Rapid Osseointegration Research Articles

UV Photocatalysis of Bone Marrow‐Derived Macrophages on TiO2 Nanotubes Mediates Intracellular Ca2+ Influx via Voltage‐Gated Ca2+ Channels

Titanium (Ti) possesses excellent properties for use in dental implants but has low osteogenic surface properties that result in limiting rapid osseointegration. The physiological interaction between the surface of the implant material and bone cells, especially osteoclasts, is a crucial factor in determining successful osseointegration. However, the details of such an interaction remain elusive. Here, we demonstrated that nanotopography on the Ti surface is a crucial factor for modulating intracellular signal transduction in bone marrow‐derived macrophages (BMMs). To define this, intracellular Ca2+ and ROS were simultaneously measured in BMMs that were seeded on polished Ti and TiO2 nanotubes. We found that UV photocatalysis of TiO2 immediately elicits intracellular calcium concentration ([Ca2+]i) increase and intracellular reactive oxygen species concentration ([ROS]i) reduction in cells on TiO2 nanotubes. UV photocatalysis‐mediated [Ca2+]i increase is dependent on extracellular and intracellular ROS generation. Furthermore, extracellular Ca2+ influx through voltage‐gated calcium channels (VGCCs) is critical for the UV photocatalysis‐mediated [Ca2+]i increase, while phospholipase C (PLC) activation is not required. Considering the physiological roles of Ca2+ signaling in BMMs and osteoclastogenesis, nanotopography on the Ti surface should be considered an important factor that can influence successful dental implantation.

Effects of anodic titanium dioxide nanotubes of different diameters on macrophage secretion and expression of cytokines and chemokines.

To investigate effects of TiO2 nanotubes of different diameters on J744A.1 macrophage behaviour, secretion and expression of pro-inflammatory cytokines and chemokines. Macrophage-like J744A.1 cells were cultured on three types of Ti surface: mechanically polished titanium plus 30 and 80 nm TiO2 nanotube surfaces, for 4, 24 and 48 h. Macrophage adhesion and proliferation were assessed using CCK-8 assay. Levels of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and chemokines (MCP-1 and MIP-1α) secreted into the supernatant were measured using the Cytometric Bead Arrays kit. TNF-α, MCP-1 and MIP-1α gene expression were quantitatively analysed by real-time PCR. These show that TiO2 nanotube surfaces, especially of 80 nm TiO2 nanotube, benefited macrophage adhesion and proliferation, and reduced protein secretion and mRNA expression of TNF-α, MCP-1 and MIP-1α. IL-1β and IL-6 were undetectable on all the surfaces at all times. TiO2 nanotube surfaces, especially of 80 nm TiO2 nanotube, reduced inflammatory response in vitro, which might be part of a basis for rapid osseointegration in implants with TiO2 nanotube surfaces in animal studies.

Evaluation of the peri-implant bone around parallel-walled dental implants with a condensing thread macrodesign and a self-tapping apex: a 10-year retrospective histological analysis.

The long-term high percentages of survival and success of dental implants reported in the literature are related mainly to new, innovative implant and thread designs, and new implant surfaces that allow to obtain very good primary and secondary stability in most anatomical and clinical situations, even in low quality and quantity of bone, promoting a more rapid osseointegration. The aim of this retrospective study was a histological and histomorphometrical evaluation of the bone response around implants with a parallel-wall configuration, condensing thread macrodesign, and self-tapping apex, retrieved from man for different causes. A total of 10 implants were reported in the present study, and these implants had been retrieved after a loading period comprised between a few weeks to about 8 years. Mineralized newly formed bone was found at the interface of all the implants, in direct contact with the implant surface, with no gaps or connective fibrous tissue. This bone adapted very well to the microirregularities of the implant surface. Areas of bone remodeling were present in some regions of the interface, with many reversal lines. High bone-implant contact percentages were found. In conclusion, both the macrostructure and the microstructure of this specific type of implant could be very helpful in the long-term high survival and success implant percentages.

