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Adsorption of collagenase to particulate titanium: a possible mechanism for collagenase localization in periprosthetic tissue.

Osteolysis is a central feature of aseptic loosening of orthopaedic joint prostheses. This destructive process is believed to result from phagocytosis of implant wear debris by periprosthetic and synovial macrophages and the subsequent release of proinflammatory mediators, including collagenase. Isolated murine macrophages were cultured in vitro with particulate titanium in order to explore the mechanism of macrophage activation by particulate wear debris. The results, in which the amount of secreted, soluble collagenase in culture supernatants was inversely proportional to titanium concentration, suggested that titanium strongly adsorbed secreted collagenase. This inference was confirmed by direct binding assays in which particulate titanium coated with adsorbed collagenase bound an alkaline phosphatase conjugated anti-collagenase antibody, but not a conjugated anti-IgG antibody. Adsorption of collagenase was not influenced by preincubation of titanium particles with albumin. The adsorbed collagenase remained enzymatically active as indicated by its ability to hydrolyze a synthetic peptide substrate. These results demonstrate that particulate titanium stimulates collagenase production by macrophages and then strongly adsorbs the secreted proinflammatory enzyme. The process of macrophage stimulation, collagenase secretion, and adsorption may represent an important mechanism for localization and concentration of collagenase in periprosthetic and synovial tissue, a mechanism that ultimately triggers bone resorption through osteoclast activation.

Adsorption↗

Surface modification by alkali and heat treatments in titanium alloys.

Pure titanium and titanium alloys are normally used for orthopedic and dental prostheses. Nevertheless, their chemical, biological, and mechanical properties still can be improved by the development of new preparation technologies. This has been the limiting factor for these metals to show low affinity to living bone. The purpose of this study is to improve the bone-bonding ability between titanium alloys and living bone through a chemically activated process and a thermally activated one. Two kinds of titanium alloys, a newly designed Ti-In-Nb-Ta alloy and a commercially available Ti-6Al-4V ELI alloy, were used in this study. In this study, surface modification of the titanium alloys by alkali and heat treatments (AHT), alkali treated in 5.0M NaOH solution, and heat treated in vacuum furnace at 600 degrees C, is reported. After AHT, the effects of the AHT on the bone integration property were evaluated in vitro. Surface morphologies of AHT were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Chemical compositional surface changes were investigated by X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS), and auger electron spectroscopy (AES). Titanium alloys with surface modification by AHT showed improved bioactive behavior, and the Ti-In-Nb-Ta alloy had better bioactivity than the Ti-6Al-4V ELI alloy in vitro.

Alkalies↗

Titanium-coated Dacron velour: a study of interfacial connective tissue formation.

Polyethylene terephthalate in textile form (Dacron) has been used extensively as a surgical implant material for applications such as vascular grafts and percutaneous access devices. It is moderately histocompatible eliciting a chronic inflammatory reaction predominately in tissue which has grown into the pores of the fabric. Titanium implants on the other hand, induce only the slightest inflammatory response and connective tissue adhesion to the titanium oxide surface is excellent. It was, therefore, hypothesized that a titanium coating on Dacron fabric might improve its histocompatibility while leaving its desirable mechanical properties unaffected. To test this idea, Dacron velour specimens were coated with titanium by vacuum deposition and were implanted together with uncoated controls in rabbits subcutis. After various implantation times, the specimens were recovered and the associated tissue was examined histologically. Qualitative and semiquantitative analysis revealed that tissue ingrowth quantity and quality was highly variable, not only between test and control specimens, but also between animals and even between specimens within the same animal. This indicated that there may be a number of factors influencing tissue ingrowth that were not adequately controlled in this study. The titanium coating which was undoubtedly highly oxidized had a profound qualitative and quantitative effect on fibroblast activity (ground substance formation) and fibroblast adhesion to the Dacron fibers. The results obtained after these short-term implantation periods indicate that titanium coating affects the quality of the interfacing tissue and may actually improve long-term histocompatibility. Long-term studies will have to confirm these preliminary data.

Animals↗

Effect of surface processing on the attachment, orientation, and proliferation of human gingival fibroblasts on titanium.

