Titanium as a biomaterial for ossicular replacement: results after implantation in the middle ear of the rabbit

The middle ear poses unique challenges when finding suitable materials for ossicular reconstruction, primarily because of its link to the external environment via the eustachian tube and, hence, its greater exposure to infectious agents. In this study, the biocompatability of titanium was examined in the middle ear of rabbits by using light and scanning electron microscopy. Implants were placed as middle ear prostheses or as free implants. These were inspected at 28 days, 84 days, 168 days, 336 days and 504 days following implantation for mucosal coverage, percent epithelization and any sign of foreign-body reaction. After 28 days, the prostheses were covered by regular mucosa. Although a majority of the free implants took up to 336 days for complete epithelialization, some of the free implants were not epithelialized even at day 504. There were no inflammatory cells observed on the surface of the material, nor were unusual amounts of fibrous tissue seen. In addition, the titanium material exhibited an affinity toward bone. The results of this animal experiment indicate that titanium is a favorable material for ossicular replacement prostheses.     

Replacement of ear ossicles with titanium prostheses

BACKGROUND: Titanium has been a well established implant material for many years. New material processing techniques now permit the manufacture of small implants for ossicular chain reconstruction. METHODS: Between November 1994 and September 1995, 100 titanium middle ear implants (55 PORP, 45 TORP) were used for reconstruction of the ossicular chain. A range of five different sizes for partial and total protheses suits all implantation needs. The shape of the implants can be altered by bending. Time consuming intraoperative shaping and trimming is avoided. RESULTS: At a follow-up time of three months (33 patients) and six months (17 patients), no adverse reactions or extrusions occurred. Biologic fixation between the foot of the partial prothesis and the head of the stapes was found eight months after implantation. A hearing result of 0-20 dB residual air-bone gap was achieved in 79%. CONCLUSION: Titanium middle ear implants show good bio-compatibility and are readily integrated into the ossicular chain. Although delicate in shape, they offer excellent mechanical properties in respect to sound conduction and implantation. Initial results show Titanium to be a perfect implant material for middle ear prostheses, although long-term results are not yet available.     

Tissue reactions to glass ceramics in the middle ear

The bioactive glass ceramic "Ceravital" was used to fashion prostheses for the replacement of various ossicles in the middle ear. They were tested in 70 rabbit ears, where they were accepted in osseous areas without formation of surrounding fibrous tissue. Histological examinations regularly showed an osseous bond with the surrounding bony tissue. Mucous membrane covered these ossicular chain prostheses and showed no evidence of inflammatory reactions. Glass ceramic implants were also used to reconstruct the ossicular chain and the posterior wall of the outer ear canal in 100 patients. The functional results were satisfactory in all cases.     

Plasti-pore implants in middle ear surgery

Plasti-pore, a high-density polyethylene sponge, was one of the earliest biocompatible materials developed specifically for implantation in the middle ear. It is one of the most nonreactive materials known when tested in simulated biochemical exposure to pseudoextracellular fluid. The two basic prosthetic designs are the total ossicular replacement prosthesis and the partial ossicular replacement prosthesis. Plasti-pore implants have now been used for 20 years and are widely accepted by otologic surgeons. The basic properties of the material, implant design, and surgical techniques involved using these prostheses are reviewed in this article.     

Implantation of electromagnetic ossicular replacement device

Semi-implantable hearing aids consisting of permanent middle ear implanted magnet, either partial ossicular replacement prostheses (PORP's) or total ossicular replacement prostheses (TORP's) driven by an electromagnet placed in the ear canal have been tested on six patients undergoing surgery for chronic otitis. The surgical and audiological problems are described. The audiological results were excellent in all six cases. A functional gain of 40-70 dB can be obtained for entire frequency range of the audiogram.     

