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PubMed2004

[A new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique: a case report].

OBJECTIVE: To design and manufacture a new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique and explore a method to solve the necroses of allocartilage in hemi joint allotransplantation. METHODS: Design the new custom-made artificial articular cartilage of femoral condyle. The allograft and the patient distal femurs were scanned with Picker 6000 spiral computed tomography (CT) with 1.0 slice thickness and pitch of 1.5, reconstructed the distal femurs in Voxel Q image workstation with volume rendering technique. Then downloaded the transaxial 2D image data to personal computer at 0.1 mm interval and converted it into 2D digitized contour data by using image processing software developed by our team. The 3D wire frame and solid images of femoral condyle could be reconstructed when the 2D digitized contour data were input into image processing software Surfacer 9.0 (Imageware Company, USA). Subsequently based on the clinical experience and the need of design, the 3D contour image of articular cartilage was extracted from the surrounding. Based on the extracted 3D contour image, the computer-aided design (CAD) of the custom-made artificial articular cartilage was accomplished in Surfacer software, converted the CAD model into RP data format. Standard triangularization language, imported into the LPS600 rapid prototyping machine (Hengtong Company, Xi'an Jiaotong University, China), and the resin prototype was achieved. Then the resin model was used as a positive mould to build up a silica gel negative mould, the negative mould was sent to the factory to manufacture Ti-6Al-4V alloy articular cartilage through ordinary mould-melted founding process. Finally, the whole metal cartilage was completed after melting two special cages on it. A patient was selected to clinical applying. RESULTS: A new custom-made artificial articular cartilage of femoral condyle was made. It was press-fit well to the subchondral bone of the allograft bone. The patient's one and half year follow-up result was excellent. CONCLUSIONS: We design and manufacture a new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique. The result shows that the manufacturing process has the advantage of rapidness and precision that are very important for individualized artificial implant manufacturing. The artificial articular cartilage is press-fit well and could be a good idea to solve the necroses of allocartilage in hemijoint allotransplantation.

Adolescent↗

PubMed2004

Microrough implant surface topographies increase osteogenesis by reducing osteoclast formation and activity.

Titanium implant surfaces with rough microtopographies exhibit increased pullout strength in vivo suggesting increased bone-to-implant contact. This is supported by in vitro studies showing that as surface microroughness increases, osteoblast proliferation decreases whereas differentiation increases. Differentiation is further enhanced on microrough surfaces by factors stimulating osteogenesis including 1alpha,25(OH)2D3. Levels of PGE2 and TGF-beta1 are increased in cultures grown on rough microtopographies; this surface effect is enhanced synergistically by 1alpha,25(OH)2D3-treatment. PGE2 and TGF-beta1 regulate osteoclasts as well as osteoblasts, suggesting that surface microtopography may modulate release of other factors from osteoblasts that regulate osteoclasts. To test this hypothesis, we examined the effects of substrate microarchitecture on production of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL), which have been identified as a key regulatory system of bone remodeling. We also examined the production of 1alpha,25(OH)2D3, which regulates osteoblast differentiation and osteoclastogenesis. MG63 osteoblast-like cells were grown on either tissue culture plastic or titanium disks of different surface microtopographies: PT (Ra < 0.2 microm), SLA (Ra = 4 microm), and TPS (Ra = 5 microm). At confluence, cultures were treated for 24 h with 0, 10(-8) M or 10(-7) M 1alpha,25(OH)2D3. RANKL and OPG were determined at the transcriptional level by RT-PCR and real time PCR and soluble RANKL, OPG and 1alpha,25(OH)2D3 in the conditioned media were measured using immunoassay kits. Cell number was reduced on SLA and TPS surfaces and 1alpha,25(OH)2D3 caused further decreases. OPG mRNA levels increased on rougher surfaces and 1alpha,25(OH)2D3 treatment caused a further synergistic increase. While the cells expressed RANKL mRNA, levels were low and independent of surface microtopography. OPG protein was greater when cells were grown on SLA and TPS. 1alpha,25(OH)2D3 increased OPG by 50% on the smooth Ti surface but on SLA, 10(-8) M 1alpha,25(OH)2D3 caused a 100% increase and 10(-7) M 1alpha,25(OH)2D3 increased OPG by 200%. On TPS 10(-7) M 1alpha,25(OH)2D3 increased OPG 350%. Soluble RANKL was not detected in the conditioned media of any of the cultures. 1alpha,25(OH)2D3 was produced endogenously and levels were positively correlated with surface roughness. Thus, on surfaces with rough microtopographies, osteoblasts secrete factors that enhance osteoblast differentiation while decreasing osteoclast formation and activity.