The adhesion, orientation, and proliferation of human gingival fibroblasts was studied on electropolished (elpTi), etched (etchTi), and sandblasted (sblTi) titanium surfaces. The texture, chemical state, and composition of the titanium surfaces were analyzed using a surface tracing instrument and electron spectroscopy for chemical analysis. Considerable differences were evident in the surface texture and chemical composition of the differently treated titanium plates. Electropolishing produced the smoothest and cleanest surface. Human gingival fibroblasts attached, spread, and proliferated on all titanium surfaces. However, cells on elpTi exhibited an extremely flat morphology and seemed to form cellular bridges with adjacent cells, whereas the etchTi and sblTi surfaces harbored both round and flat cells with many long processes. Cells on elpTi appeared to grow in thick layers with no specific orientation, whereas on etchTi surfaces they were migrating along the parallel, irregular minor grooves caused by mechanical polishing, and on sblTi surfaces they seemed to grow in clusters. Stress-fiber type actin bundles and vinculin-containing focal adhesions were present in cells spreading on elpTi and etchTi surfaces but not in cells spreading on sblTi surfaces. Cell shape, orientation, and proliferation appear to depend on the texture of the titanium surface and probably also on the properties of the oxide layer and adjacent bulk material. Our findings suggest that smooth or finely grooved titanium surfaces could be optimal in implants adjacent to soft tissues as they support the attachment and growth of human gingival fibroblasts.

Actin Cytoskeleton↗

Mechanical and histological investigation of hydrothermally treated and untreated anodic titanium oxide films containing Ca and P.

In a previous study a new method for forming thin hydroxyapatite (HA) layers on titanium was described. Titanium was anodized at 350 V in an electrolyte solution containing sodium beta-glycerophosphate and calcium acetate, and an anodic titanium oxide film containing Ca and P (AOFCP) was formed on the surface. Then numerous HA crystals were precipitated on the AOFCP during hydrothermal treatment in high-pressure steam at 300 degrees C. In this study three types of hydrothermally treated films differing in amounts of precipitated HA crystals and tensile adhesive strength, and untreated films were histologically and mechanically investigated in a transcortical rabbit femoral model for 8 weeks of implantation using light microscopy, scanning electron microscopy (SEM), and push-out tests. Machined titanium and HA ceramics served as control materials. The push-out shear strength and bone apposition of the AOFCP significantly increased after hydrothermal treatment, and were equivalent to those of HA ceramics, although the HA layer on the AOFCP was thin at 1-2 microns. From SEM observation of the pushed-out specimen, it was found that the thin HA layer had directly bonded to bone but the AOFCP had not. The push-out strength of the hydrothermally treated film resulted from the chemical bonding of the bone-HA layer interface, while that of the untreated film resulted from mechanical interlocking force between bone and the microprojections. There was a small difference in bone apposition but no significant difference in push-out strength with the amount of precipitated HA crystals on the treated films. Among the treated films, the film formed at the lowest electrolyte concentration showed the lowest bone apposition because of incomplete covering by the HA crystals, and showed the highest stability against mechanical failure because the adhesive strength was very high at about 38 mPa. Also, the hydrothermally untreated anodic oxide films, whose surfaces were rough as a result of the large microprojections, showed much higher push-out strength and bone apposition than titanium. The good hard-tissue compatibility may be attributed to the surface roughness and the possible inhibition of titanium ion release from the specimen.

Animals↗

Direct attachment of fibronectin to tresyl chloride-activated titanium.

The aim of this study was to bind fibronectin directly to a titanium surface treated with tresyl chloride (2,2,2-trifluoroethanesulfonyl chloride) for the development of a strong connection of a dental implant to subepithelial connective tissues and/or peri-implant epithelia. Basic terminal OH groups of mirror polished titanium were allowed to react with tresyl chloride at 37 degrees C for 2 days. The tresylated titanium disk was then immersed into a fibronectin/phosphate-buffered saline solution for 24 h at 37 degrees C. The activation reaction of the basic OH of titanium with tresyl chloride was confirmed by S2p, F1s, and O1s spectra using X-ray photoelectron spectroscopy and -O-S-O2- bonds using Fourier transform infrared reflection-absorption spectroscopy. After the reaction of fibronectin with titanium, the X-ray photoelectron spectroscopy revealed the remarkable effect of the activation of terminal OH groups with the tresyl chloride treatment. The N1s peak derived from the attached fibronectin still remained after 60 s of argon-ion sputtering after tresyl chloride treatment. In contrast, the N1s peak of the specimen not treated with tresyl chloride almost disappeared after only 10 s of argon-ion etching. Fibronectin, a well-known cell-adhesive protein, could easily be attached to the titanium surface by use of the tresyl chloride activation technique.

