Release and excretion of metal in patients who have a total hip-replacement component made of titanium-base alloy

Significantly reduced leg length discrepancy and increased femoral offset by application of a head-neck adapter in revision total hip arthroplasty

Head-neck adapters in total hip arthroplasty (THA) promise the reconstruction of optimal femoral offset and leg length in revision THA while retaining stable implants. Radiological parameters after adapter implantation in THA revision were determined in 37 cases. Significant reduction of leg length discrepancy and improvement of femoral offset (P < 0.001) were found. Clinical endpoints were determined in 20 cases (mean follow-up 4.0 years). Clinical scores were rather poor (median Harris hip score 54, WOMAC score 41) due to age and comorbidities, postoperative dislocation occurred in 3 cases. Only one stable femoral stem had to be revised due to recurrent postoperative dislocation. In conclusion, a head-neck adapter can be a valuable tool in certain cases of revision THA with acceptable dislocation rates while allowing the retention of stable implants.

Accurate determination of ultra-trace levels of Ti in blood serum using ICP-MS/MS

Ti is frequently used in implants and prostheses and it has been shown before that the presence of these in the human body can lead to elevated Ti concentrations in body fluids such as serum and urine. As identification of the exact mechanisms responsible for this increase in Ti concentrations, and the risks associated with it, are not fully understood, it is important to have sound analytical methods that enable straightforward quantification of Ti levels in body fluids (for both implanted and non-implanted individuals). Until now, only double-focusing sector field ICP-mass spectrometry (SF-ICP-MS) offered limits of detection that are good enough to deal with the very low basal levels of Ti in human serum. This work reports on the development of a novel method for the accurate and precise determination of trace levels of Ti in human serum samples, based on the use of ICP-MS/MS. O2 and NH3/He have been compared as reaction gases. While the use of O2 did not enable to overcome all spectral interferences, it has been shown that conversion of Ti(+) ions into Ti(NH3)6(+) cluster ions by using NH3/He as a reaction gas in an ICP-QQQ-MS system, operated in MS/MS mode, provided interference-free conditions and sufficiently low limits of detection, down to 3 ng L(-1) (instrumental detection limit obtained for the most abundant Ti isotope). The accuracy of the method proposed was evaluated by analysis of a Seronorm Trace Elements Serum L-1 reference material and by comparing the results obtained with those achieved by means of SF-ICP-MS. As a proof-of-concept, the newly developed method was successfully applied to the determination of Ti in serum samples obtained from individuals with and without Ti-based implants. All results were found to be in good agreement with those obtained by means of SF-ICP-MS. The typical basal Ti level in human serum was found to be <1 μg L(-1), while values in the range of 2-6 μg L(-1) were observed for implanted patients.

Wear debris from hip prostheses characterized by electron imaging

The characterization of wear particles is of great importance in understanding the mechanisms of osteolysis. In this unique study, thirty-one tissue samples were retrieved at revision surgeries of hip implants and divided into four groups according to the composition of metal prosthetic components. Tissue samples were first analyzed histologically and then by scanning electron microscopy (SEM) combined with back-scattered electron imaging and energy dispersive X-ray spectroscopy. Therefore, particles were studied directly in situ in tissue sections, without the requirement for particle isolation. The composition of metal wear particles detected in the tissue sections corresponded to the composition of the implant components. A considerable number of large metal particles were actually clusters of submicron particles. The clustering of submicron particles was observed primarily with CoCrMo (cobalt-chromiummolybdenum) and, to a lesser extent, for stainless steel particles. SEM secondary and back-scattered electron imaging was an appropriate and selective method for recognizing the composition of metal particles in the in situ tissue sections, without destroying their spatial relationship within the histology. This method can be used as a screening tool for composition of metal and ceramic particles in tissue sections, or as an additional method for particle identification.

Chromium level of salvaged blood in patients undergoing revision hip arthroplasty

PURPOSE. To evaluate the chromium level of the salvaged blood in patients undergoing revision total hip arthroplasty (THA). METHODS. Records of 7 women and one man aged 54 to 83 (mean, 64.3) years who underwent revision THA for aseptic loosening of the acetabular component (n=6), osteolysis of the acetabulum (n=1), or migration of the outer head (n=1) were reviewed, as were 2 controls who underwent primary THA. The initial THA entailed a metal-on-metal prosthesis (n=4), a metal-on-polyethylene prosthesis (n=3), and a bipolar head prosthesis (n=1). Chromium levels in the preoperative peripheral blood and intraoperative salvaged blood were measured using atomic absorption analysis. RESULTS. For controls and the patient with a bipolar head prosthesis, the mean chromium level in salvaged blood was 0.4 (range, 0.2-0.6) micrograms/l, which was significantly lower than that in the remaining 7 patients undergoing revision THA (mean, 5.6 micrograms/l; range, 1.2-9.8 micrograms/l). CONCLUSION. Salvaged blood of patients with a metal-on-metal prosthesis undergoing revision THA contained higher levels of chromium.

Vanadium release in whole blood, serum and urine of patients implanted with a titanium alloy hip prosthesis

INTRODUCTION

Vanadium (V) is a minor constituent of the Titanium-Aluminum-Vanadium (TiAlV) alloy currently used in cementless hip prostheses. Present study aimed at verifying the correlation of vanadium levels among different matrices and assessing reference levels of the ion in a population of patients wearing a well-functioning hip prosthesis.