Animals↗

PubMed1995

Effect of nickel addition on microstructure and properties of Ti-Co-Ni alloys.

The focus of this study was placed on the effect of nickel addition (5 wt%) on the microstructure, castability, biocorrosion resistance and some other properties of a series of cast high-cobalt (up to 25 wt%) Ti-Co-Ni alloys. Results indicated that melting temperatures of the present alloys were much lower than the melting temperature of pure titanium. Addition of 5 wt% Ni to replace an equivalent amount of Co slightly lowered the eutectoid and melting temperatures. Castability of the alloys was enhanced by the high alloy content and higher mould temperature. Substitution of 5 wt% Ni for Co increased the castability values. The phase transformation of beta-Ti to alpha-Ti was enhanced by nickel addition and higher mould temperature. Microhardness of the alloys increased with cobalt content and decreased with mould temperature. The addition of nickel lowered the hardness of the alloys. Breakdown potentials of the alloys were all higher than 900 mV and the critical anodic current densities were all lower than 8 microA cm-2.

Alloys↗

PubMed2007

Electrochemical processes of nucleation and growth of hydroxyapatite on titanium supported by real-time electrochemical atomic force microscopy.

Recently, interest in electrochemical formation of hydroxyapatite has evolved. In this work, highly crystalline hydroxyapatite is electrodeposited on pure titanium and Ti-6Al-4V alloy. In situ and ex situ imaging, coupled with potentiostatic and potentiodynamic measurements, is conducted by means of electrochemical atomic force microscopy. This allows for a study of the nucleation and growth of hydroxyapatite as well as of its near-atomic structure. Electrodeposition of hydroxyapatite is shown to result from precipitation in solution, following two stages: (1) instantaneous nucleation, two-dimensional growth; (2) progressive nucleation, three-dimensional growth. Although some nucleation occurs already at -842 mV, potentials that are more negative than -1.26 V versus SCE are required for enhanced growth. Mass transport is found to have only secondary effect on the deposition process. The conclusions of this work have implications in optimization of coatings on implants as well as in enhancement of the understanding of bone mineralization in vivo.

Biomimetic Materials↗

PubMed2003

Influence of sterilization on the mineralization of titanium implants induced by incubation in various biological model fluids.

The aim of this work was to investigate the effect of the sterilization processes on the mineralization of titanium implants induced by incubation in various biological model fluids. Titanium samples were submitted to the following sterilization processes used for implant materials: steam autoclaving, glow discharge Ar plasma treatment and gamma-irradiation. The modification of the treated surfaces was evaluated by contact angle determinations, X-ray photoelectron spectroscopy (XPS), laser profilometry and X-ray diffraction. The most significant modifications were detected on the wettability: while the samples treated with Ar plasma became highly hydrophilic (water contact angle approximately 0 degrees), gamma-irradiation and steam sterilization induced an increase in the hydrophobicity. After being sterilized, the samples were incubated for one week in three biological model fluids: Hanks' Balanced Salt Solution, Kokubo's simulated body fluid (SBF) and a fluid, designated by SBF0, with the same composition of SBF but without buffer TRIS. The level of mineralization of the incubated Ti samples, assessed by dynamic contact angle analysis, scanning electron microscopy, electron dispersive spectroscopy and XPS, indicated that the early stages of mineralization are essentially independent of the sterilization method. In contrast, the incubating fluid plays a determinant role, SBFO being the most efficient medium for biomineralization of titanium.

Biocompatible Materials↗

PubMed1999

Effects of cyclic bending and physiological solution on plasma-sprayed hydroxylapatite coatings of varying crystallinity.

This study investigated the effects of cyclic bending stress levels and testing in simulated physiological solutions or air on the integrity of plasma-sprayed hydroxylapatite (HA) coatings of two different crystallinities. Hydroxylapatite-coated commercially pure (CP) Ti rods were evaluated by immersion testing in Hank's Balanced Salt Solution (HBSS) and by rotating bending in air and HBSS. Static immersion testing of nonstressed specimens resulted in significant microcracking of coating surfaces after 42 days. Specimens cyclically tested at bending stresses above the yield strength of Ti experienced low cycle fatigue failure of the Ti substrates prior to spallation of the HA coatings. Coatings tested at 1 x 10(6) cycles with interface bending stresses of 180 MPa displayed increased surface microcracking, but no bulk coating spallation. Coatings cycled in HBSS displayed greater amounts of microcracking and surface alteration than samples cycled in air. There was no apparent relation between HA crystallinity and mechanical integrity under cyclic bending stresses.

