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At least 1,711 records · Page 95Linked to original sources
PubMed1995

Titanium as the material of choice for cementless femoral components in total hip arthroplasty.

Modern total hip arthroplasty has been performed using femoral stems manufactured from stainless steel, cobalt-chrome molybdenum alloy (CoCrMb), titanium aluminum vanadium alloy (TiAlV), and, on a limited basis, low-elastic modulus composites. Today, only CoCrMb and TiAlV are used in significant numbers. There is ample theoretical, experimental, and clinical evidence to support Ti-AlV as the material of choice for cementless femoral stems, based on superior mechanical compatibility and biocompatibility. The primary advantage of TiAlV over CoCrMb is a lower modulus of elasticity. This results in decreased stress shielding and subsequent favorable femoral remodeling. This effect is more significant with the smaller stem sizes used in primary surgery but persists even with larger stem sizes used in revision surgery. The second advantage of TiAlV is its biocompatibility. Titanium aluminum vanadium alloy is of relatively low toxicity in concentrations found clinically, and TiAlV is inert in the physiologic environment. With regard to fixation in cementless total hip arthroplasty, TiAlV has been shown to achieve excellent bone ingrowth into porous surfaces. In addition, there is evidence of superior bony ingrowth into TiAlV as compared with CoCrMb. Titanium aluminum vanadium alloy is presently the material of choice to be used in conjunction with hydroxyapatite coating. Prosthetic design, stem diameter, and porous-coating applications play significant roles in bony response regardless of metal composition.

Biocompatible Materials↗
PubMed1995

Titanium nitride ceramic film against polyethylene. A 48 million cycle wear test.

Wear is a major late complication of total joint arthroplasty, particularly for younger, active patients. Many patients could produce > 40 million motion cycles after joint replacement. Based on current experience and testing, typical joint prostheses are likely to wear out, and need revision in such patients. One problem is degradation of the metal (counterface) surface. A harder, more abrasion resistant, counterface surface is needed. This study evaluated the long-term wear of the titanium nitride ceramic film against ultra high molecular weight polyethylene. In this test, 4 47-mm femoral cups with a polished 8-micron-thick titanium nitride coating were run against 4-mm-thick metal-backed polyethylene bearings machined from GUR415 extruded rod in water at 37 degrees C at 5 Hz and a 2200-N fluctuating load. Wear of the counterface and bearing were extremely low. The average maximum reduction in thickness of the polyethylene was < 0.02 mm, and < 2 microns in the ceramic film. The average polyethylene wear rate was only approximately 2% of that found in a similar test using 32-mm cobalt chromium femoral heads. The titanium nitride-polyethylene couple has great potential as a lifetime bearing combination.

Alloys↗
PubMed1994

Ingrowth surfaces. Plasma spray coating to titanium alloy hip replacements.

Plasma spray coatings on titanium alloy total hip replacements (THRs) provide a viable alternative to sintered bead or diffusion-bonded fiber metal ingrowth surfaces. The plasma spray process enables the titanium alloy implant to retain 90% of its fatigue strength, as opposed to less than 50% for sintered or diffusion-bonded cementless devices. Laboratory and clinical evidence suggest that plasma spray cementless THRs perform as well, if not better, than other cementless implants. Clinical trials have demonstrated the superiority of a plasma spray cementless THR (Mallory-Head) over a sintered bead cementless THR (PCA) and the equivalent results to a cemented THR. Plasma spray coatings on titanium alloy hip replacements provide a safe, predictable coating for cementless fixation of THRs in the short to medium range of follow-up periods.

Adult↗
PubMed1993

[Titanium implant as an alternative possibility in fusion of the cervical vertebrae--initial clinical experiences].