METHODS

Vanadium was measured using Inductive Coupled Plasma Mass Spectrometry (ICP-MS) in whole blood, serum and urine of 129 patients implanted with a TiAlV-alloy hip prosthesis.

RESULTS

The values in the serum were above the upper limit of the reference values in 42% of patients (29% in urine and 13% in whole blood). A good correlation among matrices was observed (p < 0.001). The cohort of patients (N = 32) complaining of pain or in which a loosening or damage to the prosthesis was assessed showed a significantly higher excretion of vanadium in urine as compared with the remaining asymptomatic patients (p = 0.001). The 95th percentile distribution of vanadium in the cohort of patients with a well-functioning prosthesis was 0.3 μg/L in whole blood, 0.5 μg/L in serum and 2.8 μg/L in urine, higher that in the unexposed population, especially for urine.

CONCLUSIONS

The presence of a prosthesis, even though well-functioning, may cause a possible release of vanadium into the blood and a significant urinary excretion. The reference values of vanadium of the asymptomatic patients with titanium alloy hip prostheses supplied information regarding the background exposure level of the ions and their lower and upper limits.

Improving cytocompatibility of Co28Cr6Mo by TiO2 coating: gene expression study in human endothelial cells

Cobalt-based materials are widely used for coronary stents, as well as bone and joint implants. However, their use is associated with high corrosion incidence. Titanium alloys, by contrast, are more biocompatible owing to the formation of a relatively inactive titanium oxide (TiO2) layer on their surface. This study was aimed at improving Co28Cr6Mo alloy cytocompatibility via sol-gel TiO2 coating to reduce metal corrosion and metal ion release. Owing to their role in inflammation and tissue remodelling around an implant, endothelial cells present a suitable in vitro model for testing the biological response to metallic materials. Primary human endothelial cells seeded on Co28Cr6Mo showed a stress phenotype with numerous F-actin fibres absent on TiO2-coated material. To investigate this effect at the gene expression level, cDNA microarray analysis of in total 1301 genes was performed. Compared with control cells, 247 genes were expressed differentially in the cells grown on Co28Cr6Mo, among them genes involved in proliferation, oxidative stress response and inflammation. TiO2 coating reduced the effects of Co28Cr6Mo on gene expression in endothelial cells, with only 34 genes being differentially expressed. Quantitative real-time polymerase chain reaction and protein analysis confirmed microarray data for selected genes. The effect of TiO2 coating can be, in part, attributed to the reduced release of Co(2+), because addition of CoCl2 resulted in similar cellular responses. TiO2 coating of cobalt-based materials, therefore, could be used in the production of cobalt-based devices for cardiovascular and skeletal applications to reduce the adverse effects of metal corrosion products and to improve the response of endothelial and other cell types.

Impact through time of different sized titanium dioxide particles on biochemical and histopathological parameters

Due to corrosion, a titanium implant surface can be a potential source for the release of micro (MPs) and nano-sized particles (NPs) into the biological environment. This work sought to evaluate the biokinetics of different sized titanium dioxide particles (TiO2 ) and their potential to cause cell damage. Wistar rats were intraperitoneally injected with 150 nm, 10 nm, or 5nm TiO2 particles. The presence of TiO2 particles was evaluated in histologic sections of the liver, lung, and kidney and in blood cells at 3 and 12 months. Ultrastructural analysis of liver and lung tissue was performed by TEM, deposit concentration in tissues was determined spectroscopically, and oxidative metabolism was assessed by determining oxidative membrane damage, generation of superoxide anion (O2(-)), and enzymatic and non-enzymatic antioxidants. TiO2 particles were observed inside mononuclear blood cells and in organ parenchyma at 3 and 12 months. TiO2 deposits were consistently larger in liver than in lung tissue. Alveolar macrophage O2(-) generation and average particle size correlated negatively (p < 0.05). NPs were more reactive and biopersistent in lung tissue than MPs. Antioxidant activity, particularly in the case of 5 nm particles, failed to compensate for membrane damage in liver cells; the damage was consistent with histological evidence of necrosis.

Titanium dioxide nanoparticles: a review of current toxicological data

Titanium dioxide (TiO2) nanoparticles (NPs) are manufactured worldwide in large quantities for use in a wide range of applications. TiO2 NPs possess different physicochemical properties compared to their fine particle (FP) analogs, which might alter their bioactivity. Most of the literature cited here has focused on the respiratory system, showing the importance of inhalation as the primary route for TiO2 NP exposure in the workplace. TiO2 NPs may translocate to systemic organs from the lung and gastrointestinal tract (GIT) although the rate of translocation appears low. There have also been studies focusing on other potential routes of human exposure. Oral exposure mainly occurs through food products containing TiO2 NP-additives. Most dermal exposure studies, whether in vivo or in vitro, report that TiO2 NPs do not penetrate the stratum corneum (SC). In the field of nanomedicine, intravenous injection can deliver TiO2 nanoparticulate carriers directly into the human body. Upon intravenous exposure, TiO2 NPs can induce pathological lesions of the liver, spleen, kidneys, and brain. We have also shown here that most of these effects may be due to the use of very high doses of TiO2 NPs. There is also an enormous lack of epidemiological data regarding TiO2 NPs in spite of its increased production and use. However, long-term inhalation studies in rats have reported lung tumors. This review summarizes the current knowledge on the toxicology of TiO2 NPs and points out areas where further information is needed.

