cement its similar to the one obtained with the grafts. Conclusions: Calcium phosphate cement is a biocompatible material, biodegradable and conductor

Introduction: Filling bone defects with Polymethylmetaacrylate (PMMA) has been a easy, safe and reliable technique for past four decade. Newly developed Calcium Phosphate Paste (CPP) is a mixture of alpfa Tri Calcium Phsphate (TCP), Tetra Calcium Phosphate, Calcium Hydrogen Phosphate and Hydroxyapatite. This paste hardens in 10 minutes and its stffness increases to 80Mpa in seven days. It generates no heat, no gas and requires no organic solvents. In process of hardening, the TCP structure changes to Hydroxyapatite. Materials and methods: We have used CPP in two TKA cases associate with bone defect, and 14 fracture cases. In a MRSA infected revision TKA case, reconstruction was performed with PMMA-VCM articulated spacers, and they was fixed to bone with CPP-VCM. MRSA infection has been well controlled and weight bearing could be done in 10 days after surgery. In another TKA case, large bone necrosis in femoral condyle was filled with CPP and Cementless inplant were placed on it. Seven days later, this patient could walk with a cane. Results: CPP filled in bones were not absorbed for a year, and exess CPP in soft tissue were absorbed in several weeks. In 16 cases no side effects were observed during as long as one year. Conclusion: Handling CPP is much easier than Hydroxyapatite brick or granule. CPP can be useful for total joint arthroplasty, especially in large bone defect or infected cases. It can replace a part of PMMA as a bone cement for implants in the near future

The fixation of titanium or titanium alloy implants is related to their surface composition and topography. Osteoconductive calcium phosphate coatings promote bone healing and apposition, leading to the rapid biological fixation of implants. It’s no doubt that the addition of certain biologically active protein with biomaterial will improve the bioactivity of the material. Previously, we examined the biocompatibility of basic fibroblast growth factor (bFGF) incorporation with titanium implants. Now we investigate the effect of fibronectin (FN) incorporation with thin calcium phosphate film deposited on titanium by electron-beam evaporation since fibronectin is actively involved in cell adhesion, spreading, would healing, cytoskeletal reorganization, and bone tissue formation. A FN-apatite composite layer was formed on the surface of titanium by biomimetic process. The coating process was carried out by immersing thin calcium phosphate film coated Ti in Dulbecco’s Phosphate buffered saline containing FN (20 ug/ml). The surfaces of samples were examined with FESEM, Fourier transform infrared spectroscopy and X-ray diffraction. The quantity of FN taken up and the kinetics of protein release were monitored by BCA method and Elisa. The fibronectin was immobilized in the newly formed apatite layer. The adhesion of osteoblast cells to the FN-apatite composite layer was to show the biocompatibility of implants, and FN-apatite composite layer could enhance osseintegration of implants in vivo. This research was supported by a grant (code #: 08K1501-01220) from Center for Nanostructured Materials Technology under 21st Century Frontier R& D Program of the Ministry of Education, Science and Technology, Korea

Purpose: Filling bone loss during revision total hip arthroplasty raises many problems related both to the surgical technique and to the type of bone substitute used. The purpose of this study was to report the clinical and radiographic results obtained in a series of femur reconstructions using impacted calcium phosphate ceramics. Material and methods: The technique used here was derived from the method developed for impacted fragmentary grafts by Ling and Gie. Grains of macroporous biphasic calcium phosphate ceramic (MBCP) were impacted into the femoral shaft to obtain a stable sheath into which the stem could be cemented (Ceraver Osteal). This technique was used from March 1996 to october 2000 in 18 patients (20 hips) undergoing revision for femoral loosening in 11 (including septic loosening in eight), femoral osteolysis (one hip), pain (one hip), and instability (one hip). Mean age ate revision was 66 years (range 30–79). Most of the femoral bone defects were classed grade IV. The grains of MBCP were used alone in 13 cases, in a mixture with allografts in five cases, and in a mixture with autologous bone in two cases. Results: Mean follow-up was 31 months (range 8–70). None of the patients were lost to follow-up. There were two intraoperative femur shaft fractures which healed without sequela. Two patients required a second revision for loosening (including one septic) 20 and 16 months after the first revision. At last follow-up, the mean PMA score had improved to 16 (12–18) (p< 0.05) and 67% of the patients achieved a good or excellent clinical result. Radiologically, there were 14 cases of good osteointegration of the MBCP grains without implant migration. Mean shortening was 3 mm (3–5) was observed in three cases and a stable incomplete lucent line was observed in one patient with no clinical impact. Discussion: Calcium phosphate ceramic material can be useful to overcome the problem of major bone loss in RTHA. It provides an attractive alternative to the disadvantages of bone grafting and helps, in theory, improve primary implant stability. The original technique presented here has allowed us to achieve promising short-term results in young patients with an adequate femur