We report on our experience with the use of titanium for disc replacement in the cervical spine. In 52 patients a total of 55 titanium grafts were implanted. Follow-up examinations were available in 48 patients with an observation time of 14 month on average. Results of clinical-neurological examinations were excellent or good in 37 patients (77%), moderate in 9 cases (19%), while two patients (4%) showed poor outcome. Radiological follow-up examinations showed a correct position in 47 of the 48 patients. Incorrect position as observed in 1 case made operative revision necessary. According to our results, titanium grafts seem to be a useful alternative method as compared to conventional techniques of fusion. Essential advantages are simple handling, biocompatibility of the material as well as the solid bond achieved by the special qualities of the graft with respect to surface and form. Availability of different graft sizes allows tailored fusion.

Adult↗
PubMed1993

The effects of hyperbaric oxygenation on bone-titanium implant interface strength with and without preceding irradiation.

This study investigated the influence of a single 15-Gy dose of irradiation on the capacity of titanium screws to integrate in irradiated bone tissue. The biomechanical force necessary to unscrew the titanium implants 8 weeks after placement was 54% lower for implants in irradiated bone tissue compared to implants in nonirradiated bone tissue. Postirradiation use of hyperbaric oxygen treatment at 2.8 ATA (2-hour daily treatments for 21 days) increased the biomechanical force necessary to unscrew the titanium implants by 44% in irradiated bone and by 22% in nonirradiated bone.

Animals↗
PubMed1993

Failure of a well-fixed bone-ingrown titanium hip prosthesis.

A cementless titanium femoral stem was revised 5 years after implantation because of acute pain and progressive osteolysis. Substantial amounts of titanium and polyethylene wear debris were found in the surrounding tissues. Multiple sources of this debris were found as well as detachment of titanium fiber-mesh pads from the body of the femoral stem.

Adult↗
PubMed1993

A new model to test platelet adhesion under dynamic conditions. Application to the evaluation of a titanium nitride coating.

In order to evaluate under dynamic circumstances the in vitro platelet adhesion induced by rigid materials such as ceramic coatings deposited on selected substrates, a new model simulating a tube has been designed. In vitro platelet adhesion was assessed with this new model: the material was titanium nitride (TiN) deposited on Ti6A14V (TA6V) titanium alloy by a physical vapor deposition (PVD) process. The results were compared to those obtained with complete titanium carbide (TiC) graphite tubes coated with TiN by a chemical vapor deposition (CVD) process. The difference observed (less than 25%) in favour of the new system, could be due to the better surface state of the construction materials of this system. In fact it is a systemic error. However TiN confirms its good performance as a blood-contacting biomaterial.

Alloys↗
PubMed1993

Magnetic resonance imaging evaluation of the spine with metal implants. General safety and superior imaging with titanium.

We studied the cases of 15 patients who underwent postoperative magnetic resonance imaging evaluation after being treated with metal spinal implants. Spine stabilization was required in traumatic injuries for eight patients, cancer destruction in four patients, late cervical subluxation in one patient, spondylosis in one patient, and spondylolisthesis in one patient. A variety of stainless steel and titanium spinal implants were used. The images were evaluated for spinal and implant positioning and artifact production. Both stainless steel and titanium implants were imaged safely and there was no evidence of implant migration of local tissue-heating effect. The titanium spinal implants allowed postoperative spine imaging without the significant image distortion characteristic of the stainless steel implants. The stainless steel implants created significant artifact that impaired the usefulness of the magnetic resonance imaging evaluation.

Adult↗
PubMed1996

Characterization and canine bone tissue reaction of hydroxyapatite-coated titanium using thermal decomposition method.

Hydroxyapatite (HA)-coating by plasma spraying technique, which has been the common method used for HA coating, is not useful for coating the surfaces of porous metal implants because of difficulty in producing a homogeneous HA coating layer less than 30 micrometers. A new coating method, thermal decomposition, has been developed to obtain a dense coating layer with a thickness of 5 micrometer. In this study, the phase composition, surface morphology and adhesive strength between the coating layer and titanium substrate were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and tear-off testing, respectively. The biocompatibility of the implant prepared using this coating technique was compared with that of implants obtained using the plasma spraying technique or uncoated titanium following implantation into canine femurs. Bonding strength between the bone and implant was evaluated by pull-out testing. New bone formation was observed by light microscopy and SEM. The dense coating layer obtained by thermal decomposition ,method was found to be composed of well-crystallized HA on XRD and SEM, and exhibited high adhesive strength. The biocompatibility of the samples obtained using this coating method was superior to that of the uncoated titanium implants and comparable to that obtained using the plasma spraying technique. The thin coating layer obtained using the thermal decomposition method should be useful for coating porous implants.

