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PubMed2000

[Pure titanium as bone substitute. Geometric and substance-specific aspects of computer-assisted fabrication and follow-up imaging].

Computer-assisted prefabricated skull implants of pure titanium as a bone replacement material have been used in 22 departments since 1994. Our experience with 104 implants includes clinical aspects (indication; tissue quality; surgical technique; patient guidance), but also geometric and material-specific parameters (acquisition, transfer, and evaluation of CT data; construction; manufacturing; cleaning; postoperative use of radiologic techniques). While the clinical aspects are responsibly defined by the respective surgeon, the geometric and material-specific parameters of individual implants have to comply with the laws on medical products. Therefore, the prospective documentation for each implant includes: helical CT acquisition parameters; geometric data of the computer-based skull model and implant; the cleaning procedure; and the individual marking. Medically specified pure titanium is processed by milling only so that neither purity nor structure is impaired. A specially developed milling technique guarantees the fabrication of all constructed elements down to fine details of 50 microns. Considering the necessary radiologic follow-up of defects after tumor surgery, all patients in our hospital undergo postoperative MRI examination, partly with preoperative documentation as an intraindividual control. Such comprehensive documentation and quality assurance is essential for techniques of prefabricated bone substitution. Hand in hand with scientific research and clinical application, these formal criteria have to be elaborated and fulfilled for the respective techniques. The successful determination of specifically adapted MRI sequences goes even one step further: spin-echo sequences minimize inhomogeneities of the magnetic field induced by the titanium implants and enable accurate postoperative documentation and diagnostics especially in the follow-up after tumor surgery.

Bone Substitutes↗
PubMed2005

The anchorage quality of titanium microplates with short microscrews for orthodontic anchorage applications.

AIM: The aim of this clinical study was to assess the stability of titanium microplates with short microscrews for orthodontic anchorage applications. MATERIAL AND METHODS: Eleven titanium microplates with short microscrews were implanted in nine patients for unilateral gap closure, and in one female patient with severe periodontal problems of the dentition for bilateral gap closure. After a healing period of 2-3 weeks the microplates were loaded with directly applied forces (150/200 cN). RESULTS: All implanted microplates were clinically and radiologically stable. On explantation all microplates were firmly anchored in the buccal cortical bone. CONCLUSIONS: To summarize, we have determined that titanium microplates with short microscrews meet all the requirements for osseointegrated anchorage. Furthermore, they have the advantage that the points of insertion in the upper and in the lower jaw can be very freely chosen without the risk of damaging adjacent anatomical structures.

Bone Plates↗
PubMed2006

[Variable length titanium prostheses for type III tympanoplasty. Intraoperative length adjustment and fixation of the cartilage overlay].

INTRODUCTION: For type III tympanoplasty by partial ossicular replacement prosthesis (PORP) or total ossicular replacement prosthesis (TORP), the length of the prosthesis must match the individual intraoperative anatomical and physiological characteristics. MATERIALS AND METHODS: Databanks were used to determine the necessary sizer length of the sizer disc. The measurement template for the size of the cartilage to overlay the prosthesis headplate was derived from the headplates of the Tübinger titanium prostheses (TTP) and the Dresdener titanium prostheses. Finally all functions were integrated into a synthetic plate. RESULTS: The result was a simple and reasonably priced disposable multifunctional instrument (Tübinger sizer disc TSD) which allowed an exact measurement for every prosthesis in TORP and PORP. For the TTP-Variac, the TSD enabled the simple intraoperative production of prostheses with the length desired by the surgeon. For PORP the TSD enabled an adaptation of the diameter of the prosthesis foot for TTP, TTP-Vario and TTP-Variac and provided a template for the size determination of the cartilage overlay of the titanium prosthesis head. The sizers and the resulting prostheses were used for initial tympanoplastic operations. Audiometric investigations carried out 6 weeks postoperatively gave results corresponding to those previously obtained in a study with TTP and TTP-Vario using the old instrumentation. CONCLUSIONS: The new instrumentation leads to an improvement of the intraoperative practicability and a simplification. The audiological results remain the same.

Disposable Equipment↗
PubMed2004

[Titanium deposits on the ceramic heads of dislocated total hip replacements].