Air↗

PubMed1992

Bone tissue growth enhancement by calcium phosphate coatings on porous titanium alloys: the effect of shielding metal dissolution product.

The possible mechanism of minimization of prosthesis-derived bone growth inhibitors by shielding of the metal and the reduction, if not elimination, of the associated metal dissolution was investigated. Titanium, aluminium and vanadium release rates were determined in vitro for Ti alloy specimens both with and without a calcium phosphate coating. Ti orderly oriented wire mesh (OOWM) porous coatings on Ti-6Al-4V substrates were used as the metal specimens. Half of the specimens were coated with a 75 microns calcium phosphate ceramic (CPC coating). Seven reference (OOWM) and seven coated (OOWM-CPC) specimens were immersed and placed along with seven control solutions for various periods in an incubator maintained at 37 degrees C and 5% CO2 - air atmosphere. Whereas the reference solutions showed a Ti release increasing as a function of time, the solutions that had the CPC-coated specimens contained no measurable amounts of titanium. The Al in solution around the CPC-coated specimens was significantly greater than the concentration around non-coated specimens. The Al, however, did not increase significantly with time, at least up to 4 wk immersion. The ceramic coating had a small beneficial effect on V concentration. In the absence of a significant adverse effect of Ti on local bone tissue formation, we focus on the Al data of our study. The possible adverse effect of this element is well documented. The calcium phosphate coating produced a significant increase of biological fixation, yet at the same time a greater Al release into solution, calling into question the significance of CPC coating in shielding adverse metal passive dissolution to explain enhanced bone growth [corrected].

Alloys↗

PubMed2005

A biomechanical comparison of the Mitek RapidLoc, Mitek Meniscal repair system, clearfix screws and vertical PDS and Ti-Cron sutures.

The aim of this in vitro study was to measure and compare the biomechanical properties and mode of failure of the five different methods of meniscal repair. Reproducible tears were created in 50 bovine medial menisci and repaired in a standardized fashion with one of the following devices: the RapidLoc meniscal repair device (Mitek Products, Westwood, MA), an 8 mm Mitek meniscal repair system (Mitek Products, Westwood, MA), Clearfix screw (Innovasive Devices, Marlborough, MA), a single vertical mattress suture of 2-0 Ti-Cron (Ethicon, Massachusetts) and a vertical mattress suture of No. 1 PDS II (Johnson and Johnson Int.). The repairs were tested by single cycle load to failure in a materials testing machine. The mean loads to failure for each of the repair groups were as follows: Mitek RapidLoc 44.9 N, Mitek meniscal repair system 20.3 N, Clearfix screw 37.4 N, vertical Ti-Cron 66.1 N and vertical PDS suture 103.0 N. The mean load to failure was significantly greater with PDS vertical sutures than with other techniques (P<0.05). The Mitek RapidLoc had the least extension at failure (14.8 mm) (P<0.05). This study confirms meniscal repair with vertical PDS sutures confers the highest biomechanical stability and that the new Mitek RapidLoc device offers improved load to failure than the previous generations.

Absorbable Implants↗

PubMed2002

TGF-beta1 secretion of ROS-17/2.8 cultures on NiTi implant material.

The biocompatibility of an orthopedic implant depends on the effect of the implant on bone-forming cells, osteoblasts. Changes in osteoblastic proliferation, maturation and differentiation are important events in ossification that enable monitoring the effect of the implant. Transforming growth factor-beta (TGF-beta) is known to suppress osteoblast proliferation and, on the other hand, to induce the maturation and differentiation of osteoblasts. Moreover, osteoblasts produce TGF-beta, which is embedded in the bone matrix and activated by bone-resorbing osteoclasts. TGF-beta inhibits osteoclastic activity. Here, we show for the first time the effect of nickel titanium shape memory metal (NiTi) on osteoblastic cytokine expression. In this study, we measured the levels of TGF-beta with enzyme-linked immunosorbent assay (ELISA) from a ROS-17/2.8 osteosarcoma cell line cultured on different metal alloy discs. ELISA results were proportioned to total DNA content of the samples. We compared NiTi, to stainless steel (Stst), pure titanium (Ti) and pure nickel (Ni). The TGF-beta1/DNA value in the NiTi group (0.0007 +/- 0.0003) was comparable with those seen in the Stst (0.0008 +/- 0.0001) and Ti (0.0007 +/- 0.0001) groups. The concentration in the Ni group was lower (0.0006 +/- 0.0003), though not statistically significantly so. In addition, the effect of surface roughness on TGF-beta1 production was studied. We compared three different grades of roughness in three differently hot-rolled alloys: NiTi. hot-rolled at 950 degrees C. Ti alloy hot-rolled at 850 degrees C (TiI) and the same Ti alloy hot-rolled at 1,050 degrees C (TiII). We found that increasing roughness of the NiTi surface increased the TGF-beta1 concentration. On the other hand, all roughness groups of TiII showed low levels of TGF-beta1. while a rough TiI surface induced similar TGF-beta1, expression as rough NiTi. Further, these same measurements made with interleukine 6 (IL-6) were found to be under the detection limit in these cultures. We conclude that a rough NiTi surface promotes TGF-beta1 expression in ROS-17/2.8 cells.