Animals↗
PubMed1996

Influence of materials for fixation implants on local infection. An experimental study of steel versus titanium DCP in rabbits.

Resistance to infection may be influenced by foreign bodies such as devices for fracture fixation. It is known that stainless steel and commercially-pure titanium have different biocompatibilities. We have investigated susceptibility to infection after a local bacterial challenge using standard 2.0 dynamic compression plates of either stainless steel or titanium in rabbit tibiae. After the wounds had been closed, various concentrations of a strain of Staphylococcus aureus were inoculated percutaneously. Under otherwise identical experimental conditions the rate of infection for steel plates (75%) was significantly higher than that for titanium plates (35%) (p < 0.05).

Animals↗
PubMedDate not supplied

Eight-year clinical retrospective study of titanium plasma-sprayed and hydroxyapatite-coated cylinder implants.

A total of 1,202 press-fit cylinder implants were placed in 479 patients from March 1986 to March 1994. The patients' ages ranged from 14 to 88 years. The implants included 889 titanium plasma-sprayed implants and 313 hydroxyapatite-coated implants. There were no statistically significant differences in the distribution of hydroxyapatite-coated and titanium plasma-sprayed implants based on implant location, type of restoration, age, and sex. Although differences in long-term success rates based on simple percentages were also not statistically significant, cumulative survival rates based on life table analysis up to 96 months were 92.7% for titanium plasma-sprayed systems and 77.8% for hydroxyapatite-coated systems. Graphical interpretations of these data revealed interesting contrasts, including the timing and results of implant failure, which are discussed in detail.

Adolescent↗
PubMedDate not supplied

A comparison of hydroxyapatite-coated Micro-Vent and pure titanium Swede-Vent implants.

This article compares the survival rates of two root-form implants-hydroxyapatite-coated (HA-coated) Micro-Vent and pure titanium Swede-Vent implants-during a 6-year period. A total of 390 implants were placed in 166 patients aged 18 to 81 years. Fifteen implants were lost before prosthesis placement, and one was lost after prosthesis loading. The overall success rates were 96.8% for the HA-coated Micro-Vent implants and 95.2% for the titanium Swede-Vent implants. The survival rates were similar for both the maxilla and the mandible and for the anterior and the posterior areas. Although most of the HA-coated implants were generally placed in types III and IV bone, results indicated that the survival rate was similar to that of pure titanium implants, which were placed more often in types I and II bone.

Adolescent↗
PubMedDate not supplied

Mechanical properties of titanium connectors.

The tensile mechanical properties of welded titanium joints were studied, and intact titanium was used as controls. Welded joints were fabricated with either a stereographic laser-welding technique or a gas tungsten arc welding technique. The effect of heat treatment following a simulated porcelain application was also investigated. Heat-treated laser welds had significantly lower ultimate tensile strengths. Heat treatment had no effect on the modulus of elasticity or elongation, but generally significantly decreased the yield strength of the titanium specimens. The gas tungsten are welding specimens had significantly higher yield strengths and elastic moduli than the other two groups. The elongation of the control specimens was significantly greater than the elongation of the gas tungsten arc welding specimens, which was in turn significantly higher than that of the laser-welded specimens.

Analysis of Variance↗
PubMed1996

[Tonoko pneumoconiosis with deposition of titanium].