Periodontal Soft Tissue Expanders - A Review

Insufficient regeneration of missing bone and soft-tissue may present aesthetic or functional problems in patients indicative for dental implant surgery by using several techniques like bone augumentation ,bone substitutes and guided tissue regeneration.Soft tissue expansion is a technique used by plastic and restorative surgeons to cause the body to grow additional skin ,bone or the other tissues.Extensive bone augumentation procedures are frequently carried out prior to implant surgery.Preaugmentation of soft tissue expansion with expanders leads to higher functional microvessel density in the tissue above the augmentation material and thus to more rapid osseointegration and inceases the probability of success in peri-implant bone augmentation.(1)Also Extensive soft tissue mobilization is required to achieve a tension -free wound closure at the grafted site and thus avoid wound dehiscence and loss of bone graft.(2) Keywords: Complications of expansion,Osmotic hydrogel expanders,Tissue expansion,Tissue expanders.

Coaxial PCL/PVA electrospun nanofibers: osseointegration enhancer and controlled drug release device

The failure of prosthesis after total joint replacement is mainly due to dysfunctional osseointegration and implant infection. There is a critical need for orthopedic implants that promote rapid osseointegration and prevent bacterial colonization, particularly when placed in bone compromised by disease or physiology of the patients. The aim of this study was to fabricate a novel coaxial electrospun polycaprolactone (PCL)/polyvinyl alcohol (PVA) core-sheath nanofiber (NF) blended with both hydroxyapatite nanorods (HA) and type I collagen (Col) (PCLCol/PVAHA). Doxycycline (Doxy) and dexamethasone (Dex) were successfully incorporated into the PCLCol/PVAHA NFs for controlled release. The morphology, surface hydrophilicity and mechanical properties of the PCL/PVA NF mats were analyzed by scanning electron microscopy, water contact angle and atomic force microscopy. The PCLCol/PVAHA NFs are biocompatible and enhance the adhesion and proliferation of murine pre-osteoblastic MC3T3 cells. The release of Doxy and Dex from coaxial PCLCol/PVAHA NFs showed more controlled release compared with the blended NFs. Using an ex vivo porcine bone implantation model we found that the PCLCol/PVAHA NFs bind firmly on the titanium rod surface and the NFs coating remained intact on the surface of titanium rods after pullout. No disruption or delamination was observed after the pullout test. These findings indicate that PCLCol/PVAHA NFs encapsulating drugs have great potential in enhancing implant osseointegration and preventing implant infection.

Hydroxyapatite/collagen nanocomposite‐coated titanium rod for achieving rapid osseointegration onto bone surface

This article proposes less-invasive subperiosteal bone-bonding devices capable of realizing rapid osseointegration and the acquisition of fundamental knowledge required for their development. Three candidates were prepared: titanium rod specimens with a machined surface (Bare), hydroxyapatite (HAp) coating, and hydroxyapatite/collagen (HAp/Col) nanocomposite coating. To investigate bone formation around these rods, each specimen was placed under the periosteum of a male Sprague-Dawley rat calvarium. Four weeks after surgery, the samples were evaluated via histomorphometrical analyses and bonding strength tests. All the Bare specimens and more than half of the HAp specimens were encapsulated with fibrous tissue, whereas all the HAp/Col specimens were almost completely surrounded by new bone tissue without encapsulation. Histomorphometrical analyses showed that the HAp/Col group had the greatest bone contact ratio among all candidates (p < 0.05). Further, a bonding strength test indicated that the HAp/Col group exhibited the greatest bonding strength to bone (p < 0.05). Thus, HAp/Col-coated rods are considered as the best candidate materials for achieving rapid osseointegration onto a bone surface.