Coated Materials, Biocompatible↗

Increased osteoblast adhesion on titanium-coated hydroxylapatite that forms CaTiO3.

CaTiO(3) is a strong candidate to form at the interface between hydroxylapatite (HA) and titanium implants during many coating procedures. However, few studies have compared the cytocompatibility properties of CaTiO(3) to HA pertinent for bone-cell function. For this reason, the objective of the present in vitro study was to determine the ability of bone-forming cells (osteoblasts) to adhere on titanium coated with HA that resulted in the formation of CaTiO(3). To accomplish the formation of CaTiO(3), titanium was coated on HA discs and annealed either under air or a N(2)+H(2) environment. Materials were characterized by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). These characterization techniques demonstrated the formation of a nanometer rough CaTiO(3) layer as a consequence of interactions between HA and titanium during coating conditions. Results from cytocompatibility tests revealed increased osteoblast adhesion on materials that contained CaTiO(3) compared to both pure HA and uncoated titanium. The greatest osteoblast adhesion was observed on titanium-coated HA annealed under air conditions. Because adhesion is a crucial prerequisite to subsequent functions of osteoblasts (such as the deposition of calcium containing mineral), the present in vitro results imply that orthopedic coatings that form CaTiO(3) could increase osseointegration with juxtaposed bone needed for increased implant efficacy.

Animals↗

Surface analyses of micro-arc oxidized and hydrothermally treated titanium and effect on osteoblast behavior.

Osteoblast adhesion on the implant material surface is essential for the success of any implant in which osteointegration is required. Surface properties of implant material have a critical role in the cell adhesion progress. Titanium and its alloys are widespread and increasingly used as implant material in dentistry and orthopedics because of their excellent biocompatibility, which is attributed to a passive layer of TiO2 on the surface. In this study, the micro-arc oxidizing (MAO) and hydrothermally synthesizing (HS) methods were used to modify the TiO2 layer on the titanium surface. The surface microstructure was observed by scanning electron microscopy. The surface energy was assessed. The mouse osteoblastic cell line (MC3T3-E1) was seeded on the treated surfaces to evaluate their effect on cell behavior. This included cell adhesion kinetics, cell proliferation, cell morphology, and cytoskeletal organization. The surface structure of MAO samples exhibited micropores with a diameter of 1-3 microm, whereas the MAO-HS-treated samples showed additional multiple crystalline microparticles on the microporous surface. The surface energy of MAO and MAO-HS was higher than that of titanium. The cell adhesion rate was higher on the MAO-HS surface than on the MAO and titanium surface, but without any significant difference between them. After 3 days of culture, cells proliferated significantly more on the MAO and titanium surface than on the MAO-HS surface. The cytoskeletal organization was analyzed by actin and vinculin staining on all the samples. We conclude that the MAO and MAO-HS methods change the surface energy of TiO2 layer on the titanium surface. This may have an influence on the initial cell attachment. Other surface characteristics may be involved in the cell proliferation, which is different from cell attachment on the sample surface. A longer-duration cell experiment should be conducted to see the effect on cell differentiation. Future in vivo evaluation may give further evidence to optimize the surface character of this kind of implant material.

Actins↗

Titanium-cell interaction: analysis of gene expression profiling.

Titanium and its alloys are used worldwide in surgery. Dental implants, screws and plates, prostheses, and surgical instruments are made with titanium-based metals. The favorable characteristics that make this material desirable for implantation are (a) mechanical proprieties and (b) biocompatibility. The latter has been demonstrated by in vivo studies with animal models and clinical trials over a 40-year period. However, the exact effect of titanium on cells is still not well characterized. Expression profiling by DNA microarray is a new molecular technology that allows the analysis of gene expression in a cell system. Several genes whose expression was significantly up- or downregulated in an osteoblast-like cell line (MG-63) on titanium were identified with the use of DNA microarrays containing 19,200 genes. The differentially expressed genes are associated with a broad range of functional activities, including apoptosis, vesicular transport, and structural function. It was also possible to detect some genes whose function is unknown. The data reported are, to the author's knowledge, the first genetic portrait of titanium-cell interaction. They may help to provide a better understanding of the molecular mechanisms of titanium biocompatibility and serve as a model for studying the biocompatibility of other materials.