Animals↗

PubMed1984

Metal/cement interface strength in cemented stem fixation.

To characterize the strength of the interface between stem-type metal implants and bone cements, a fracture mechanics parameter was used. This parameter, the critical strain energy release rate (Gc), was determined from "push-out" tests of cylindrical specimens. The specimens, formed using molds of bone, were maintained and tested at body temperature. The strength of interfaces formed with cancellous bone surrounding the cement mantle was significantly less than the strength of those formed in apposition to cortical bone. A marked degradation of strength was found with saline immersion for SS316LVM/cement interfaces formed with Zimmer regular, Simplex-P, and Zimmer LVC cements. After 60 days of immersion the interface Gc was only 10-20% of the value for bulk cement. Interfaces formed with thin-film polymethylmethacrylate-precoated metals (SS316LVM, Co-Cr-Mo, and Ti-6A1-4V) yielded "dry" Gc values one order of magnitude greater than those measured with interfaces formed with uncoated metals. Moreover, the strength of precoated SS316LVM/cement interfaces formed with all three brands of cement did not change after saline immersion for 60 days.

Alloys↗

PubMed1995

Complex asparagine-linked oligosaccharides in Mgat1-null embryos.

To investigate the developmental role of complex N-linked oligosaccharides, we previously inactivated the mouse Mgat1 gene which encodes UDP-N-acetylglucosamine: alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I (GlcNAc-TI). Mgat1-null embryos developed morphogenic abnormalities by embryonic day (E) 9.5 and failed to survive beyond E10.5. Prior to E8.5, mutant and wild-type embryos were phenotypically indistinguishable, raising the unexpected possibility that earlier embryonic development may not require complex N-glycans. We have now used in situ RNA hybridization to assess the temporal and spatial pattern of Mgat1 expression in normal embryos, and lectin histochemistry to determine whether Mgat1-null embryos lack complex N-glycans at pre-E9.5 developmental stages. In situ RNA analysis indicated that Mgat1 transcripts normally increase dramatically between E7.0 and E9.5, 1-2 days prior to the death of mutant embryos. However, apparently normal levels of complex N-glycans were observed in E3.5 pre-implantation Mgat1-null embryos prior to declining to undetectable levels by E7.5. Complex N-glycans were not observed in E7.5-E9.5 Mgat1-null embryos with the notable exception of vesicular structures within cells of the visceral extra-embryonic endoderm, perhaps reflecting the ability of these cells to take up and transport maternally derived glycoproteins. Mgat1-null embryos appear to complete pre-implantation development in the presence of maternally derived complex N-glycans, and may die at later stages, post E7.5, when a requirement for embryonically derived complex N-glycans arises.

Animals↗

PubMed2003

Mechanical properties and Young's modulus of plasma-sprayed hydroxyapatite coating on Ti substrate in simulated body fluid.

This study evaluated the Young's modulus, residual stress and strain, bonding strength, and microstructure of the plasma-sprayed hydroxyapatite coating (HAC) on Ti6Al4V substrate with and without immersion in Hank's balanced salt solution (HBSS). The purpose was to explore the possible correlation of HAC durability and mechanical properties of the coating. The results show that the residual stress and strain, Young's modulus, and bonding strength of the HAC after immersion in HBSS are substantially decreased. The decayed Young's modulus and mechanical properties of HACs are accounted for by the degraded interlamellar or cohesive bonding in the coating due to the increased porosity after immersion that weakens the bonding strength of coating and substrate system. The biologic implications of the research are discussed in detail. This study contributes to the arguments that the method to alleviate the dissolution of HAC will increase the bonding strength of the coating system after immersion, which together with the controlled residual stress and strain in the coating might promote the long-term stability of the HA-coated implant.