钛及钛合金人体植入材料研究进展

钛及其合金因其具有低密度、高比强度、低弹性模量、良好的生物相容性和耐蚀性等特点, 被认为是一种理想的人体植入金属材料, 广泛应用于骨关节替换、牙齿修复等方面, 且对其的需求量快速增长; 同时, 钛也存在骨整合率低、抗菌性差、耐磨性差等缺陷, 急需进一步研究和改进。本文介绍了钛及钛合金作为人体植入材料的优异特性, 概述了国内外关于新型β型钛合金、表面改性钛合金、多孔钛合金、钛-陶复合材料的研究进展, 总结了钛及钛合金材料存在的一些问题, 为新型钛及钛合金材料的设计研发, 钛及钛合金综合性能的优化, 钛及钛合金使用寿命的延长提供参考。     

我国钛资源分布和生产现状

钛及其合金具有比强度高、耐蚀性能优、生物相容性好等优点，是一种战略金属，主要用于航空、航天、航海等先进装备。钛白粉是一种重要的化工原料。人造金红石高钛渣、天然金红石等富钛料是生产钛白粉电焊条和海绵钛的原料。本文概述了我国钛矿物的地理分布和由钛原矿到海绵钛的生产工艺，并与国外技术进行了对比说明。介绍了我国钛精矿、富钛料的产能、生产现状和国内需求情况。     

Proplast implants used in otology and in facial reconstructive surgery

Proplast, a self-stabilising alloplastic material, was evaluated in ear surgery and in facial reconstructive surgery. Proplast implants were used on 33 patients to reconstruct the ossicular chain (total or partial ossicular replacement prosthesis), or to rebuild the mastoid cavity. The lack of extrusion over a 24-month period is encouraging. In facial reconstructive surgery 11 patients received Proplast implants to augment and restore facial contours. Contamination with saliva remains a problem, owing to the high porosity of Proplast, which could harbour infection. When Proplast was sterile when implanted, no extrusion appeared over a 12-month period. Although the patients presented here were followed up for a relatively short time, they provide reason for some optimism that the vexed question of alloplastics applied in the field of ear, nose and throat surgery may be solved.     

Immunodiffusion and immunohistochemical investigations on the reactivity of oxide ceramic middle-ear implants

Oxide ceramic materials (partial and total ossicular replacement prostheses) have been implants of preference for the reconstruction of the ossicular chain because of their excellent biocompatibility. The reaction on the surface of the implants takes place at three biodynamic levels according to the model of Stern's bilayer. We investigated the adsorption of proteins, which is determined by the cellular reaction and degradation to the surface using radial immunodiffusion and immunohistochemical methods. First, ceramic implants of aluminum oxide, hydroxyapatite, glass ceramic and zirconium oxide have individual actual (i.e. biological) surfaces. With a perthometer and the contact-free laser Focodyn method we determined each actual (i.e. biological) surface of the various ceramic implants mentioned above. Using radial immunodiffusion, the adsorption of albumin, glycoprotein, plasminogen, fibronectin, IgA, IgG and IgM shows characteristic rates of adsorption to the respective ceramic surfaces in correlating to the actual surface. A cross-check with fluorescent antibodies confirmed the protein adsorption. The individual surface adsorption of the proteins remains characteristic and is the basis for the recording of cellular reactions after implantation.     

Decalcified, lyophilized, sterile heterotopic porcine ossicular xenografts. Experimental evaluation in the guinea pig

Using the guinea pig middle ear model, we assessed decalcified, lyophylized, sterile heterotopic porcine ossicular xeno-implants based on a histology (optic and electron scan microscope) and immunologic (immunofluorscence) methods. Implants were placed in the middle ear and others in the dorsal subcutaneous area. Allo-implants were compared as controls. Implants were placed in the middle ear in 54 animals and skin implants in 14. Under the influence of BMP, the implant ossified in all cases in the middle ear. Intense immune recruitment was not observed. Inversely, there was a mononuclear infiltration reaction to the skin implants with formation of a fibrous capsule, immunoglobulin and complement influx and consequently sequestration. The allo-implants were partially reossified. These findings confirm the value of decalcification with hydrochloric acid for BMP induction, independent of species and the failure of attempted immune despecification. Implant outcome is not dependent on its antigen load, which is high compared with its weight, but on the site of implantation. The middle ear appears to be a privileged site of implantation.     