Serum titanium, niobium, and aluminum levels after instrumented spinal arthrodesis in children

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

To determine serum titanium, niobium, and aluminum levels in pediatric patients within the first postoperative year after instrumented spinal arthrodesis.

SUMMARY OF BACKGROUND DATA

Instrumented spinal arthrodesis is a common procedure to correct scoliosis and kyphosis. Titanium-based instrumentation is increasingly favored due to enhanced biomechanical properties, but concerns have arisen regarding metal debris release and the potential for local and systemic complications.

METHODS

The pattern of systemic metal release over time was evaluated by measuring serum titanium, niobium, and aluminum levels preoperatively and 1 week, 1 month, 6 months, and 12 months after instrumented spinal arthrodesis using a titanium alloy. Serum metal levels were measured using high-resolution inductively coupled plasma mass spectrometry.

RESULTS

Thirty-two patients were included in the study group. Mean age at surgery was 14.7 years. Preoperative and postoperative concentrations of serum titanium and niobium were significantly different (P = 0.0001). Median postoperative serum concentrations of titanium and niobium were elevated 2.4- and 5.9-fold above the normal range respectively with 95% and 99% of samples elevated postoperatively. A significant and rapid rise in serum titanium and niobium levels was observed within the first postoperative week, after which elevated serum levels persisted up to 12 months.

CONCLUSION

We report abnormally elevated serum titanium and niobium levels in patients with titanium-based spinal instrumentation up to 12 months. The long-term systemic consequences of debris generated by wear and corrosion of spinal instrumentation is unclear but concerning, particularly as these implants inserted into the pediatric population may remain in situ for beyond 6 decades.

Ten-year outcome of serum metal ion levels after primary total hip arthroplasty: a concise follow-up of a previous report*

We previously reported on the metal ion concentrations of cobalt, chromium, and titanium that were found in the serum of patients three years after they had undergone primary total hip arthroplasty as compared with the concentrations found in the serum of control patients who did not have an implant. This study is a concise update on the serum metal levels found in a cohort of these patients ten years after the time of hip implantation. Of the original seventy-five subjects, metal ion levels were available for forty patients (53%). Ten patients (hybrid group) had received a hybrid total hip replacement that consisted of a modular cobalt-alloy femoral stem with a cobalt-alloy femoral head that had been inserted with cement and a titanium acetabular socket that had been inserted without cement. Nine patients (cobalt-chromium [CoCr] group) had received an implant with an extensively porous-coated modular cobalt-alloy femoral stem and femoral head along with a titanium acetabular socket; the femoral and acetabular components had each been inserted without cement. Eight patients (titanium group) had undergone insertion of a proximally porous-coated modular titanium-alloy femoral stem with a cobalt-alloy femoral head and a titanium acetabular socket; the femoral and acetabular components had each been inserted without cement. Thirteen patients (control group) from the original control group of patients who had not received an implant served as control subjects. Serum metal levels were measured with use of high-resolution sector field inductively coupled plasma mass spectrometry. The hybrid total hip arthroplasty group had mean cobalt levels that were 3.2 times higher at 120 months than they were at baseline, and the cobalt levels in that group were significantly higher than those in the titanium total hip arthroplasty group at thirty-six, sixty, eighty-four, ninety-six, and 120 months (p < 0.01). The hybrid group had mean chromium levels that were 3.9 times higher at 120 months than they were at baseline, and the CoCr total hip arthroplasty group had chromium levels that were 3.6 times higher at 120 months than they were at baseline. The serum titanium levels were higher in the titanium group at all follow-up time intervals as compared with the levels in all other groups, and the level in the titanium group at 120 months was eighteen times higher than it was at baseline (p < 0.01). Patients with well-functioning primary metal-on-polyethylene total hip replacements had elevated serum metal levels for as many as ten years postoperatively. Furthermore, metal release at the modular femoral head-neck junctions, rather than passive dissolution from porous ingrowth surfaces, was likely the dominant source of serum cobalt and chromium.

Metal ion effects on different types of cell line, metal ion incorporation into L929 and MC3T3-E1 cells, and activation of macrophage-like J774.1 cells

V ions showed high cytotoxicity for mouse fibroblast L929, osteoblastic MC3T3-E1, and macrophage-like J774.1 cells compared with Pb, Cu, Ni, Co, Zn, and Mo ions. The quantities of metal ions incorporated into the L929 and MC3T3-E1 cells increased with increasing metal concentration in the medium, depending on the metal ion type. In particular, the quantities of V incorporated into the cells were markedly higher than those of other metals. It was suggested that the cytotoxicity of a metal ion changes with the quantity of the metal ion incorporated into cells. It was also considered that V ions are incorporated into cells through xanthine derived from fetal bovine serum by high-performance liquid chromatography (HPLC). The strong interaction of Co, Ni and Mo with amino acids was analyzed by HPLC. The rate of increase of nitric oxide (NO) concentration released with the activation of the mouse macrophage-like J774.1 cells increased at a concentration of V ions ten times lower than that of Ni ions. The release of the cytokine tumor necrosis factor-α (TNF-α) from the J774.1 cells started at approximately 0.5 ppm V; interleukin-6 (IL-6) and transforming growth factor-β (TGF-β) showed a marked increase in the rate of increase at more than 1 ppm V. No increase in the concentration of IL-1α, IL-8, IL-15 or granulocyte macrophage-colony stimulating factor (GM-CSF) was observed for V and Ni ions.