How bone marrow-derived human mesenchymal stem cells respond to poorly crystalline apatite coated orthopedic and dental titanium implants

Due to the delayed and weak bone-implant integration in dental and orthopedic devices, there have been several attempts to enhance implant–bone interactions for rapid osseointegration. In this paper, the interactions of human bone marrow-derived stromal (mesenchymal) stem cells (hMSCs) with uncoated and coated titanium alloy implants with poorly crystalline apatite are studied. First the configuration and chemical composition of the apatite coatings and their deposition progress in different experimental conditions are investigated and discussed. Then, hMSCs are cultured on different substrates and cell attachment and proliferation are monitored and evaluated for different time intervals. Although the uncoated and coated substrates indicate good cell attachment, the differences in proliferation and morphology of the cells spread over the coated samples are significant. It is concluded that the coated samples improve the capability for accepting the cells in three-dimensional and slender shapes. The migration of hMSCs on both substrates are discussed. As such cell migration is directly associated to the osteoconduction, the findings confirm the hypothesis of enhancement in bone formation on the surface of biomimetically poorly crystalline apatite coated titanium implants. This in vitro study demonstrates that the coated samples are nontoxic and biocompatible enough for ongoing osteogenic studies in bone or dental defects in animal models in vivo.

Diamond as a scaffold for bone growth

Diamond is an attractive material for biomedical implants. In this work, we investigate its capacity as a bone scaffold. It is well established that the bioactivity of a material can be evaluated by examining its capacity to form apatite-like calcium phosphate phases on its surface when exposed to simulated body fluid. Accordingly, polycrystalline diamond (PCD) and ultrananocrystalline diamond (UNCD) deposited by microwave plasma chemical vapour deposition were exposed to simulated body fluid and assessed for apatite growth when compared to the bulk silicon. Scanning electron microscopy and X-ray photoelectron spectroscopy showed that both UNCD and PCD are capable of acting as a bone scaffold. The composition of deposited apatite suggests that UNCD and PCD are suitable for in vivo implantation with UNCD possible favoured in applications where rapid osseointegration is essential.

Improvement of Mechanical Properties of 3d Printed Hydroxyapatite Scaffolds by Polymeric Infiltration

Tailor made bioceramic scaffolds in combination with the corresponding surface chemistry and biology is of great importance for a successful implantation and rapid osseo-integration. The present study investigates the fabrication of Hydroxyapatite (HA) scaffolds with defined macro porosity by means of powder based 3D-printing. In order to mime natural bone with its elastic collagen structure, the 3D-printed ceramic structures were post-treated by polymeric infiltration. Compressive Strength analysis (CS) confirmed the positive impact of an elastomeric phase on mechanical properties. 3D-printed HA scaffolds in combination with polymer result in biodegradable scaffolds with promising mechanical properties for potential use in regenerative medicine.

Effect of magnesium and calcium phosphate coatings on osteoblastic responses to the titanium surface

PURPOSEThe aim of this study was to evaluate the surface properties and in vitro bioactivity to osteoblasts of magnesium and magnesium-hydroxyapatite coated titanium.MATERIALS AND METHODSThemagnesium (Mg) and magnesium-hydroxyapatite (Mg-HA) coatings on titanium (Ti) substrates were prepared by radio frequency (RF) and direct current (DC) magnetron sputtering.The samples were divided into non-coated smooth Ti (Ti-S group), Mg coatinggroup (Ti-Mg group), and Mg-HA coating group (Ti-MgHA group).The surface properties were evaluated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The surface roughness was evaluated by atomic force microscopy (AFM). Cell adhesion, cell proliferation and alkaline phosphatase (ALP) activity were evaluated using MC3T3-E1 cells. Reverse transcription polymerase chain reaction (RT-PCR) analysis was performed.RESULTSCross-sectional SEM images showed that Mg and Mg-HA depositionson titanium substrates were performed successfully. The surface roughness appeared to be similaramong the three groups. Ti-MgHA and Ti-Mg group had improved cellular responses with regard to the proliferation, alkaline phosphatase (ALP) activity, and bone-associated markers, such as bone sialoprotein (BSP) and osteocalcin (OCN) mRNA compared to those of Ti-S group. However, the differences between Ti-Mg group and Ti-MgHA group were not significant, in spite of the tendency of higher proliferation, ALP activity and BSP expression in Ti-MgHA group.CONCLUSIONMg and Mg-HAcoatings could stimulate the differentiation into osteoblastic MC3T3-E1 cells, potentially contributing to rapid osseointegration.