Animals↗

Enhanced fixation of implants by bone ingrowth to titanium fiber mesh: effect of incorporation of hydroxyapatite powder.

Tight fixation between bone and implant materials is of great importance for a successful outcome of procedures such as total knee arthroplasty (TKA) and total hip arthroplasty (THA). Titanium fiber mesh is an attractive structure for the establishment of tight fixation between bone and implant by bone ingrowth into the spaces among the fibers. Enhancement of bone ingrowth is desired not only for tight fixation but also for a fast recovery. Our hypothesis is that just the presence of hydroxyapatite (HA) particles ensures improved bone ingrowth, and that long-term stability can be obtained by mechanical anchoring of bone in the spaces among titanium fibers. In this study, we examine our hypothesis by in vivo experiment using dog femur. HA particles were incorporated in titanium fiber mesh coated on titanium alloy rod by dipping in a slurry of HA with hydroxy-propyl-cellulose in an ethanol solution. Specimens were implanted for 3, 5, and 8 weeks, and were then compared with the results from specimens without the use of HA. Bonding strength was evaluated by push-out test, and histomorphometric measurements were made with analysis software to calculate the average value of bone ingrowth. A significantly higher bonding strength was observed for the specimens with HA-incorporated implant at 3 and 5 weeks, and larger bone ingrowth deep inside the titanium fiber mesh was measured at 3 weeks. Our proposed method has the additional advantage of not requiring a high temperature that may result in changes in characters of HA powder such as phase transition, grain growth, and decomposition. Moreover, this technique of HA powder incorporation without high-temperature treatment allows the use of several types of metallic fiber mesh, as well as the application to fiber mesh made of organic polymers. We conclude that this simple modification of titanium fiber mesh with HA powder can improve the fixation of implant to bone in the initial stage after operation.

Animals↗

Effect of silver addition on the properties of nickel-titanium alloys for dental application.

Equiatomic and near-equiatomic nickel-titanium alloys exhibit a shape-memory effect and superelasticity. However, the properties of such alloys are extremely sensitive to the precise nickel-titanium ratio and the addition of alloying elements. High corrosion resistance is necessary for biomedical applications, especially orthodontic. The purpose of this study was to investigate the effect of silver addition to nickel-titanium alloys for dental and medical application. Arc melting, homogenization, hot rolling, and solution heat treatment were performed to prepare the nickel-titanium-silver (NiTi-Ag) specimens. The properties of the ternary NiTi-Ag alloys such as phase-transformation temperature, microstructure, microhardness, corrosion resistance, and cytotoxicity were investigated. The NiTi-Ag alloys showed low silver recovery rate for the cast alloy, due to silver's low evaporation temperature, and low silver solubility in nickel-titanium. Silver addition to nickel-titanium increased the transition temperature range to 100 degrees C and stabilized the martensitic phase (monoclinic structure) at room temperature, because the martensitic transformation starting temperature (Ms) was above room temperature. Martensitic and austenitic phases existed in X-ray diffraction patterns of solution-annealed NiTi-Ag alloys. The silver addition was considered to improve the corrosion resistance and form a stable passive film. Significantly, the mechanical properties of the silver-added alloys were dependent upon the amount of alloying addition. There was no toxicity in the NiTi-Ag alloys, as the response index showed none or mild levels.

Animals↗

Ciprofloxacin-releasing bioabsorbable polymer is superior to titanium in preventing Staphylococcus epidermidis attachment and biofilm formation in vitro.

Antibiotic coating systems have been successfully used to prevent bacterial attachment and biofilm formation. Our purpose was to evaluate whether bioabsorbable polylactide-co-glycolide (PLGA) 80/20 on its own, and PLGA together with ciprofloxacin (PLGA+C) have any advantages over titanium in preventing Staphylococcus epidermidis attachment and biofilm formation in vitro. Cylindrical specimens of titanium, PLGA, and PLGA+C in triplicate were examined for S. epidermidis ATCC 35989 attachment and biofilm formation after incubation with a bacterial suspension of about 10(5) cfu/mL for 1, 3, 7, 14, and 21 days, using scanning electron microscopy. Growth inhibition properties of PLGA and PLGA+C cylinders were tested on agar plates. On days 1, 3, and 21, no bacterial attachment was seen in 19.5, 9.2, and 41.4% of the titanium specimens; in 18.4, 28.7, and 34.5% of the PLGA specimens; and in 57.5, 62.1, and 57.5% of the PLGA+C specimens, respectively. During the whole study period, no biofilm was observed on 74-93% of the titanium specimens, 58-78% of the PLGA specimens, and 93-100% of the PLGA+C specimens. PLGA+C showed clear bacterial growth inhibition on agar plates, while PLGA and titanium did not show any inhibition. PLGA+C bioabsorbable material was superior to titanium in preventing bacterial attachment and biofilm formation and may have clinical applicability, for example, in prevention of infection in trauma surgery or in the treatment of chronic osteomyelitis.