Adhesiveness↗

PubMed1993

In-vitro evaluation of the cytocompatibility of wear particles generated by UHMWPE/zirconia friction.

Cytotoxicity of wear products generated by UHMWPE/yttria partially stabilized zirconia (YPSZ) friction and UHMWPE/surface-nitrided Ti-6Al-4V friction in pseudo-extracellular fluid (PECF) at 37 degrees C was evaluated. Though the amount of abraded UHMWPE against YPSZ was almost the same as that against nitrided Ti-6Al-4V, the wear products generated by UHMWPE/YPZ friction significantly inhibited cell growth while those by UHMWPE/nitrided Ti-6Al-4V friction showed no growth inhibition. Dissolved Zr and Y ions were at least 70 times less than the amount causing growth inhibition. The cytotoxicity was caused mainly by the particles less than 0.22 mum in size. Amorphous zirconium-containing particles (5-20 nm) found in the PECF, formed presumably by stress corrosion, would be a responsible factor for the cytotoxicity.

Biocompatible Materials↗

PubMed2004

Increased osteoblast adhesion on nanophase metals: Ti, Ti6Al4V, and CoCrMo.

Previous studies have demonstrated increased functions of osteoblasts (bone-forming cells) on nanophase compared to conventional ceramics (specifically, alumina, titania, and hydroxyapatite), polymers (such as poly lactic-glycolic acid and polyurethane), carbon nanofibers/nanotubes, and composites thereof. Nanophase materials are unique materials that simulate dimensions of constituent components of bone since they possess particle or grain sizes less than 100 nm. However, to date, interactions of osteoblasts on nanophase compared to conventional metals remain to be elucidated. For this reason, the objective of the present in vitro study was to synthesize, characterize, and evaluate osteoblast adhesion on nanophase metals (specifically, Ti, Ti6Al4V, and CoCrMo alloys). Such metals in conventional form are widely used in orthopedic applications. Results of this study provided the first evidence of increased osteoblast adhesion on nanophase compared to conventional metals. Interestingly, osteoblast adhesion occurred preferentially at surface particle boundaries for both nanophase and conventional metals. Since more particle boundaries are present on the surface of nanophase compared to conventional metals, this may be an explanation for the measured increased osteoblast adhesion. Lastly, material characterization studies revealed that nanometal surfaces possessed similar chemistry and only altered in degree of nanometer surface roughness when compared to their respective conventional counterparts. Because osteoblast adhesion is a necessary prerequisite for subsequent functions (such as deposition of calcium-containing mineral), the present study suggests that nanophase metals should be further considered for orthopedic implant applications.

Alloys↗

PubMed1999

A randomized trial of hydroxyapatite coated prostheses in total hip arthroplasty.

In a prospective randomized trial, 62 consecutive primary cementless total hip arthroplasties in 55 patients were performed by one surgeon using either hydroxyapatite coated (35 hips) or nonhydroxyapatite coated femoral prostheses (27 hips). The dual tapered femoral stem had a Ti-6AI-4V plasma sprayed circumferential proximal porous coat applied to the proximal 1/3 of the stem. The middle 1/3 had a roughened blasted textured surface, and the distal 1/3 had a smooth surface. The hydroxyapatite coated femoral stems had an additional hydroxyapatite coating applied to the proximal porous coat with use of an air plasma process. The patients in the two groups were not significantly different regarding age (48.2 +/- 9.0 years hydroxyapatite group, 50.4 +/- 8.7 years control group), gender, Charnley class, or length of followup (4.4 +/- 0.7 years hydroxyapatite group, 4.9 +/- 1.0 years control group). Forty-nine patients (54 hips) were available for clinical followup, and 45 patients (50 hips) had radiographic followup. A minimum 3-year followup was recorded. To date, there have been no femoral prostheses failures. No femoral implant has migrated or subsided. Radiographically, the hydroxyapatite coated stems showed trends toward increased distal stem related cortical hypertrophy, increased cancellous condensation and less endosteal cavitation. Two nonhydroxyapatite coated stems had distal endosteal cavitation, whereas no hydroxyapatite coated stems did. There were two cases of acetabular osteolysis (revision in one) and two cases of acetabular cup migration (nonrevised), all occurring in the control group. The overall revision rate was 4%. There was no difference in Harris hip scores at 6 months (80.6 +/- 13.0 points hydroxyapatite group, 83.8 +/- 12.4 points control group) or at last followup (85.6 +/- 15.4 points hydroxyapatite group, 89.7 +/- 13.4 control group). The Harris hip pain scores also were not significantly different at 6 months or at last followup. Multiple linear regression analysis controlling for age, gender, and length of followup revealed no significant predictors of Harris hip or pain scores. The results of this study at an average of 4.6 years do not indicate a significant clinical advantage to the use of hydroxyapatite coated femoral prostheses in primary cementless total hip arthroplasty when judged by the criteria of Harris hip scores and femoral stem survivorship.