A carbonated apatite cement with a high compressive strength was used in the treatment of tibial plateau fractures. There were 41 patients (20 male; 21 female; mean age 59 years). All patients had isolated tibial plateau fractures. There were 15 B2.2, 23 B3.1 and 3 B2.3 fractures. Fractures were fixed with limited internal fixation using a short anterior parapatellar incision. Reduction and fixation were initially achieved. Once this was carried out the void under the elevated plateau was filled using calcium phosphate cement. A buttress plate was used in one case, screws or K-wires in 33 cases and calcium phosphate cement alone in 7 cases. Patients were mobilised partially weight bearing in a hinged knee brace and allowed full weight bearing at 6 weeks. Reductions were anatomic (< 2mm displacement in 32 (78%) cases, satisfactory (3-5mm displacement) in 7 (17%) cases and imperfect (> 5mm) in 2 (5%) patients. Extrusion of some calcium phosphate cement into surrounding soft tissue occurred in one case. This material resorbed with no adverse effects. Loss of reduction was observed in 6 (15%) cases. There were no other significant complications. Thirty-seven patients (90%) had more than 120 degrees of knee flexion at 6 months. Calcium phosphate cement is an alternative to the use of bone grafting in any area of cancellous subject to compressive load. It is ideal for use in tibial plateau fractures with compressed subchondral bone after elevation. It obviates the need for buttress plating and bone grafting and there is no bone graft donor site morbidity. Patients are able to mobilise more rapidly and early discharge is facilitated. Calcium phosphate cement is a promising development in the management of tibial plateau fractures and initial results suggest it may be more effective in maintaining reduction that standard methods of fixation and grafting

Tibial opening wedge osteotomy is still a worthwhile surgical procedure in the treatment of tibial varus deformity to prevent knee arthritis. However, it requires a long period without weight-bearing because of the need of bone harvesting substitution at the osteotomy site. The authors present their experience with endoscopic injection of Norian SRS calcium phosphate cement to speed patient recovery and to avoid any potential in soft tissue complications. From January 2001 the authors performed 13 tibial opening wedge osteotomy in 12 patients. All the patients previously underwent to a knee arthroscopy. The average age was 51 years (range 35–56). In all cases the injection of Norian SRS calcium phosphate cement was controlled arthroscopically and the fixation was maintained with a Puddu’s plate. The patients were assessed using the GIUM Score, pre-operatively and at the latest follow-up. The authors did not register any problems due to the Norian SRS calcium phosphate cement. Total weight-bearing was allowed after an average of 26 days. Radiographically the bone substitute appeared well integrated at the latest follow-up. Pre-operatively the mean GIUM score was 56.1 (range 36–68). At the latest follow-up the mean GIUM score was 94.2 (range 84–98). All the patients were satisfied and had returned to their previous occupation. The authors suggest Norian SRS calcium phosphate cement to speed patientrecovery after tibial opening wedge osteotomy