Anti-Bacterial Agents↗

Particulate endocytosis mediates biological responses of human mesenchymal stem cells to titanium wear debris.

Continual loading and articulation cycles undergone by metallic (e.g., titanium) alloy arthroplasty prostheses lead to liberation of a large number of metallic debris particulates, which have long been implicated as a primary cause of periprosthetic osteolysis and postarthroplasty aseptic implant loosening. Long-term stability of total joint replacement prostheses relies on proper integration between implant biomaterial and osseous tissue, and factors that interfere with this integration are likely to cause osteolysis. Because multipotent mesenchymal stem cells (MSCs) located adjacent to the implant have an osteoprogenitor function and are critical contributors to osseous tissue integrity, when their functions or activities are compromised, osteolysis will most likely occur. To date, it is not certain or sufficiently confirmed whether MSCs endocytose titanium particles, and if so, whether particulate endocytosis has any effect on cellular responses to wear debris. This study seeks to clarify the phenomenon of titanium endocytosis by human MSCs (hMSCs), and investigates the influence of endocytosis on their activities. hMSCs incubated with commercially pure titanium particles exhibited internalized particles, as observed by scanning electron microscopy and confocal laser scanning microscopy, with time-dependent reduction in the number of extracellular particles. Particulate endocytosis was associated with reduced rates of cellular proliferation and cell-substrate adhesion, suppressed osteogenic differentiation, and increased rate of apoptosis. These cellular effects of exposure to titanium particles were reduced when endocytosis was inhibited by treatment with cytochalasin D, and no significant effect was seen when hMSCs were treated only with conditioned medium obtained from particulate-treated cells. These findings strongly suggest that the biological responses of hMSCs to wear debris are triggered primarily by the direct endocytosis of titanium particulates, and not mediated by secreted soluble factors. In this manner, therapeutical approaches that suppress particle endocytosis could reduce the bioreactivity of hMSCs to particulates, and enhance long-term orthopedic implant prognosis by minimizing wear-debris periprosthethic osteolysis.

Apoptosis↗

Virtues and drawbacks of titanium alloy aneurysm clips.

This report describes the imaging characteristics of titanium alloy aneurysm clips and our clinical experience with these clips in more than 300 patients. Phantom and clinical investigations showed that clip artifacts on CT and MR are minor as compared to the cobalt alloy clips used previously. Spiral CT angiography (CTA) in combination with titanium alloy clips could be shown to be a feasible mode of postoperative control and can be used to determine completeness of aneurysm elimination, patency of adjacent arteries as well as vasospasm. In contrast, magnetic resonance angiography (MRA) proved to be unfeasible as a method of postoperative vascular imaging since the titanium clips still produce a shadow in the order of size of the entire aneurysm. Therefore, completeness of aneurysm elimination cannot be judged on magnetic resonance angiography. The clinical experience in more than 300 cases showed that the titanium alloy clips essentially performed well. However, the limits of elastic deformation appear to be somewhat inferior to cobalt alloy clips. The standard appliers do not open the blades of the titanium clips quite as far as with the comparable cobalt alloy clips and the corresponding appliers. Therefore the titanium aneurysm clips are not quite as well suited for large broad based aneurysms. Furthermore, the increased susceptibility of the new clips with regard to abuse suggests to follow the recommendations of the manufacturer not to recycle and re-sterilize clips that have been tried but not permanently implanted.

Alloys↗

[Surface characterization of Al2O3-blasted titanium implants in total hip arthroplasty].