Effects of a Calcium Phosphate–Coated and Anodized Titanium Surface on Early Bone Response

The aim of this study was to evaluate the effectiveness of a calcium phosphate (CaPO4)-coated and anodized titanium surface in vitro and in vivo. A turned surface was employed as a negative control. A sandblasted/acid-etched surface and an anodized surface were used as positive controls, and a CaPO4-coated and anodized (CPA) surface was investigated as the experimental group. Surface characteristics were analyzed with field emission scanning electron microscopy, energy dispersive spectroscopy, and confocal laser scanning microscopy. In vitro osteoblastic differentiation was evaluated by alkaline phosphatase assay. In vivo bone response was analyzed using bone-to-implant contact (BIC) ratios and bone area (BA) of 2- and 4-week specimens obtained from six rabbits. The means and standard deviations for average height deviation (S(a)) and developed surface area ratio (S(dr)) were 0.32 ± 0.03 μm and 3.6% ± 1.5% for the turned group, 1.36 ± 0.11 μm and 56.7% ± 16.1% for the sandblasted/acid-etched group, 0.68 ± 0.02 μm and 50.9% ± 2.9% for the anodized group, and 0.67 ± 0.11 μm and 50.0% ± 16.9% for the CPA group. There were no significant differences in alkaline phosphatase activity among the groups at 7 and 14 days. In the in vivo experiment, the CPA group exhibited a significantly higher BIC ratio than the turned group, and the anodized and CPA groups showed significantly higher BA values than the others after 2 weeks. At 4 weeks, there was no significance in either BIC ratios or BA values among the groups. A CaPO(4) coating on an anodized surface may induce rapid osseointegration at the bone-implant interface and more bone formation near the implant surface.

Osseointegration of two different phosphate ion‐containing titanium oxide surfaces in rabbit cancellous bone

This study assessed the osseointegration of grit-blasted titanium (Ti) implants with a hydrophilic phosphate ion-incorporated oxide surface in rabbit cancellous bone, and compared its bone healing with commercially available phosphate-incorporated clinical implants obtained by micro-arc oxidation (TiUnite, TU implant). The hydrophilic phosphate-incorporated Ti surface (P implant) was produced by hydrothermal treatment on grit-blasted moderately rough-surfaced clinical implant. The TU surface was used as a control. The surface characteristics were evaluated by field emission-scanning electron microscopy, X-ray photoelectron spectroscopy, optical profilometry, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Thirty-two threaded implants with lengths of 10 and 3.3 mm diameter (16 P implants and 16 TU implants) were placed in the femoral condyles of 16 New Zealand White rabbits. Histomorphometric analysis, removal torque tests, and surface analysis of the torque-tested implants were performed 4 weeks after implantation. The P and TU implants displayed micro-rough surface features with similar Ra values at the micron-scale. ICP-AES analysis revealed that both the P and TU implants released phosphate ions into the solution. The torque-tested P and TU implants exhibited a considerable quantity of bone attached to the surface. The P implants exhibited significantly higher bone-implant contact percentages, both in terms of the all threads region and the total lateral length of implants compared with the TU implants (P < 0.01), but no statistical difference was found for the removal torque values. These results suggest that the phosphate-incorporated Ti oxide surface obtained by hydrothermal treatment achieves rapid osseointegration in cancellous bone by increasing the degree of bone-implant contact.