Summary Statement. The present study demonstrates the beneficial effects of strontium (Sr) modified calcium phosphate cement to improve new bone formation in a metaphyseal osteoporotic fracture defects in rats compared to calcium phosphate cement and empty defects. Keywords: strontium, fracture, calcium phosphate, bone formation. Introduction. Impaired fracture healing with subsequent implant failure is a dramatic problem in osteoporotic fractures. Biomaterials are of interest to stimulate fracture healing in osteoporotic defects and the objective of the current study is to investigate the effects of Strontium modified calcium phosphate cement (SrCPC) in a critical-size metaphyseal fracture defect of osteoporotic rats compared to calcium phosphate (CPC) and empty defect control group. Methods. 45 female Sprague-Dawley rats were randomized into 3 groups: SrCPC, CPC and empty defect (n=15 for each). A combinatorial approach of multi-deficiency diet for 3 months after bilateral ovariectomy was used for induction of osteoporosis. Left femur of all animals underwent a 4mm wedge-shaped metaphyseal osteotomy that was internally fixed with a T-shaped plate. The defect was then either filled with CPC or SrCPC and internally stabilised with a T shaped mini-plate. Empty defect served as a control. After 6 weeks femora were harvested followed by histological, histomorphometrical, immunohistochemical (bone-morphogenic protein 2, osteocalcin and osteoprotegerin), and molecular biology analysis (alkaline phosphatase, collagen10a1 and osteocalcin) to demonstrate the effects of the biomaterials on new bone formation. Time of flight secondary ion mass spectrometry (TOF-SIMS) technology was used to assess the distribution of released strontium ions and calcium appearance of newly formed bone. Results. Histomorphometric analysis showed a statistically significant increase in the bone formation at the tissue-implant interface in the SrCPC group (p<0.001). A statistically significantly more cartilage and unmineralised bone formation was also seen in the SrCPC group in comparision to the CPC group alone (p<0.05) and also to the empty defect (p<0.05) in the former fracture defect zone. These data were confirmed by the immunohistochemistry results which revealed an increase in bone-morphogenic protein 2, osteocalcin and osteoprotegerin and an increase in expression of genes responsible for bone formation viz. alkaline phosphatase, collagen10a1 and osteocalcin. TOF-SIMs analysis showed a higher release of Sr from the SrCPC into the interface region and related to a higher calcium content in this area compared to CPC. Discussion/Conclusion. SrCPC treatment showed enhanced new bone formation in a metaphyseal osteoporotic fracture defect of rats after 6 weeks compared to CPC-filled and empty defects in histomorphometry, immunochemistry and gene expression analysis. Strontium ranelate is a well-known anti-osteoporotic drug increasing bone formation and reducing bone resorption. As revealed by TOF-SIMS release of Sr out of the the SrCPC cement is most likely attributable for new bone formation. Therefore, Sr seems to be a good candidate not only for systemic treatment in osteoporosis but also in Sr-modification of biomaterials for local stimulation of new bone formation in osteoporotic fracture defects

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

Introduction: Joint replacement procedures such as revision impaction grafting and spinal fusion interbody operations are stretching allograft bone stocks to their limits. The need for synthetic alternatives that offer a structural and biological matrix for graft incorporation are paramount for future bone regeneration procedures. Synthetic bone graft alternatives that offer biocompatibility to the host bone (i.e. a biological response) such as hydroxyapatite/tricalcium phosphate (HA/TCP), in addition to possessing an interconnected porosity network have been shown to have a strong influence on the osteoinductive potential of these materials. The current method allows the production of calcium phosphate ceramic components (CPC) that possess an interconnected open porous network in the required size range for osteoid growth and revascularisation. Materials and Methods: The method can be described as the reticulated foam technique, whereby two grades of calcium phosphate powder are blended together to form a HA/TCP ceramic slip. The slip is then ball milled for 24hrs with zirconia milling media. This slip is used to impregnate polyurethane (PU) foam via a mechanical plunging procedure. The impregnated foam is then held above the slip bath in order for the slip to flow and coat the struts of the foam. The impregnated foam is then dried on tissue paper and treated with high velocity compressed air to avoid the formation of any closed cells. Samples are dried at 120°C for 15hrs. The PU foams are graded as 30 and 45ppi (pores per inch). The slip viscosity ranges from 6000 – 8000 cps (measured with a Brookfield Viscometer, spindle no. 5 and at 10rpm). Samples are sintered slowly until 600°C to ensure PU burnout is complete. Sintering continues up to 1280°C to ensure densification. Image analysis was performed using optical microscopy, digital photography and SEM analysis. Mechanical testing was performed by 3 point bending using an 1122 Instron. Results: Macroporosity in the samples varied from 40 – 70%. Typical pore sizes far exceeded 300μm (the pore size acknowledged as that needed for osteogenesis). Approx. 79% of all pores were between 150 – 450μm in area equivalent diameter. Typical strut thicknesses ranging from 100 – 500μm were also reported, as was a strut thickness-pore size-mechanical strength relationship. One hundred and twenty samples possessed a breaking stress with a 95% confidence level of 0.30MPa±0.01MPa. The low strengths reported are due to the formation of blow-out holes at triple point junctions on the interconnected struts. Conclusions: Major requirements for replacement bone materials have been met including a wide range of interconnected porosity from 50 – 1000μm. Bioactivity combined with an excellent porosity size range suggests excellent possibility of osteogenesis. In addition, this fabrication procedure offers consistency and reliability. Future work will focus on improving the strength of these open porous calcium phosphate ceramics