INTRODUCTION: In cases of revision total hip replacement (THR) having acetabular titanium components with dislocations in the past, metallic deposits are frequently found on the ceramic heads. The aim of this study was to determine whether the metallic deposits increase surface roughness in definite areas. MATERIALS AND METHODS: Ten ceramic heads of revised THR which showed metallic deposits were investigated. The patients suffered from one to six dislocations. The prosthesis lifetime ranged from 2 weeks to 12 years. Surface structure was investigated in a scanning electron microscope (LEO 1525), and the metallic deposits characterised by means of energy dispersive x-ray analysis (EDX). RESULTS: In the area of the metallic deposits, titanium was detected by EDX. Edges with a significant increase in surface roughness were observed, partially accompanied by damage to the surface structure and loosening of Al(2)O(3) particles. DISCUSSION: Titanium deposits increase surface roughness in definite areas, which probably causes wear to the ceramic-ceramic or ceramic-polyethylene articulations due to different roughness values and surface properties. Further investigations are necessary in order to determine the importance of these findings with respect to wear and loosening of total hip arthroplasty.

Aged↗
PubMed2005

[HAC-titanium as an implant for interbody fusion in spinal canal stenosis of the cervical spine. Six-year clinical trial].

A total of 102 patients were operated on in 134 levels because of an isolated spondylotic cervical stenosis in 6 years. A titanium implant coated with hydroxyapatite ceramic (HAC) was inserted. The average age of the patients was 53 years. The final clinical and radiological follow-up was performed after 15 months. The functional outcome was classified as good to excellent (Odoms's score) in 83.8% of the patients. Implant-related complications requiring revision surgery included two dislocated dowels and one vertebral collapse in a bisegmental operation. After 6 weeks beginning of bony growth around the implant was seen in 38% of all inserted titanium cages on roentgenograms. A complete solid bony incorporation was shown in 91.2% of the fused segments after 6 months and in 96% after 12 months or at follow-up, respectively. These results illustrate the efficacy of the easy to handle HAC titanium implant, demonstrating that this technique achieves good clinical outcome with the same complication rate as comparable techniques.

Adult↗
PubMed1997

[Safety aspects in the coating of titanium slide components].

Due to the ever increasing percentage of patients who suffer from allergies and need joint replacements, it is necessary to also consider using titanium for the bearing surface. Hence, the number of coated titanium bearing surfaces for both hips and knees is increasing. It is difficult for the user to evaluate the products already marketed. This paper describes the presently used coating techniques without considering sophisticated technical details but listing the advantages and disadvantages of the various technologies. Using the list of necessary basic investigations for qualifying a coating together with production relevant measures for quality assurance, this paper aims to provide the possibility to get involved with a supplier in a discussion about the suitability of the coated titanium bearing components without regarding the specific technical details.

Alloys↗
PubMed2000

Induction of interleukin-6 release in human osteoblast-like cells exposed to titanium particles in vitro.

Orthopaedic wear debris induces release of bone-resorbing factors from macrophages and fibroblasts. However, the extent to which elemental metallic particles induce bone cells to express factors contributing to implant loosening remains unclear. This study showed that exposure of MG-63 osteoblast-like cells to titanium particles at a concentration of 0.30% v/v resulted in a 15-fold increase in IL-6 release into the culture medium after 24 hours, when compared with cells without particles. Northern blots revealed that exposure of MG-63 cells to titanium particles at a concentration of 0.30% v/v for 24 hours increased IL-6 mRNA signal levels by 9.6-fold, when compared with control cultures. Pretreatment of MG-63 cells with cytochalasin B prevented the particle-induced increase of IL-6 expression but did not alter the basal level of IL-6 release from cells cultured in the absence of particles. The protein kinase C inhibitor, H7, and the serine/threonine kinase inhibitor, genistein, abolished the particle-induced increase in IL-6 release at a concentration of 100 microM for each compound. In contrast, an inhibitor of protein kinase A, HA1004, had no effect on the particle-induced increase in IL-6 release. The transcription factors, nuclear factor IL-6 and nuclear factor kappa B, translocated into the nucleus within 1 hour of particle exposure. This study showed that osteoblast-like cells respond to titanium particles through increased expression of the proinflammatory cytokine, IL-6, in a process requiring phagocytosis and intracellular signaling pathways. These results suggest that osteoblasts play a direct role in implant loosening because of localized release of soluble mediators such as interleukin-6.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2005

Subsidence of titanium straight stems in combination with highly viscous bone cement.