Effects of saliva or serum coating on adherence of Streptococcus oralis strains to titanium

The use of dental implants to treat tooth loss has increased rapidly over recent years. 'Smooth' implants showing high long-term success rates have successively been replaced by implants with rougher surfaces, designed to stimulate rapid osseointegration and promote tissue healing. If exposed in the oral cavity, rougher surfaces may promote bacterial adhesion leading to formation of microbial biofilms which can induce peri-implant inflammation. Streptococcus oralis is an early colonizer of oral surfaces and has been recovered from titanium surfaces in vivo. The purpose of this study was to examine the adherence of clinical strains of S. oralis to titanium with smooth or moderately rough surface topography and to determine the effect of a saliva- or serum-derived coating on this process. Adherence was studied using a flow-cell system with confocal laser scanning microscopy, while putative adhesins were analysed using proteomics of bacterial cell wall proteins. This showed that adherence to moderately rough surfaces was greater than to smooth surfaces. Serum did not promote binding of any of the studied S. oralis strains to titanium, whereas a saliva coating increased adherence in two of three strains tested. The higher level of adherence to the moderately rough surfaces was maintained even in the presence of a saliva coating. The S. oralis strains that bound to saliva expressed an LPXTG-linked protein which was not present in the non-adherent strain. Thus strains of S. oralis differ in their capacity to bind to saliva-coated titanium and we propose that this is due to differential expression of a novel adhesin.

Die Ausbildung von Knochengewebe an der Oberfläche von hydroxylapatitbeschichteten Prothesenschäften: eine radiologische Analyse

To facilitate implant osseointegration in the early postoperative period, coating of the implant surfaces with osseoconductive materials, e.g. hydroxyapatite (HA), is being increasingly recommended. It apparently reduces the rate of radiolucent lines and even improves the osseointegration of implants less well suited for cementless anchorage. We analysed HA-coated stems to find out whether newly formed bone adherent to the implant surface such as seen on explanted stems is also seen on radiographs and whether it follows a specific morphological pattern. We also wanted to know whether newly formed peri-implant bone extends over the entire length of the HA-coating, at which point in time it is seen radiographically and whether it expands within the first few years post implantation by radiological evidence. Radiographs of 40 unselected patients after primary total hip arthroplasty (THR), 14 males and 26 females, aged 44.4 to 86.7 years at the time of THR, with a mean age of 67.3 years were available for analysis. Monitor-guided a.-p. and axial views of the stems were obtained in the early postoperative period up to 6 weeks post THR, at a mean follow-up time of 1.3 (1.0 to 1.8) years and 3.0 (1.9 to 3.7) years. Tapered straight stems with a rectangular cross-section made of a wrought Ti6AI7Nb alloy with an HA coating in the proximal third were used. A.-p. views: At one year there were no signs suggesting an increased ongrowth of bone. At 3 years, on average, delicate bony appositions were seen on the implant surfaces in position 1 in three stems, in one of them also in position 7. These looked like a sclerotic zone lacking a sharp demarcation and were in direct contact with the implants without any bone-to-implant gaps. Axial views: At about one year two stems showed delicate bony appositions parallel to the implant surface in the proximal part in positions 8 and 9 as well as 13 and 14. Named "miniscleroses" by us, these structures were confined to the length of the HA coating. At three years these miniscleroses were clearly visible around 11 stems (more than 25 %). Those already seen at one year were much better defined at three years, but still confined to the HA-coated part of the stem. Some of them were poorly demarcated from the adjacent bone and medullary canal and some showed smooth demarcations. The density of the bony ongrowths was either homogeneous or increased from the medullary space or adjacent bone towards the implant surface. All of them were adherent to the implant surface. While not related to the peri-implant cortical bone, they were in contact with trabecular structures. After a mean follow-up time of one year radiolucent lines were seen around four stems in positions 1, 7 and 8. These were up to 1 mm in size around two stems and 2 mm or more in the other two. At 3 years all of the visible radiolucencies had disappeared except for one measuring 1 mm in position 8. The structures we found radiographically apparently reflect newly formed bone along the entire HA-coated implant surface. Most of them were located in positions 8, 9 and 13, 14. They provide visible evidence of osseointegration at osseoconductive surfaces. As they apparently did not have any contact with the peri-implant bone, they appear to be compatible with the bilateral osteogenesis according to Osborn. The effects of the rapid bony ongrowth on HA-coated surfaces and the striking absence of radiolucencies on the long-term outcome are still speculative. But the structures seen may be taken as a sign of improved implant stability by rapid osseointegration and of early sealing of the medullary canal. As a result, wear particles of the articulating surfaces are barred from spreading to the medullary cavity of the femur. This alone argues in favour of using coated implants throughout. However, more studies are needed to shed light on these issues.