Titanium and bioactive glass-ceramic coated titanium as materials for keratoprosthesis

The current problem with keratoprosthesis is the ingrowth of corneal or conjunctival epithelium into the anterior chamber. This may lead to infections and extrusion of the prosthesis as well as to the development of retroprosthetic membrane and secondary glaucoma. Glass-ceramic coated and uncoated titanium has been tested as material for the keratoprosthesis to prevent epithelial ingrowth. Twenty-two Supra-Descemet's membrane keratoprostheses were inserted in the eyes of 22 rabbits for 1, 2, 4, 8, or 12 months. The prosthesis had an optic part made of polymethylmetacrylate (PMMA). The support for the optic part and the flange of the prosthesis were made of titanium. Eleven of the prostheses were coated with glass-ceramic. The histological sections of the enucleated eyes were prepared through the central part of the cornea and the prosthesis using a cutting-grinding method. The histological analysis was made on both halves of the implants separately giving two analysis areas in each eye. All 11 titanium prostheses were retained for the time period planned. Two glass-ceramic coated prostheses were lost at 2 and 4 weeks, respectively. This was caused by difficulties at surgery due to a thick coating. These eyes were excluded from the histological analysis. No significant ingrowth of epithelium was seen in 15/18 (83%) and in 16/22 (73%) of the analysed areas of the glass-ceramic coated and titanium prostheses, respectively. Titanium appears to be a suitable material for the keratoprosthesis. The ingrowth of the epithelium may be hindered further by coating the titanium with bioactive glass-ceramic.     

Ossicular coupling of an implantable hearing aid transducer using an Er:YAG laser

Special coupling devices made of pure gold or titanium have been developed to connect a new implantable hearing aid transducer (Tübingen implant) to the ossicular chain. They allow piezotransducer probe-tip connection to the long process of the incus or the stapedial head. Similar to the design of conventional PORPs (partial ossicular replacement prostheses), the coupling devices can be fixed at the ossicular chain, e.g., with the eye loop of stapedial piston prostheses or the bell element of golden wire PORPs. A crimp technique allows connection between coupling device and transducer probe tip [5]. The main disadvantage in connecting the long process of the incus or the stapes having is to drill a dorsal tympanotomy in the posterior wall of the ear canal during surgery. The short distance between tympanotomy and N. facialis contains serious surgical risks. To avoid the risk of facial paralysis, Fredrickson's alternative coupling technique for the body of the incus is investigated in this paper [2]. In this case, the transducer probe tip will be positioned to the incus body and placed on its surface with controlled elastic displacement of the ossicular chain. The simple direct attachment of the probe-tip end on the surface of the incus, however, will not guarantee a stable long-term connection. Thus, by creating a conical, 0.5-to 0.7-mm-deep hole in the incus, the probe tip will be fitted much better. With a novel surgical Erbium-YAG laser this can be done in a contactless procedure. In this paper, first results of microsurgical laser applications with human temporal bones will be shown.     

Tragus perichondrium-cartilage island transplant in middle ear surgery. Method and results after 5 years

Temporalis fascia remains the most widespread material for reconstructing the tympanic membrane in tympanomastoid surgery. If total or partial ossicular replacement prostheses are needed or pathology of the eustachian tube causes ventilation impairment, a more rigid transplant material is required. Between 1989 and 1994 perichondrium-cartilage composite grafts were used in a series of 597 cases of tympanomastoid surgery performed at the University ENT Clinic of Würzburg. The graft was taken from the tragus and prepared as a cartilage island with perichondrium attached to one side, the perichondrium-cartilage island transplant (PCI). If reconstruction of the ossicular chain was necessary, glass ionomer cement protheses (IONOS) were used. Closure of the tympanic membrane could be achieved in 90% of all cases. In those cases where ossicular chain reconstruction was postponed to a second procedure, closure of the drum was achieved in 96%. The audiological results of the different type III procedures were evaluated. By using the PCI technique a favorable closure of the air-bone gap to 10-25 dB was achieved, even in cases with advanced ear pathology technique and results are presented in detail.     