Prospective study on serum metal levels in patients with metal-on-metal lumbar disc arthroplasty

PURPOSE

Metal-on-metal total disc replacement is a recent alternative treatment for degenerative disc disease. Wear and corrosion of these implants can lead to local and systemic transport of metal debris. This prospective longitudinal study examined the serum chromium and cobalt levels in 24 patients with cobalt-chromium alloy metal-on-metal lumbar disc replacements.

METHODS

Serum was assayed for chromium (Cr) and cobalt (Co) using high-resolution inductively-coupled plasma-mass spectrometry. Detection limits were 0.015 ng/mL for Cr and 0.04 ng/mL for Co.

RESULTS

Median serum Co levels at pre-op, 3, 6, 12, 24, and 36-months post-op were 0.10, 1.03, 0.96, 0.98, 0.67, and 0.52 ng/mL, respectively. Median serum Cr levels were 0.06, 0.49, 0.65, 0.43, 0.52, and 0.50 ng/mL, respectively.

CONCLUSION

In general, these results indicated that serum Co and Cr levels are elevated at all postoperative time points and are of the same order of magnitude as those observed in well-functioning metal-on-metal surface replacements of the hip and in metal-on-metal total hip replacements at similar postoperative time points.

An original method for the evaluation of in vivo controlled release of the ceramic materials

In recent years, the use of ceramic materials in orthopaedics and dentistry is becoming increasingly popular. However, it is important to know their biological and mechanical properties to optimize their use. The aim of this study is to describe a specific method to assess in vivo the effects of chronic release of ceramic materials implanted, in relation also to the type of material, pellets or powders. This was achieved by implanting ceramic powders and pellets, formed by low cohesion grains, in the patellar tendon of 48 New Zealand adult rabbits (24 with powders and 24 with pellets). The motion of the joint allowed easily and progressively the release of grains, detached from surface of the pellets and released to the joint space. Animals were sacrificed at different intervals (1, 3, 6, 12 months). Retrieved knee joints underwent X-Ray, histological and ultrastructural analysis.

Late recurrent hemarthrosis following knee arthroplasty associated with epithelioid angiosarcoma of bone

We report a case of recurrent hemarthrosis 1 year following total knee arthroplasty in a patient with no bleeding diathesis, the hemarthrosis was found to be related to, and led to the diagnosis of high grade sarcoma of the proximal tibia. Twenty five years earlier, he sustained a lateral tibial plateau fracture and was treated with open reduction and plating. Sarcoma developing in association with a metallic orthopedic prosthesis or hardware is an uncommon, but well-recognized complication. Sarcomas that occur adjacent to orthopaedic prostheses or hardware are of varied types, but are usually osteosarcoma or malignant fibrous histiocytoma.

In vitro biocompatibility evaluation of surface-modified titanium alloys

The present work is aimed to evaluate the effects of a surface modification process on the biocompatibility of three vanadium-free titanium alloys with biomedical applications interest. Chemical composition of alloys investigated, in weight %, were Ti-7Nb-6Al, Ti-13Nb-13Zr, and Ti-15Zr-4Nb. An easy and economic method intended to improve the biocompatibiblity of these materials consists in a simple thermal treatment at high temperature, 750 degrees C, in air for different times. The significance of modification of the surface properties to the biological response was studied putting in contact both untreated and thermally treated alloys with human cells in culture, Human Umbilical Vein Endothelial Cells (HUVEC) and Human Peripheral Blood Mononuclear Cells (PBMC). The TNF-alpha release data indicate that thermal treatment improves the biological response of the alloys. The notable enhancement of the surface roughness upon oxidation could be related with the observed reduction of the TNF-alpha levels for treated alloys. A different behavior of the two cell lines may be observed, when adhesion molecules (ICAM-1 and VCAM-1 in HUVEC, ICAM-1, and LFA-1 in PBMC) were determined, PBMC being more sensitive than HUVEC to the contact with the samples. The data also distinguish surface composition and corrosion resistance as significant parameters for the biological response.

In-vitro and in-vivo evaluation of a new Ti-15Mo-1Bi alloy

The newly developed Ti-15Mo-1Bi alloy not only possesses all the desirable mechanical properties inherent to beta-Ti Mo alloys, but may even enjoy better clinical applicability with the addition of bismuth element, which has long been administered as antibacterial and antitumor medicines. A significantly higher viability of 3T3 cells was demonstrated when they were grown on Ti-15Mo-1Bi alloy than on Ti-15Mo and Ti-6Al-4V. Cells incubated in the medium conditioned by Bi powder at 37 degrees C for 96 h exhibited viability similar to that in the blank group and higher than that in the Ni conditioned group. In vivo experiments using 6 mm x 2 mm metal pin implanted into the epicondyle of rabbit femur revealed superior potential of new bone growth and better persistence of the deposited bony tissue with the Ti-15Mo-1Bi alloy in contrast to that with Ti-6Al-4V. The difference is evident at 12th week and become even more prominent after 26 weeks, with the new bone area measuring 249% of that around Ti-6Al-4V alloy. In summary, Ti-15Mo-1Bi alloys show no cytotoxicity in the in-vitro test and demonstrates superior ability to retain bone in the in-vivo implantation experiment as compared with Ti-6Al-4V alloys.