How to Enhance Osseointegration – Roughness, Hydrophilicity or Bioactive Coating

The apposition of bone at early stages is critical for rapid loading and therefore there is much effort in improving the implant surfaces for a rapid osseointegration. The aim of this study is to investigate the effect of roughness, hydrophilicity and coating on osseointegration. Machined (smooth), sand-blasted (rough), hydrophilic and coated implants were testedin vivofor 2, 4 and 6 weeks. The hydrophilic surfaces were obtained by atmospheric oxygen plasma treatment of machined and sand-blasted implants. The coating is obtained by a spin-spray-process using sol-gel-technique. SEM and TEM investigations revealed that the coating consists of a nanoporous silica matrix with embedded synthetic, nanocrystalline hydroxyapatite. Histological polished sections were manufactured and the bone-to-implant-contact was calculated. The difference between smooth and rough implants was marginal and not significant. There were no statistical differences between hydrophilic and control implants, whereas the BIC of the hydrophilic surfaces was lower by trend. All coated implants offered an increased bone to implant-contact. However, the BIC was decreasing at 6 weeks due to the missing of mechanical stress and a faster bone metabolism in rabbits. The coating offers a new opportunity to enhance the osseointegration and therefore an earlier implant loading.

Adhesion and osteogenic differentiation of human mesenchymal stem cells on titanium nanopores

Titanium implants are widely used in orthopaedic and dental surgery. Surface properties play a major role in cell and tissue interactions. The adhesion and differentiation of mesenchymal stem cells were studied as a function of nanostructures. Titanium surfaces with nanopores 30, 150 and 300 nm in diameter were prepared by physical vapour deposition. PCR arrays indicated that the expression of integrins was modulated by the nanopore size. Human Mesenchymal Stem Cells (hMSCs) exhibited more branched cell morphology on Ti30 than on other surfaces. Ti30 and Ti150 induced osteoblastic differentiation while Ti300 had a limited effect. Overall, nanopores of 30 nm may promote early osteoblastic differentiation and, consequently, rapid osseointegration of titanium implants.

Selectively Promoting or Preventing Osteoblast Growth on Titanium Functionalized with Polyelectrolyte Multilayers

AbstractTitanium plays an important role in medical applications, such as hip joint implants or fixation plates. These implants must perform differently depending on their clinical application. In particular, the osseointegrative properties required of the implant vary with clinical application. The present work is aimed at the functionalization of titanium surface using polyelectrolyte multilayers consisting of natural biopolymers and testing their cell adhesive properties with respect to the osseointegration capacity.Multilayered coatings were created from chitosan (Chi), hyaluronic acid (HA), and gelatine (Gel) through layer‐by‐layer deposition. Cell adhesion, proliferation, and viability were tested in vitro with the human osteoblast cell line CAL‐72 at timescales up to 7 d. Two multilayer coatings consisting of alternated chitosan/gelatin or chitosan/hyaluronic acid layers with the outmost layer of gelatin (Chi/Gel) or hyaluronic acid (Chi/HA), respectively, were tested. The experimental results showed that surfaces functionalized with Chi/Gel and Chi/HA multilayers demonstrated a good initial adhesion of osteoblasts. After 4 d culturing, osteoblast cells were almost completely detached from the substrates functionalized with Chi/HA multilayers. In contrast to Chi/HA, the proliferation of osteoblasts on substrates with Chi/Gel multilayer coatings was statistically significantly higher compared to the control titanium.We have shown that the growth of osteoblasts can be enhanced or completely prevented on a titanium surface functionalized with polyelectrolyte multilayers consisting of natural biopolymers, as desired. Both multilayer coatings, Chi/Gel and Chi/HA, have potential for applications in the field of titanium implants, where rapid osseointegration is essential, and/or where no ingrowth of the implant is desired, respectively.