Background. Due to their tailored porous texture, breathability and flexibility, carbon cloths (CCs) are good scaffolds for biomedical application. However, biocompatibility of CCs depends on their physic-chemical properties. Calcium phosphate ceramics (CaP) are well known for their use in orthopaedic field. So, carbon cloth-reinforced CaP composites are promising bioceramic materials for bone regeneration. Methods. CaP coating are performed using sono-electrochemical deposition method. The electrolyte consisted in an aqueous solution of calcium and phosphates precursors. CC was used as work electrode in three-electrode system. SEM, TEM, XRD, 1H and 31P MAS NMR and FTIR spectroscopies were performed to characterise the deposits. In vitro biocompatibility of CCs with and without coatings is tested with human osteoblasts. Results. The current density influences the morphology and the chemical composition of deposit: it consists mainly in carbonated hydroxyapatite with plate-like shape for lower current densities and needle-like shape for the highest. A hydrophobic surface of CC with due to small amount of oxygenated functions leads to a poor biocompatibility. Conclusion. The wettability of CCs is an important parameter of biocompatibility. Biomimetic CaP deposits obtained by sono-electrodeposition present a microstructure and a chemical composition close to the mineral phase of natural bone. This work was supported by Region Centre project: bioactive hybrid materials for bone reconstruction. 2014–2016

Summary Statement. Repetitive concavities threaded on the surface of bone implants have been already demonstrated to be effective on ectopic bone formation in vivo. The aim of this study was to investigate the effect of concavity on the mineralization process in vitro. Introduction. The role of implant surface geometry in bone formation has been extensively investigated. Ripamonti and co. investigated the possibility to induce bone formation by threading concavities on the surface of calcium phosphate implants, without the need for exogenous osteogenic soluble factors. The underlying hypothesis was that this geometry, by resembling the hemi-osteon trench observable during osteoclastogenesis, was able to activate the ripple-like cascade of bone tissue induction and morphogenesis. Despite several studies indicating a positive effect of concavities on bone induction, so far no attempts have rationalised this phenomenon by means of in vitro tests. Consequently, this study aimed to evaluate the effect of surface concavities on the mineralization of hydroxyapatite (HA) and beta-tricalciumphosphate (b-TCP) ceramics in vitro. Our hypothesis was that concavities could effectively guide the mineralization process in vitro. Materials and Methods. Different-size concavities were threaded into the surface of HA and b-TCP semi-sintered disks: 1.8 (large concavity, LC), 0.8 (medium concavity, MC) and 0.4 mm (small concavity, SC). Disks were fully sintered at 1200 or 1100 °C and soaked in simulated body fluid (SBF) up to 28 days. Distinct experiments were carried out in order to assess the role of chemical composition, sintering temperature and concavity size on the extent of mineralization in vitro. The mineralization process was followed by SEM, EDS, XRD and Ca assay tests. Results and Discussion. Massive mineralization occurred exclusively at the surface of the HA disks treated at 1200 °C. Firstly, aggregates of spherical-like amorphous calcium phosphate nucleated specifically within concavities and not on the planar surface. At a later stage, a flake-like apatitic phase replaced the spherical-like apatite and spread out the concavities until covering the entire disk surface. Instead, a lower extent of mineralization occurred on HA disk treated at 1100 °C, with no formation of flake-like phase. In contrast, no significative mineralization was observed for b-TCP disks, irrespective of sintering temperature. Finally, the extent of mineralization on disks exhibiting SC on the surface was found to be about 120- and 10-fold higher than mineralization disks threaded with LC and MC, respectively. Conclusions. The main results of this study are: i) the in vitro mineralization process of CaP ceramics with surface concavities starts preferentially within the concavities and not on the planar surface; ii) concavity size is an extremely effective parameter for controlling the extent of mineralization in vitro. Finally, the results reported in this study suggest correlation between the positive effect of concavities on mineralization in vitro and on ectopic bone formation in vivo

The purpose of this study was to review the outcomes of patients treated with injectable calcium phosphate cement (Norian SRS, Norian Corporation, Cupertino, California) for contained bone defects after resection of benign or low-grade malignant bone tumours. The clinical records and radiographs of 17 patients who had been treated with calcium phosphate cement were reviewed, looking for incorporation into bone, reabsorption of the material and complications. The 17 patients had a mean age of 29.8 years (range 7 to 64). The diagnosis was giant cell tumour in 9 cases, fibrous dyplasia in 2, low grade chondrosarcoma in 2, and one each of enchondroma, chondromyxoid fibroma, osteofibrous dysplasia, and chondroblastoma. The tibia was involved in 9 cases, the femur in 6 and the radius in 2. The mean follow up was 11 months (range 3 to 25). The material is radioopaque and well visualised on plain radiographs. In most cases, incorporation of the material into the bone structure appeared good, but there was little absorption of the material during the followup available. The exceptions were 2 cases in which the material was absorbed following local recurrence of giant cell tumour. One fracture associated with a giant cell tumour healed well in the presence of the material. In three patients, there were clinical and radiological features at follow up suggestive of periostitis related to the material. In one case a florid effusion of the knee may have been due to the material. Injectable calcium phosphate cement may have a role in the management of contained defects requiring mechanical support following resection of benign or low-grade malignant tumours of bone. However, problems with periostitis, possibly synovitis and absorption in the presence of local recurrence should be considered