The use of implant-supported titanium prostheses for treatment of periodontally compromised patients including functional and orthodontic therapy. Report of 2 cases

Due to its corrosion resistance and biocompatibility, titanium appears to be an alternative material for implant-supported restorations. However, due to technological difficulties, the clinical application of titanium in implant restorations has been limited. Only after recent progress in technology could the clinical use of ceramo-metal titanium restorations be recommended. The therapeutic repertoire for treating patients with missing teeth has been significantly expanded by modern implant methods. Osseointegrated prostheses have become an integral part of restorative therapy also for periodontally compromised dentitions. This article presents 2 case reports for the use of ceramo-metal implant-supported titanium cast prostheses for restorative treatment of periodontally compromised patients requiring comprehensive treatment involving periodontal, functional, orthodontic and prosthodontic therapy. Favourable clinical results have been obtained and a complication-free service of these reconstructions has been documented throughout a 12- to 24-month observation period. These observations suggest that implant-supported ceramo-metal titanium prostheses may be a valuable part of restorative therapy for periodontally compromised dentitions in that they facilitate restorations with optimal biocompatibility. However, controlled clinical studies are needed to establish the long-term serviceability of these titanium restorations.     

Hypnotic susceptibility order effects in waking analgesia

OBJECTIVE: To develop a measuring apparatus that has the ability to sweep both frequency and external auditory meatus static pressure and can display measurement results in a three-dimensional expression. To measure the middle ear dynamic characteristics of normal-hearing subjects and of patients with this apparatus. DESIGN: Investigate 275 ears of 153 normal-hearing subjects and 72 ears with middle ear diseases. RESULTS: The measurement results show fairly distinctive patterns depending on the middle ear conditions, i.e., normal, ossicular chain separation, ossicular chain fixation, secretory otitis media, tympanic membrane perforation, and tympanic membrane atelectasis. The evaluation of patients with ossicular diseases revealed that the rate of correct diagnosis of ossicular chain separation is 84% and that of ossicular chain fixation is 74%. These diagnoses were confirmed by surgery. CONCLUSION: Displaying the measurement results in a three-dimensional expression is helpful to make correct diagnosis in clinical practice. It is especially easy to make a distinction between the ossicular chain separation and ossicular chain fixation. Therefore, it is concluded that this apparatus has a high degree of clinical applicability to the diagnosis of these diseases.     

Synthesis of Fine Titanium Powders Via Solution Route

Abstract

Titanium, because of its light weight, high specific strength, corrosion resistance and biocompatibility is a demanding material for aerospace, chemical processing industries and biomedical applications. Titanium powders produced from titanium sponge, hydride-dehydride processes and by a variety of centrifugal atomisation techniques from liquid metals are relatively coarse. If fine size titanium powders can be produced, then the grain size in the sintered titanium will be small thereby contributing to the high strength of the product. In the present investigation, an attempt has been made to synthesize fine titanium powders from titanium dioxide. The later is allowed to form a complex, titanium catecholate, in the presence of ammonium sulphate and concentrated sulphuric acid. The complex is filtered, washed with cold isopropyl alcohol and dried. Titanium hydride is prepared by heating the titanium catecholate in the temperature range 500-600°C in hydrogen atmosphere. The powder obtained is crushed ground and reheated at temperatures upto 950°C in vacuum. The product is rapidly cooled from this temperature to obtain titanium powders. The powder characteristics such as particle size and crystallization have been evaluated and these results are reported and discussed.     