Varying results and a high rate of subsidence have been reported for the straight femoral stem (M.E. Muller) made of titanium alloy. We examined subsidence in 135 titanium-alloy straight stems implanted with high viscosity cement after 68.8+/-11.5 months using a digital high-precision method (EBRA-FCA). One revised implant showed a subsidence of 14.6 mm and another 2.5 mm over 5 years. A third implant without migration was found to be loose. The 122 implants without loosening showed a mean subsidence of 0.1+/-0.1 mm, and focal osteolysis was seen in two. Altogether, we found subsidence of the titanium stems very small. The small subsidence may be related to the use of high viscosity bone cement.

Aged↗
PubMed2001

Increased loosening of cemented straight stem prostheses made from titanium alloys. An analysis and comparison with prostheses made of cobalt-chromium-nickel alloy.

We studied the rate of aseptic loosening of three different types of femoral stems in primary total hip replacement. After a median follow-up of 10.2 years 4/147 CoCrNi (SS77) straight stems (type M.E. Müller) were revised. After a median follow-up of 7.7 years 32/239 Ti-6A1-7Nb (SS77) were revised and after a median follow-up of 5.2 years 52/203 SLS Titanium alloy stems were revised. Whereas the first two stems are of identical design (smooth-blasted, anterior and posterior collar), the SLS stem design is different. Surgical procedure and cementing technique have remained unchanged. There is a significantly higher risk of failure for smaller titanium stem sizes and in males and patients who are physically active. This indicates that the greater elasticity of the Titanium alloy is one of the factors responsible for loosening.

Aged↗
PubMed2002

Biological fixation of hydroxyapatite-coated versus grit-blasted titanium hip stems: a canine study.

BACKGROUND: The purpose of the study was to evaluate the influence of a proximal hydroxyapatite (HA) coating in comparison with a grit-blasted titanium surface of an anatomic hip stem in an animal model over a maximum duration of 2 years. METHODS: Thirty adult dogs underwent implantation of either a proximally HA-coated or a grit-blasted anatomic titanium stem. The animals were clinically evaluated for their walking ability, and serial radiographs were taken. The femora were assessed histomorphologically at set time points from 6 weeks to 2 years postoperatively. Undecalcified thin section specimens through the proximal and distal portion of the coating or grit blasting were prepared. The percentage of implant surface with direct bone contact without connective tissue involvement was determined. RESULTS: Radiographically, animals with uncoated prostheses showed characteristic signs of loosening more frequently. Histomorphometrically, an average of 65% of the surface of HA-coated implants had bone contact, but only 14.7% of the surface of grit-blasted prostheses ( p=0.0001). There was no relationship between bone contact and the duration of implantation of the prosthesis, either for the coated or for the uncoated prostheses. HA coating enhances osseointegration of an anatomic hip stem. CONCLUSION: Anatomic stems with rounded design require a surface coating or surface structure, since the mere grit-blasting of the titanium surface does not ensure osseointegration in this animal model.

Animals↗
PubMed2003

A comparative clinical outcome evaluation of smooth (10-13 year results) versus rough surface finish (5-8 year results) in an otherwise identically designed cemented titanium alloy stem.

BACKGROUND: We retrospectively compared the influence of surface finish with respect to the long-term durability of a cemented titanium alloy stem of the same design but different surface finish. METHODS: From 1984 to 1994, the stem was made of a titanium-aluminum-vanadium alloy. A total of 201 patients with 220 smooth stems (mean follow-up 11 years and 4 months) out of 612 implanted between 1984 and 1987 and 319 patients with 343 rough stems (mean follow-up 5 years and 10 months) out of 812 implanted between 1991 and 1993 could be reviewed clinically and radiologically for comparison. The average age of the patients with the smooth stem was 58.1 years and of the patients with the rough stem, 62.2 years. In both groups, 35% of patients were male and 65% female. RESULTS: The mean Merle d'Aubigné hip score increased from 10.5 to 16.0 points in the smooth stem group and from 11.0 to 16.9 points in the rough stem group. The distribution of radiolucent lines, according to the zones of Gruen, was similar in both groups. The smooth stem required revision in 18 cases after a mean follow-up of 11 years and 4 months and the rough stem in 30 cases after a mean follow-up of 5 years and 10 months. The survival analysis (Kaplan-Meier) revealed 95.4% survival after 13 years for the smooth femoral component and 76.7% survival after 8 years for the rough femoral component. CONCLUSIONS: The implantation of titanium alloy stems with a rough surface finish cannot be recommended because of its high aseptic loosening rate.

Alloys↗
PubMed2004

Cemented titanium stems show high migration: transprosthetic drainage system has no advantage over third-generation cementation technique.