Bone augmentation after soft‐tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration

The success of bone augmentation, for example of the alveolar ridge, might be endangered by dehiscence of the soft tissue that covers the augmented bone. Soft-tissue coverage can be achieved without tension through pre-augmentation tissue expansion with hydrogel expanders. We used a periosteal chamber to study the influence of tissue expansion on microcirculation and osseointegration in an in vivo animal model. Sixteen isogeneic Lewis rats were randomised into two groups. Additional eight animals served as donors of isogeneic bone grafts (Group 3, n=8). The bone grafts were harvested and implanted into Group 1 animals (n=8) (without tissue expansion) and Group 2 animals (after tissue expansion). In Group 2 (n=8), hydrogel expanders were inserted subperiosteally at the site to be augmented for 21 days. We used intravital microscopy to monitor microcirculation in vivo for 19 days after implantation. Specimens from both groups were evaluated histologically. During the entire study period, functional microvessel density in the region above the augmentation material was significantly higher after previous tissue expansion (P>0.05). Both groups showed physiological microcirculation around the augmentation material. Histology revealed bone osseointegration of the bone graft in the group with tissue expansion and the presence of connective and granulation tissue in the group without tissue expansion. Pre-augmentation soft-tissue expansion with hydrogel expanders leads to higher functional microvessel density in the tissue above the augmentation material and thus, to more rapid osseointegration. The use of hydrogel expanders appears to increase the probability of success, especially of pre-implant bone augmentation.

The Effect of Nanotubular Titanium Surfaces on Osteoblast Differentiation

The biological response of fetal rat calvarial cells on a TiO2 nanotubular surface (Ti-NT) was evaluated by cell viability assay, alkaline phosphatase (ALP) activity and reverse transcription polymerase chain reaction (RT-PCR) analysis. The cell viability assay showed no significant difference between the Ti-NT and smooth titanium surfaces (Ti-S). Ti-NT had better cellular responses with regard to the ALP activity and bone-associated markers, such as bone sialoprotein and osteocalcin mRNA than Ti-S. These results suggest that Ti-NT stimulate the differentiation into osteoblasts of fetal rat calvarial cells, potentially contributing to rapid osseointegration.

Early Results of a New Highly Porous Modular Acetabular Cup in Revision Arthroplasty

The 'Tritanium' (Stryker, New Jersey, USA) highly porous acetabular cup is a new implant used in revision hip arthroplasty. To determine the early results of this device. A prospective study of 43 acetabular component revisions performed using the implant between March 2007 and February 2008 was undertaken. All procedures were performed at a single centre with standard approach and follow up. The mean age of patients at surgery was 66 years. Mean follow up was 18.2 months. AAOS classification revealed 17% Type 1, 49% Type 2, 24% Type 3 and 5% Type 4 defects at surgery. 5% had no bone defect. Bone graft was used to in 73% of patients. Mean Harris Hip Score improved from 68 pre-operatively to 86 at the last follow-up. Cup integration was seen in 95% of patients by 6 weeks. One patient with pelvic discontinuity had symptomatic aseptic loosening which was revised. The 'Tritanium'acetabular cup has been successful in achieving rapid osseointegration with few complications. The management of pelvic discontinuity continues to be a challenge.