A 56-year-old man had worked as a furniture painter and had been exposed to tonoko polishing powder for 30 years. He had complained of dyspnea on exertion for 7 years, and was admitted to our hospital in 1991. A chest X-ray film revealed large opacities and emphysematous changes in both lung fields. Tonoko pneumoconiosis was diagnosed after transbronchial lung biopsy. Home oxygen therapy was given because of progressive hypoxemia, but the patient died of respiratory failure. At autopsy, examination of the lungs showed severe emphysematous changes, and collapse of alveoli. Many gray masses resembling coating cement were seen especially in the upper lobes. Microscopical examination showed that the large opacities were composed of hyaline nodules, similar to silicotic nodules, with anthracosis. Scanning electron microscopy with X-ray microanalysis revealed a high concentration of titanium in the gray mass. A low dose of titanium would not be expected to induce fibrotic changes in the lung, but a high dose and long-term exposure might have that effect. Titanium contained in paint might have exacerbated tonoko pneumoconiosis in this patient.

Dust↗
PubMed1996

Ion implantation and thermal nitridation of biocompatible titanium.

Nitrogen implantation and thermal nitridation processes are investigated to improve the wear resistance of titanium medical devices. Ion implantation uses 80 keV nitrogen ions and doses ranging between 1 x 10(17) and 5 x 10(17)/cm2 to modify the surface layers up to 140 nm depth. Stable surface layers are obtained at high ion doses by post-annealing at 550 degrees C for 30 min. Thermal processes are developed as a function of the time (20-90 min) and annealing temperature (950-1100 degrees C) in a dry nitrogen atmosphere. The amount of titanium nitride formed during the thermal process increases with the annealing temperature and time. Samples are analysed by Rutherford Backscattering Spectroscopy (RBS), Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). Ion implantation and thermal nitridation processes increase the surface hardness and wear resistance improving the mechanical properties of titanium used for movable devices for total joint replacements, such as the hip and knee protheses.

Alloys↗
PubMedDate not supplied

A custom titanium implant-retained single-tooth restoration: a clinical report.

Titanium is an inexpensive metal that can be used to create custom cast restorations. Although special investment and casting equipment is needed to make titanium castings, the potential benefit of inexpensive, biocompatible, and custom restorations is significant. Porcelain can easily be applied to titanium with excellent bond strength and esthetics. Problems associated with casting roughness and fit can be corrected using electrical discharge machining. A method of diagnosis and treatment planning that evaluates the restorative space prior to implant placement and eliminates the use of machined components is presented.

Biocompatible Materials↗
PubMed1997

MR parameters for imaging titanium spinal instrumentation.

The presence of stainless steel implants along a spinal column causes extreme distortion of data collected by magnetic resonance (MR) imaging. The recent availability of titanium alloy spinal instrumentation systems suggests that MR imaging evaluation of the instrumented spine may now be feasible. The objective of this study was to perform MR imaging examinations on spines implanted with titanium alloy instrumentation and to determine the parameters that yield the highest quality images with the least amount of artifact. A titanium pedicle screw construct was implanted into the lumbar spine of two fresh human cadaveric specimens. Sequential spin echo MR scans were performed using various TE and TR ratios on each intact specimen. The resultant images were quantitatively graded for clarity of adjacent soft tissue and osseous structures. Excellent T1- and T2-weighted images with well-defined neural structures were obtained with minimal artifact. The optimal T1-weighted image was obtained with TE = 16 and TR = 500-600, whereas the optimal T2-weighted image was obtained with TE = 60 and TR = 1,300-1,600. By using appropriate settings, high-quality MR scans in both the T1- and T2-weighted modes can be obtained with minimal metal artifact.

Artifacts↗
PubMed1996

Human gingival fibroblast migration promoted by platelet-derived growth factor on titanium is correlated with release of urokinase type plasminogen activator.

The purpose of this study was to examine if the migration of human gingival fibroblasts on titanium was promoted by platelet-derived growth factor (PDGF) and whether the release of urokinase-type plasminogen activator (uPA) was correlated with it. The migration of the fibroblast on titanium was significantly promoted by PDGF in a wound healing assay (p < 0.001). The promotive effect was inhibited by aprotinin, a serine protease inhibitor used for the inhibition of uPA (p < 0.001). The conditioned medium when fibroblast migration was promoted contained a higher concentration of uPA than did that of the control. These results indicated that the promotive effect of PDGF on the migration of human gingival fibroblasts on titanium was correlated with the release of uPA from the fibroblasts.

Aprotinin↗