INTRODUCTION: A newly developed cemented titanium stem with excellent laboratory results using a transprosthetic drainage system (TDS) was clinically tried for the first time. Prognostic radiographic methods including migration measurement and clinical investigation were performed for up to 7 years. MATERIALS AND METHODS: Twenty-two patients prospectively and consecutively received total hip replacement using a cemented titanium stem and a threaded Zweymüller cup. Ten stems (CPS) were cemented conventionally with a third-generation cementation technique. In 12 stems (TRIOS) a TDS was used to enhance cement mantle quality. Design of cup and stem was similar in all cases. RESULTS: More than 50% of all stems showed considerable subsidence (>1 mm at 2 years and >2.5 mm at 5 years) and progressive radiolucent lines ( >1 mm at 2 years). Two patients of the TRIOS group had to be revised at 7 years postoperatively. No significant differences were found in radiological parameters (migration, stem subsidence, tilting, occurrence of radiolucent lines) and clinical outcome between the two cementation techniques. All parameters indicate an unfavourable long-term survival. Use of a TDS did not show any significant advantages over the conventional cementation technique. CONCLUSION: It can be concluded that cementing titanium stems of this design cannot be recommended.

Aged↗
PubMed2001

Immunohistochemical characterization of the perivascular infiltrate cells in tissues adjacent to stainless steel implants compared with titanium implants.

Metallic orthopaedics implants are composed of elements that are known to be skin sensitizers in the general population. In this study, we analyzed the cells of perivascular infiltration in the tissue adjacent to titanium (n = 23) and steel (n = 8) implants after explantation of the metals by immunohistochemical methods. The following panel of monoclonal antibodies were used as parameters: CD 1a (Langerhans cells), CD 4 (T-helper cells), CD 8 (T-suppressor cells), CD 11c (monocytes and macrophages), CD 45 RO (memory cells), CD 45 RA (naive cells), eosinophil cationic proteins (ECP), neutrophil elastase, and HLA-DR. The number of perivascular total cells did not differ significantly. All cells were identified in both metal subgroups, but a statistical difference was not seen in the above-mentioned parameters. We conclude that sensitization to metals is possible in the tissue adjacent to steel and titanium implants, because all cells which play an important role in allergic delayed-type hypersensitivity (type IV) reactions are present. This phenomenon may be called a 'pre-sensitization' phase, because no sensitization or allergic reactions were seen in our cases. Second, in the present study, a statistical difference was not seen in the number of infiltrate cells in the tissue adjacent to steel compared with titanium implants.

Adult↗
PubMed1998

The relevance of hydroxyapatite and spongious titanium coatings in fixation of cementless stems. An experimental comparative study in rat femur employing histological and microangiographic techniques.

Pure titanium rods plasma-spray coated with hydroxyapatite (HA) or porous titanium (Ti) of controlled roughness were implanted bilaterally in the distal femur of Sprague-Dawley rats to compare the extent of bone growth on the two types of coating. The relevance of other factors, like mechanical stability and biological adaptation of the bone to the insertion of a foreign body implant, were investigated in femora which were over-reamed (absence of primary fit) or reamed without insertion of the rod. Continuous tetracycline labeling for the first 30 days and for the last 2 weeks in the 90-day group was performed; histological/histometric, fluorescence and microangiographic studies were carried out on serial sections of the implanted and control femora. In the group of stable implants, HA-coated rods showed 90% integration versus 53% with Ti-coated implants (P < 0.001); in over-reamed implants neither surface bone growth nor endosteal fixation occurred, and both types of rods were surrounded by a thick layer of connective tissue. The study documented early adhesion of osteoblasts and direct deposition of bone matrix on the substrate, while on spongious titanium osteogenesis was observed only in proximity to the surface. Remodeling of the reactive, primary bone to mature, lamellar bone took the form of a capsule surrounding the implants and radial bridges connecting the latter to the endosteal surface. The number, height and thickness of these bridges appeared to be the factors determining implant stability, rather than the extent of the bony capsule on the perimeter of the implant. Integration was a function not only of mechanical conditions and surface geometry, but also of the biological response of the whole bone to changes in the vascularization pattern. The reported phenomena can be seen more easily in experimental models involving small rodents because of their fast bone turnover and revascularization, but it is expected that they take place, even at a lower speed, in clinical situations like cementless stems of total hip replacement.

Angiography↗
PubMed2005

Hearing results with the titanium ossicular replacement prostheses.