In vivo acute toxicity of titanium dioxide nanoparticles to mice after intraperitioneal injection

Because of its excellent optical performance and electrical properties, TiO2 has a wide range of applications in many fields. It is often considered to be physiologically inert to humans. However, some recent studies have reported that nano-sized TiO2 may generate potential harm to the environment and humans. In this paper the in vivo acute toxicity of nano-sized TiO2 particles to adult mice was investigated. Mice were injected with different dosages of nano-sized TiO2 (0, 324, 648, 972, 1296, 1944 or 2592 mg kg(-1)). The effects of particles on serum biochemical levels were evaluated at various time points (24 h, 48 h, 7 days and 14 days). Tissues (spleen, heart, lung, kidney and liver) were collected for titanium content analysis and histopathological examination. Treated mice showed signs of acute toxicity such as passive behavior, loss of appetite, tremor and lethargy. Slightly elevated levels of the enzymes alanine aminotransferase and aspartate aminotransferase were found from the biochemical tests of serum whereas blood urea nitrogen was not significantly affected (P < 0.05). The accumulation of TiO2 was highest in spleen (P < 0.05). TiO2 was also deposited in liver, kidney and lung. Histopathological examinations showed that some TiO2 particles had entered the spleen and caused the lesion of spleen. Thrombosis was found in the pulmonary vascular system, which could be induced by the blocking of blood vessels with TiO2 particles. Moreover, hepatocellular necrosis and apoptosis, hepatic fibrosis, renal glomerulus swelling and interstitial pneumonia associated with alveolar septal thickening were also observed in high-dose groups.

Titanium allergy in dental implant patients: a clinical study on 1500 consecutive patients

BACKGROUND

In dentistry, allergic reactions to Ti implants have not been studied, nor considered by professionals. Placing permanent metal dental implants in allergic patients can provoke type IV or I reactions. Several symptoms have been described, from skin rashes and implant failure, to non-specific immune suppression.

OBJECTIVE

Our objective was to evaluate the presence of titanium allergy by the anamnesis and examination of patients, together with the selective use of cutaneous and epicutaneous testing, in patients treated with or intending to receive dental implants of such material.

MATERIAL AND METHODS

Thirty-five subjects out of 1500 implant patients treated and/or examined (2002-2004) were selected for Ti allergy analysis. Sixteen presented allergic symptoms after implant placement or unexplained implant failures [allergy compatible response group (ACRG)], while 19 had a history of other allergies, or were heavily Ti exposed during implant surgeries or had explained implant failures [predisposing factors group (PFG)]. Thirty-five controls were randomly selected (CG) in the Allergy Centre. Cutaneous and epicutaneous tests were carried out.

RESULTS

Nine out of the 1500 patients displayed positive (+) reactions to Ti allergy tests (0.6%): eight in the ACRG (50%), one in the PFG (5.3%)(P=0.009) and zero in the control group. Five positives were unexplained implant failures (five out of eight).

CONCLUSIONS

Ti allergy can be detected in dental implant patients, even though its estimated prevalence is low (0.6%). A significantly higher risk of positive allergic reaction was found in patients showing post-op allergy compatible response (ACRG), in which cases allergy tests could be recommended.

Levels of systemic metal ions in patients with intramedullary nails

BACKGROUND

It is being increasingly recognized that orthopedic implants are associated with adverse tissue responses, mediated by degradation products. Recent interest has been focused on the production of metal ions from hip arthroplasty. Few studies have reviewed fracture fixation devices and their metal ion production.

METHODS

61 subjects were enlisted into the study, with 3 subgroups. 21 subjects had Russell-Taylor intramedullary tibial nails in situ for 26 (21-32) months (316LVm stainless steel), 20 subjects had TriGen intramedullary tibial nails in situ for 43 (35-51) months (Ti-6Al-4V titanium alloy), and the remaining 20 subjects did not have any implant in situ and served as controls. Blood samples were taken and serum chromium, molybdenum, titanium, aluminium, and vanadium concentrations were measured using inductively coupled plasma (ICP) techniques.

RESULTS

The 3 groups were matched for age, sex, and BMI. The subjects with Russell-Taylor nails had elevated levels of chromium (0.10 microg/L) with median concentrations 2.5 times higher than those of the control group. The subjects with TriGen nails had less significantly elevated levels of titanium (6.5 microg/L).

INTERPRETATION

Stainless steel implants show significant differences from titanium implants in the dissemination of metal ions. Although the levels of chromium were elevated, the overall levels were modest when compared to published data regarding metal ion release and hip arthroplasty. Intramedullary nails are, however, often used in younger patients. If not removed, they may result in prolonged exposure to metal ions.