Miniscrew implants (MSIs) are widely used to provide absolute anchorage for the orthodontic treatment. However, the application of MSIs is limited by the relatively high failure rate (22.86%). In this study, we wished to investigate the effects of amorphous and crystalline biomimetic calcium phosphate coating on the surfaces of MSIs with or without the incorporated BSA for the osteointegration process with an aim to facilitate the early loading of MSIs. Amorphous and crystalline coatings were prepared on titanium mini-pin implants. Characterizations of coatings were examined by Scanning electron microscopy (SEM), Confocal laser-scanning dual-channel-fluorescence microscopy (CLSM) and Fourier-transform infrared spectroscopy (FTIR). The loading and release kinetics of bovine serum albumin (BSA) were evaluated by Enzyme linked immunosorbent assay (ELISA). Activity of alkaline phosphate (ALP) was measured by using the primary osteoblasts. In vivo, a model of metaphyseal tibial implantation in rats was used (n=6 rats per group). We had 6 different groups: no coating no BSA, no coating but with surface adsorption of BSA and incorporation of BSA in the biomimetic coating in the amorphous and crystalline coatings. Time points were 3 days, 1, 2 and 4 weeks. Histological and histomorphometric analysis were performed and the bone to implant contact (BIC) of each group was compared. In vitro, the incorporation of BSA changed the crystalline coating from sharp plates into curly plates, and the crystalline coating showed slow-release profile. The incorporation of BSA in crystalline coating significantly decreased the activity of ALP in vitro. In vivo study, the earliest significant increase of BIC appeared in crystalline coating group at one week. The crystalline coating can serve as a carrier and slow release system for the bioactive agent and accelerate osteoconductivity at early stage in vivo. The presence of BSA is not favorable for the early establishment of osteointegration

Introduction. Osteoporotic intertrochanteric fracture (ITF) is frequent injuries affecting elderly, osteoporotic patients leading to significant morbidity and mortality. Successful prognosis including union and alignment is challenging even though initial successful reduction with internal fixation. Although many factors are related to the patient's final prognosis. Well reduction with stable fracture fixation is still the goal of treatment to improve the quality of life and decrease morbidity in patients with hip fractures, but this in turn depends on the type of fracture and bone quality. Poor bone quality is responsible for common complications, such as failure of fixation, varus collapse and lag screw cut-out, in elderly patients. Kim et al. found that the complication rate when using conventional DHS in unstable ITFs can be as high as 50% because of screw cut-out. We used the dynamic hip screws (DHS) strengthened by calcium phosphate cement (CPC) for treatment femoral intertrochanteric fracture and review the prognosis of our patients. Materials and Methods. From January of 2011 to January of 2014, 42 patients with femoral intertrochanteric fracture underwent surgery with DHS strengthened by CPC. Comparisons were made between the DHS plus CPC group with the other patients with only DHS used in our department. All patients were followed up for an average time of 14.8(6 to 24) months. X-ray was reviewed for the conditions of union and implant failure. Results. In DHS group, fixation failure happened in 3 case, delayed union and coax varus deformity in 2 cases. IN DHS plus CPC group, all fractures healed uneventfully, there is no non-union or malunion in this group. There is only 1 fixation cut-out and 1 secondary lag screw sliding was noted, however, union was still well over fracture site in this case, the patient had no clinical symptoms. Discussion. Residual bony defects present after DHS fixation in intertrochanteric fracture may lead to postoperative complications, including nonunion or implant failure. DHS strengthened by CPC is reliable fixation for old patients with intertrochanteric fracture, We demonstrated that augmentation of the bony defect with dynamic hip screw by reinforced calcium phosphate cement significantly improved the strength of osteoporotic bone, prevent screw loosening, and promote early healing of fracture. The patients can be decreased the risk of refracture and allow early weight bearing, especially in elderly patients with osteoporotic bone