The purpose was to study the hearing results in patients receiving a Kurz titanium Bell partial ossicular replacement prosthesis (PORP) or an Aerial total ossicular replacement prosthesis (TORP). The study was a retrospective chart review in a tertiary otologic referral center. A computerized otologic database was used to identify 111 patients implanted with either a PORP or TORP prosthesis. Audiograms were reviewed and air-bone gaps were calculated for each patient. The improvement of the average air-bone gap (ABG) was 10.2 and 12.7 dB at 3 and 20 months after ossiculoplasty, respectively. Sixty-six percent of patients (73/111) had a postoperative air-bone gap of 20 dB or less. The ABG for the titanium PORP prosthesis was 14.3+/-9.7 dB, compared with 25.2+/-13.7 dB for the TORP prosthesis (P <0.05). The ABG to within 20 dB or less was obtained in the PORP group in 77% of the cases, versus 52% of the cases in the TORP group (P <0.05). Two extrusions of the prostheses were observed at 17 and 20 months after surgery (1.8%). Revision procedures for functional failure were carried out in 20 patients (18%). The rate of sensorineural hearing loss was 3.6%. The major factors influencing good audiometric results were the surgical procedure preserving the external auditory canal and the presence of the stapes. The best hearing results were achieved when a PORP was used in an intact canal wall (ICW) procedure, and the worst hearing results were achieved when a TORP was used in a canal wall down (CWD) procedure. The titanium Kurz prosthesis has been an effective implant at our institution for ossicular reconstruction.

Adolescent↗
PubMed1998

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.

Animals↗
PubMed2003

Comparison of plain radiographs with CT scan to evaluate interbody fusion following the use of titanium interbody cages and transpedicular instrumentation.

The availability of lumbar interbody cages has fuelled renewed interest in interbody fusion. Despite this, there is no consensus regarding the best non-invasive method for evaluation of interbody fusion, especially where cages have been used. The purpose of this study was to determine whether high-quality thin-slice (1- to 3-mm) computed tomography (CT) scans allow proper evaluation of interbody fusion through titanium cages. Patients undergoing lumbar interbody fusion were prospectively evaluated with CT scan and plain radiographs 6 months following surgery. These images were blindly and independently evaluated by a consultant radiologist and a spine research fellow, for bridging bony trabeculation both through and surrounding the cages as well as for changes at the cage endplate interface. Fifty-three patients (156 cages) undergoing posterior lumbar interbody fusion using titanium interbody cages were evaluated. Posterior elements were used to pack the cages and no graft was packed outside the cages. The outcome data were analysed using the Kappa co-efficient and chi-squared analysis. On CT scan, both observers noted bridging trabeculation in 95% of the cages (Kappa 0.85), while on radiographs this was present in only 4% (Kappa 0.74). Both observers also identified bridging trabeculation surrounding the cages on CT scan in 90% of cages (Kappa 0.82), while on the radiographs this was 8% (Kappa 0.86). Radiographs also failed to demonstrate all the loose cages. The results of the study show that high-quality CT scans show images suggesting bridging bony trabeculae following the use of titanium interbody cages. They also appear to show consistent bone outside the cages in spite of no bone graft having been used, and they appear to be better than plain radiographs in the early detection of cage loosening.

Female↗
PubMed1998

Occipito-cervical fusion using posterior titanium plates.

Occipito-cervical fusion may be indicated for instability of the occipito-cervical junction or atlanto-axial spine secondary to a wide spectrum of pathology. Many techniques exist to stabilize the spine until fusion is achieved. Recent reports of plate fixation have been favorable. In this study we set out to determine the effectiveness and advantages of titanium plate fixation when used to stabilize the occipito-cervical junction. Thirteen patients with occipito-cervical instability or atlanto-axial instability underwent occipito-cervical fusion using posterior titanium plates. The plates were contoured to the occipito-cervical junction and fastened to the skull with screws, and to the spine with lateral mass screws. The patients were followed prospectively clinically and radiographically to a minimum of 24 months. Outcome parameters included peri-operative morbidity and complications, hardware integrity, spinal alignment, fusion, and neurological status. Twelve of thirteen patients went on to solid fusion radiologically and clinically, and recovered or improved from their myelopathy. One patient did not. Three patients had radiographic evidence that two screws were loose and one screw was broken. There were no instances of plate breakage. We conclude that titanium plate fixation of the occipito-cervical junction is versatile and stable. The plates maintain axial correction and allow for future MR imaging.

Adult↗