Biodistribution of titanium dioxide from biologic compartments

The layer of titanium dioxide (TiO(2)) of the implant is chronically exposed to the internal electrolyte milieu in the peri-implant biological compartment. Corrosion results from electrochemical attack and ensuing gradual degradation of the metallic materials and is thus of biological interest when these biomaterials are employed in clinical implantology. Herein we evaluated and compared the chronic effect and the biodistribution of TiO(2) administered subcutaneously or intraperitoneally. We propose that the compartmentalization of titanium in the area of subcutaneous injection would reproduce the biological compartment of the implant and its microenvironment from which metal ions could be released and migrate systemically. Potential TiO(2) deposits were identified and characterized in skin, liver and lung by histological and EDX analyses. After both treatments, the skin, liver, and lungs exhibited histological evidence of TiO(2) deposits. In order to characterize in situ macrophage-like cells, tissue sections were immunohistochemically stained for CD68. Tissue specimens from all organs assayed showed positive staining for anti-macrophage monoclonal antibody CD68 (PGM1). Despite the compartmentalization of titanium within nodular areas in rats treated subcutaneously, systemic migration occurred. We concluded that systemic migration of TiO(2) occurred regardless of the administration route.

Osteolysis and wear debris after total knee arthroplasty presenting with extra-articular metallosis in the calf

Component wear after total knee arthroplasty (TKA) with extruded metallosis in the extra-articular tissue of the calf secondary to a periprosthetic fracture is a rare complication. A 77-year-old man with a failed Insall-Burstein II TKA prosthesis presented with calf cellulitis after a fall. Radiologic evaluation revealed severe osteolysis and loosening of prosthetic components and an intramuscular abscess communicating with the medullary canal of the tibia through an undisplaced periprosthetic fracture. The patient developed rhabdomyolysis with acute renal failure. Drainage of the calf abscess showed staining of the muscles with wear debris and metallosis. The patient subsequently had debridement and excision of the infected TKA implant. Prompt diagnosis of this condition should be suspected in cases of failed arthroplasty with osteolysis and periprosthetic fracture.

Biological response of tissues with macrophagic activity to titanium dioxide

The titanium dioxide layer is composed mainly of anatase and rutile. This layer is prone to break, releasing particles to the milieu. Therefore, corrosion may cause implant failure and body contamination. We have previously shown that commercial anatase-titanium dioxide (TiO(2)-anatase) is deposited in organs with macrophagic activity, transported in the blood by phagocytic-mononuclear cells, and induces an increase in the production of reactive oxygen species (ROS). In this study, we evaluated the effects of rutile-titanium dioxide (TiO(2)-rutile). Male Wistar rats were injected i.p. with a suspension of TiO(2)-rutile powder at a dose of 1.60 g/100 g b.w. Six months postinjection, the presence of Ti was assessed in serum, blood cells, liver, spleen, and lung. Titanium was found in phagocytic mononuclear cells, serum, and in the parenchyma of all the organs tested. TiO(2)-rutile generated a rise in the percentage of reactive cells, which was smaller than that observed when TiO(2)-anatase was employed in a previous study. Although TiO(2)-rutile provoked an augmentation of ROS, it failed to induce damage to membrane lipids, possibly due to an adaptive response. The present study reveals that TiO(2)-rutile is less bioreactive than TiO(2)-anatase.

High-resolution ICP-MS determination of Ti, V, Cr, Co, Ni, and Mo in human blood and urine of patients implanted with a hip or knee prosthesis

The main components (Ti, V, Cr, Co, Ni, and Mo) of metallic alloys currently used in hip and knee articular prostheses have been simultaneously determined in human whole blood and urine of implanted people by a (HR)-ICP-MS method previously developed in our laboratory. The determination of those elements has been carried out in patients with knee and hip prosthesis and in a group of pre-operation patients without any metallic device in their bodies, used as controls, demonstrating the usefulness of this technique to perform multielement analysis at ppt levels in complex matrices. The concentrations of V, Cr, Co, Ni, and Mo in urine and blood of implanted people turned out to be very similar to those obtained in control patients. However, raised Ti levels could be found both in urine and blood of patients with articular prostheses made or coated with a titanium alloy (Ti(6)Al(4)V).

Serum titanium levels in individuals undergoing intramedullary femoral nailing with a titanium implant

BACKGROUND

Many patients request nail extraction or question the long-term effects of hardware retention. Systemic titanium degradation products may influence the timing of such decisions. The orthopedic literature provides no data regarding systemic titanium in patients undergoing intramedullary nail fixation with titanium implants. The purpose of this study was to determine the systemic level of serum titanium in patients who had undergone femoral nailing.

METHODS

Patients who underwent antegrade locked femoral nailing utilizing a reamed technique with a titanium implant were eligible to participate. Eight patients were recruited for each of four time points: 6 weeks, 3 months, 6 months, and 1 year. Blood samples were collected from each subject. Serum titanium levels were analyzed through inductively coupled plasma/mass spectrometry (ELAN DRC II, Perkin Elmer, SCIEX, Inc, Shelton, CT). Test sensitivity was 0.2 microg/L. Normal serum titanium levels are <150 microg/L.

RESULTS

Thirty-two patients were enrolled. The study group included 10 women and 22 men with average age of 32 (range 19-63) years. The most common fracture pattern was 32-A3 (n = 12), followed by 32-B2 (n = 9). No patients showed an elevated serum titanium level. Mean titanium levels were 49.38, 58.25, 49.38, and 50.63 microg/L at 6 weeks, 3 months, 6 months, and 12 months cohorts, respectively. No statistically significant differences were found (p = 0.207).