Acetabulum↗

PubMed2004

Optic nerve regeneration in polyglycolic acid-chitosan conduits coated with recombinant L1-Fc.

Autografts have been extensively studied to facilitate optic nerve (ON) regeneration in animal experiments, but the clinical application of this approach to aid autoregeneration has not yet been attempted. This study aims to explore the guided regeneration by an artificial polyglycolic acid-chitosan conduit coated with recombinant L1-Fc. Consistent with previous studies; in vitro assay showed that both chitosan, a natural biomaterial, and the neural cell adhesion molecule L1-Fc enhanced neurite outgrowth. Rat optic nerve transection was used as an in vivo model. The implanted PGA-chitosan conduit was progressively degraded and absorbed, accompanied by significant axonal regeneration as revealed by immunohistochemistry, anterograde and retrograde tracing. The polyglycolic acid-chitosan conduit coated with L1-Fc showed more effective to promote axonal regeneration and remyelination. Taken together, our observations demonstrated that the L1-Fc coated PGA-chitosan conduits provided a compatible and supportive canal to guild the injured nerve regeneration and remyelination.

Animals↗

PubMed2004

Vitronectin adsorption on surfaces visualized by tapping mode atomic force microscopy.

Vitronectin (Vn) is an abundant glycoprotein present in plasma and the extracellular matrix of most tissue and is an important medium required for bone cells to attach and spread on biomaterial surfaces. Hence, Vn adsorption is an initial and key step in implantation. In this study, adsorption of Vn molecules on mica and oxidized titanium substrates in Milli-Q water (pH 5.6) and in simulated body fluid (SBF, pH 7.4) has been investigated using tapping mode atomic force microscopy. Conformation of the adsorbed proteins was determined from the images. The effect of adsorption time was investigated on mica surfaces. The protein first attaches to the surface, then immediately spreads out with different lateral dimensions of adsorbed protein and becomes aggregated. After 15 min of adsorption, globular Vn molecules form clusters of aggregates in extended chains on the mica surface. Globular Vn molecules appear flatter (i.e., oblate ellipsoids) and coalesce on the ridges of the uneven oxidized titanium surface. From cross-sectional analyses of the Vn images, it was found that the contact areas of Vn molecules associated with Ti surfaces are larger than those with mica surfaces. This suggests that the different surface properties of substrates contribute to this different conformation of adsorbed Vn molecules. The larger contact areas of Vn associated with Ti substrates indicates higher affinity for the biomaterial oxidized titanium surface than for mica. In SBF, Vn interacted weakly with the mica surfaces and Vn molecules were easily desorbed during the imaging process. On oxidized titanium substrates, after 3 h of incubation time in Vn-SBF solution, images can be obtained showing adsorbed Vn aggregates on the oxidized titanium surface. In this case, the protein colloids are strongly adherent, with increased lateral dimensions compared with the adsorption on mica.

Adsorption↗

PubMed2003

Indirect reduction and bridge plating of supracondylar fractures of the femur.

Between October 1995 and December 1998, 16 patients with A-O type A3, C2 or C3 supracondylar femoral fractures were treated by open reduction and internal fixation using indirect reduction and bridge plating. Seven (44%) patients had open fractures. The patients were followed for a mean of 46 months (range 24-71). All fractures healed. The average time for fracture healing was 18.5 weeks (range 12-28). Four primary bone grafts and three secondary bone grafts were performed. By using the modified Schatzker rating scale, the result of 13 patients (81%) were rated as excellent or good. Complications included two implant failures that were due to full weight bearing before bone healing, and one superficial delayed wound healing. No deep infections were found in this series. The open fracture group needed longer time to heal and had a higher rate of receiving bone grafts. We conclude that indirect reduction and bridge plating with a 95 degrees dynamic condylar screw (DCS) or condylar blade plate can produce favourable results for complex distal femoral fractures. We suggest primary bone grafts or early secondary bone grafts for comminuted open fractures using an indirect reduction technique.

Adolescent↗