Biocompatibility of fixation materials in the brain

Recent clinical reports documenting passive intracranial translocation of microplates and microscrews have prompted concerns regarding brain biocompatibility and neurotoxicity of fixation hardware used in craniofacial surgery. Although the effects of commercially pure titanium. Vitallium (cobalt-chromium-molybdenum), stainless steel, and various alloys have been well assessed in bone and soft tissues, there are no comprehensive studies of these materials in the brain. To investigate this, the biocompatibility of titanium, vitallium, and 316L stainless steel was evaluated in the rabbit brain and compared with silicone elastomer shunt tubing, a material that is used commonly as a neurosurgical implant material with well-established brain biocompatibility. Forty-eight juvenile New Zealand White rabbits were randomly assigned to one of three groups and underwent placement of either commercially pure titanium microscrews, vitallium microscrews, or 316L monofilament stainless steel wire into the parietal region. Silicone elastomer strips of similar size were implanted in the contralateral hemisphere of each rabbit. Animals were assessed daily for signs of neurotoxicity. Rabbits in each group were sacrificed at 2, 4, 8, and 26 weeks following implantation. Brains were sectioned at the implantation site and were examined by means of standard hematoxylin and eosin stains and with immunohistochemical markers sensitive to inflammatory changes in the brain. None of the animals showed any behavioral changes or neurologic deficits suggestive of either systemic or localized toxicity from the implant materials. Silicone clastomer was found to cause the least amount of inflammation relative to other materials tested at all sacrifice points, suggesting that as a standard neurosurgical implant material, it is an appropriate control for studies of brain biocompatibility. At 2 weeks, titanium was found to cause the largest inflammatory response in surrounding brain parenchyma based on analysis of markers for microglial proliferation, gliosis, and leukocyte infiltration. At the 26-week endpoint of our study, the biocompatibility of titanium was nearly equal to the biocompatibility of vitallium based on all studied markers of inflammation. A progressive increase in the inflammatory response surrounding stainless steel implants was noted at 8 and 26 weeks. Relative to all materials studied, at 26 weeks the greatest leukocyte response was found with stainless steel implants. Our results indicate that at the 26-week end-point of our study, titanium and vitallium incited a similar inflammatory response in the rabbit brain that was greater than the response found with silicone elastomer, a standard neurosurgical implant material, but less than that found with stainless steel wire, which is commonly recommended as an alternative fixation material.     

Changes in photon dose distributions due to breast prostheses

PURPOSE: Subcutaneous prosthetic implants had been routinely used for cosmetic augmentation and for tissue replacement following mastectomy over the last 15 years. The implants come in many forms as the gel filler material and surrounding shell material(s) vary significantly. METHODS AND MATERIALS: This study uses a thin window parallel-plate chamber and thermoluminescent dosimeters to quantify and dosimetric changes to surrounding breast tissue due to the presence of the prosthesis. A mammographic phantom was compared to four commercial prostheses, namely two silicon gel fillers within two different shells (silicon or silicon/polyurethane), a tri-glyceride within silicon and a bio-oncotic gel within silicon/polyurethane. The latter two implants were designed with a low-Z fill for diagnostic imaging benefits. RESULTS: Ion chamber results indicate no significant alteration of depth doses away from the implant with only minor canceling (parallel opposed) interface perturbations for all implants. In addition the physical changes to the irradiated prostheses were quantified by tonometry testing and qualified by color change. Each implant exhibited color change following 50 Gy, and the bio-oncotic gel became significantly less formable following irradiation, and even less formable 6 weeks postirradiation. CONCLUSION: The data indicates that prostheses do not affect the photon beam distribution, but radiation does affect the prostheses.     

外科植入物用钛合金的表面改性

钛合金作为外科植入物用材料在临床上得到了越来越多的应用。综述了钛合金作为外科植入物的优良性能及国内外在钛合金表面改性方面的发展和研究现状。阐述了表面改性对改善钛合金的耐磨性，耐蚀性和生物学性能方面的重要作用。分析表明：开发新型钛合金和寻求理想的表面改性工艺来获得高质量的涂层或将生物活性相添加到钛合金基体中制备成复合材料是提高钛合金生物学性能的有效途径。     

Adjusting the geometry of implantable hearing aid components to human temporal bone. II: Microphone

Prerequisite to implantation of a piezoelectrical transducer of an implantable hearing aid is a shape allowing its implantation into human mastoid and middle ear. To approach this problem, a consecutive series of six transducer prototypes was created in an iterative process. Their functional geometry was evaluated in 50 human temporal bones. A shape for a functioning transducer was found which will enable implantation in 78% of the cases examined (confidence interval: 61.5%-89.2%). It will allow simultaneous implantation of the transducer into the mastoid and microphone, which is situated transmastoidal in the posterior wall of the ear canal. Furthermore, the transducer may be coupled to the ossicular chain or the perilymph.