CONCLUSIONS

Standard intramedullary nail fixation of femur fractures did not result in elevated levels of serum titanium in the first year after surgery. Differences in serum titanium did not differ significantly across time since implantation.

Human macrophage response to UHMWPE, TiAlV, CoCr, and alumina particles: analysis of multiple cytokines using protein arrays

Aseptic loosening of total joint replacements is believed to be initiated by a macrophage response to prosthetic wear debris. To better characterize the early response to clinically relevant wear debris, we challenged primary human macrophages from four donors with ultra high molecular weight polyethylene (UHMWPE), TiAlV, CoCr, and alumina particles. After a 24-h culture, protein arrays were used to quantify the secretion of 30 different cytokines and chemokines. Macrophages secreted detectable levels of nine mediators in culture: Interleukin-1alpha (IL-1alpha), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, MCP-1, IL-8, IL-6, GM-CSF, IL-10, and IL-12p40. TiAlV particles were the most stimulatory, causing 5- to 900-fold higher cytokine expression compared with nonstimulated cells and uniquely eliciting high levels of IL-1alpha, IL-6, IL-10, and GM-CSF. CoCr and alumina were mildly stimulatory and typically elicited two- to fivefold greater levels than nonstimulated cells. Surprisingly, UHMWPE did not elicit a significant increase in cytokine release. Our data suggests that IL-1alpha, TNF-alpha, IL-1beta, and MCP-1 are the primary initiators of osteolysis and implicates metallic debris as an important trigger for their release.

Determination of metallic traces in kidneys, livers, lungs and spleens of rats with metallic implants after a long implantation time

Metallic transfer from implants does not stop at surrounding tissues, and metallic elements may be transferred by proteins to become lodged in organs far from the implant. This work presents an in vivo study of metallic implant corrosion to measure metallic element accumulation in organs located far from the implant, such as kidneys, livers, lungs and spleens. The studied metallic implant materials were CoCr alloy, Ti, and the experimental alloy MA956 coated with alpha-alumina. The implants were inserted in the hind legs of Wistar rats. Analysis for Co, Cr, Ti and Al metallic traces was performed after a long exposure time of 12 months by Inductively Coupled Plasma (ICP) with Mass Spectrometry (MS). According to the results, the highest Cr and Ti concentrations were detected in spleens. Co is mainly found in kidneys, since this element is eliminated via urine. Cr and Ti traces increased significantly in rat organs after the long implantation time. The organs of rats implanted with the alpha-alumina coated experimental MA956 did not present any variation in Al content after 12 months, which means there was no degradation of the alumina layer surface.

Malignant fibrous histiocytoma associated with coxofemoral arthrodesis

The discovery of biomaterials led to their use in the manufacture of implants for biomedical applications. In vivo, no metal or alloy is completely inert. The potential toxicity of some of the metals most frequently employed in the manufacture of orthopedic implants has been reported. Their carcinogenic potential has been evaluated in experimental animal models. However, few reports have discussed the potential development of malignant tumors associated with prosthetic structures in humans. The present study documents a case of intraosseous sarcoma that developed in the vicinity of a metallic prosthesis 43 months after a coxofemoral arthrodesis with metallic pins and screws. With this report the authors seek to contribute to the understanding of the potential toxicity and risks of using metallic implants. Since metallic implants employed in the rehabilitation of osteo-muscular-articular disorders usually remain in the organism for long periods of time, the need to monitor the metallic structures and the adjacent tissues is extremely relevant.

Metal ion levels in patients with stainless steel spinal instrumentation

STUDY DESIGN

Case-control study.

OBJECTIVES

To determine whether metal ion concentrations are elevated in patients with spinal instrumentation.

SUMMARY OF BACKGROUND DATA

Studies have shown that serum and urinary levels of component metal ions are abnormally elevated in patients with total joint arthroplasties. Little is known of metal ion release and concentrations in patients with spinal instrumentation.

METHODS

The study group consisted of patients who had undergone spinal instrumentation for various spinal disorders with a variety of stainless steel implants, 5 to 25 years previously. A group of volunteers without metal implants were controls. All subjects were tested for serum nickel, blood chromium, and random urine chromium/creatinine ratio estimation.

RESULTS

The study group consisted of 32 patients with retained implants and 12 patients whose implants had been removed. There were 26 unmatched controls. There was no difference in serum nickel and blood chromium levels between all 3 groups. The mean urinary chromium/creatinine ratio for patients with implants and those with implants removed was significantly greater than controls (P < 0.001). The difference between study subgroups was not significant (P = 0.16). Of several patient and instrumentation variables, only the number of couplings approached significance for correlation with the urine chromium excretion (P = 0.07).

CONCLUSION

Spinal implants do not raise the levels of serum nickel and blood chromium. There is evidence that metal ions are released from spinal implants and excreted in urine. The excretion of chromium in patients with spinal implants was significantly greater than normal controls although lower where the implants have been removed. The findings are consistent with low-grade release of ions from implants with rapid clearance, thus maintaining normal serum levels. Levels of metal ions in the body fluids probably do not reach a level that causes late side-effect; hence, routine removal of the implants cannot be recommended.

Analytical investigations of poly(acrylic acid) coatings electrodeposited on titanium-based implants: a versatile approach to biocompatibility enhancement

A polyacrylic acid film was synthesized on titanium substrates from aqueous solutions via an electroreductive process for the first time. This work was done in order to develop a versatile coating for titanium-based orthopaedic implants that acts as both an effective bioactive surface and an effective anti-corrosion barrier. The chemical structure of the PAA coating was investigated by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) was employed to evaluate the effect of annealing treatment on the morphology of the coatings in terms of their uniformity and porosity. Inductively coupled plasma mass spectrometry was used to measure ion concentrations in ion release tests performed on Ti-6Al-4V sheets modified with PAA coatings (annealed and unannealed). Results indicate that the annealing process produces coatings that possess considerable anti-corrosion performance. Moreover, the availability and the reactivity of the surface carboxylic groups were exploited in order to graft biological molecules onto the PAA-modified titanium implants. The feasibility of the grafting reaction was tested using a single aminoacid residue. A fluorinated aminoacid was selected, and the grafting reaction was monitored both by XPS, using fluorine as a marker element, and via quartz crystal microbalance (QCM) measurements. The success of the grafting reaction opens the door to the synthesis of a wide variety of PAA-based coatings that are functionalized with selected bioactive molecules and promote positive reactions with the biological system interfacing the implant while considerably reducing ion release into surrounding tissues.

Corrosion degradation and prevention by surface modification of biometallic materials

Metals, in addition to ceramics and polymers, are important class of materials considered for replacement of non-functional parts in the body. Stainless steel 316, titanium and titanium alloys, Co-Cr, and nitinol shape memory alloys are the most frequently used metallic materials. These alloys are prone to corrosion in various extents. This review briefly discusses the important biomaterials, their properties, and the physiological environment to which these materials are exposed. Corrosion performance of currently used metallic materials has been assessed and threat to the biocompatibility from corrosion products/metal ions is discussed. The possible preventive measures to improve corrosion resistance by surface modification and to increase the bioactivity of the metallic surfaces have also been discussed. Importance of the formation of oxide layers on the metal surface, another aspect of corrosion process, has been correlated with the host response. The gap areas and future direction of research are also outlined in the paper.

Bone formation at the surface of low modulus Ti-7.5Mo implants in rabbit femur

The biocompatibility of the Ti-7.5Mo alloy was examined, because the alloy has a high-strength/modulus ratio and thus is a potential candidate for orthopedic applications. Cell viability assay using 3T3 cells revealed that the Ti-7.5Mo did not induce apparent cell death, when the cells were grown on disks made of the alloy or incubated with the alloy-conditioned medium at 37 or 72 degrees C for 24-72h. The Ti-6Al-4V alloy was used as a control and did not cause apparent cell death either. Moreover, pins of 6mm long and 2mm in diameter of Ti-7.5Mo and Ti-6Al-4V were implanted into the left and right rabbit femurs, respectively, for 6, 12 and 26 weeks. New bone tissue grew to surround the pins, which spanned cortical and marrow regions, as shown by toluidine blue-stained bone sections of the three time points. Strikingly, the amount of new bone encircling the Ti-7.5Mo implant was approximate two-folds of that at Ti-6Al-4V by 26 weeks post-implantation. This facilitation of bone formation could be associated with the unique properties, such as a low modulus and the composition of Mo, of the Ti-7.5Mo.

Short-term microvascular response of striated muscle to cp-Ti, Ti-6Al-4V, and Ti-6Al-7Nb

Due to excellent mechanical properties and good corrosion resistance, titanium-aluminium-vanadium (Ti-6Al-4V) and titanium-aluminium-niobium (Ti-6Al-7Nb) are extensively used for orthopedic surgery. Concern has been voiced concerning the implications of the constituent vanadium in Ti-6Al-4V on the surrounding environment. Particularly in osteosynthesis where the alloys stand in direct contact to skeletal muscle, undesirable biologic reactions may have severe consequences. In a comparative study, we assessed in vivo nutritive perfusion and leukocytic response of striated muscle to the metals Ti-6Al-4V, Ti-6Al-7Nb, and commercially pure titanium (cpTi), thereby drawing conclusions on their short-term inflammatory potential. In 28 hamsters, utilizing the dorsal skinfold chamber preparation and intravital microscopy, we quantified primary and secondary leukocyte-endothelial cell interaction, leukocyte extravasation, microvascular diameter change, and capillary perfusion in collecting and postcapillary venules of skeletal muscle. A manifest discrepancy between the metals concerning impact on local microvascular parameters was not found. All metals induced an only transient and moderate inflammatory response. Only a slight increase in leukocyte recruitment and a more sluggish recuperation of inflammatory parameters in animals treated with Ti-6Al-4V compared to the other two metals suggested a minor, overall not significant discrepancy in biocompatibility. Gross toxicity of bulk Ti-6Al-4V on surrounding tissue could not be found. Conclusively, the commonly used biomaterials Ti-6Al-4V, Ti-6Al-7Nb, and cpTi induce an only transient inflammatory answer of the skeletal muscle microvascular system. Our results indicate that on the microvascular level the tested bulk Ti-alloys and cpTi do not cause adverse biologic reactions in striated muscle.