INTRODUCTION: Shot peening and grit blasting techniques are used in several surface modifications for producing hip endoprostheses. Corund blasting techniques using highly pure Al2O3 particles to create a rough surface of titanium implants in cementless total hip arthroplasty achieve better osteointegration. An increasing number of publications in maxillofacial surgery and orthopedic surgery show that there is a significant contamination on corund-blasted surfaces. The latest research studies reported an effect of contaminant particles on early failure of endoprostheses associated with third body wear. The aim of our work was to evaluate the amount and particle size of Al2O3 on the implant surface. MATERIAL AND METHOD: The surface of four different geometries (five parts each, ARR titanium acetabular reinforcement ring, anisotropic Vektor cup, Vektor titanium stem and modular MRP Titan stem) were analyzed with respect to Al2O3 particles. Grit blasting was performed with Al2O3 particles, Alodur SWSK, Fa. Treibacher. Field emission scanning electron microscopy (LEO 1525) was used for the detection of the Al2O3 particles at the implant surface with a backscattered electron detector. The particle size distribution as well as the average area of the covered surface was calculated with image analyzing software (analySIS, Soft Imaging System GmbH). RESULTS: The surface of the anisotropic Vektor cup was contaminated at an average of 41.7+/-4.9%, the Vektor titanium stem at an average of 33.3+/-4.7%, the (MRP) Titan stem at an average of 30.6+/-4.2%, and the ARR titanium acetabular reinforcement ring at an average of 23.2+/-1.6 with Al2O3 particles over the whole surface orientated to the bone. DISCUSSION: The results of this study clearly show that there is contamination of rough titanium surfaces with Al2O3 particles at an unexpectedly high percentage. With respect to third body wear in total hip arthroplasty, further studies are necessary to minimize contamination of roughened surfaces and maintain sufficient roughness for osteointegration.

Aluminum Oxide↗

Difference in metallic wear distribution released from commercially pure titanium compared with stainless steel plates.

INTRODUCTION: Stainless steel and commercially pure titanium are widely used materials in orthopedic implants. However, it is still being controversially discussed whether there are significant differences in tissue reaction and metallic release, which should result in a recommendation for preferred use in clinical practice. MATERIALS AND METHODS: A comparative study was performed using 14 stainless steel and 8 commercially pure titanium plates retrieved after a 12-month implantation period. To avoid contamination of the tissue with the elements under investigation, surgical instruments made of zirconium dioxide were used. The tissue samples were analyzed histologically and by inductively coupled plasma atomic emission spectrometry (ICP-AES) for accumulation of the metals Fe, Cr, Mo, Ni, and Ti in the local tissues. Implant corrosion was determined by the use of scanning electron microscopy (SEM). RESULTS: With grades 2 or higher in 9 implants, steel plates revealed a higher extent of corrosion in the SEM compared with titanium, where only one implant showed corrosion grade 2. Metal uptake of all measured ions (Fe, Cr, Mo, Ni) was significantly increased after stainless steel implantation, whereas titanium revealed only high concentrations for Ti. For the two implant materials, a different distribution of the accumulated metals was found by histological examination. Whereas specimens after steel implantation revealed a diffuse siderosis of connective tissue cells, those after titanium exhibited occasionally a focal siderosis due to implantation-associated bleeding. Neither titanium- nor stainless steel-loaded tissues revealed any signs of foreign-body reaction. CONCLUSION: We conclude from the increased release of toxic, allergic, and potentially carcinogenic ions adjacent to stainless steel that commercially pure Ti should be treated as the preferred material for osteosyntheses if a removal of the implant is not intended. However, neither material provoked a foreign-body reaction in the local tissues, thus cpTi cannot be recommend as the 'golden standard' for osteosynthesis material in general.

Adipose Tissue↗

Bioabsorbable vs. titanium screws in first metatarsophalangeal joint arthrodesis: a pilot randomized controlled trial with 2-year follow-up.

INTRODUCTION: To assess the feasibility and preliminary clinical outcomes of bioabsorbable screw fixation in first metatarsophalangeal joint arthrodesis compared to conventional titanium screw fixation. METHODS: In this prospective pilot randomized controlled trial, 30 patients were allocated 1:1 to bioabsorbable or titanium cannulated lag screw fixation. Arthrodesis was performed using a cup-and-cone technique at two Finnish hospitals. Full weight-bearing in an orthopaedic shoe was allowed after six weeks. Outcomes included AOFAS and VA-FAS FA-VAS scores, union rates, and complications assessed at 3, 6, 12, and 24 months. RESULTS: Both groups showed significant functional improvement with no between-group differences. At 24 months, mean AOFAS scores were 89.1 (SD 2.7) in the titanium group and 90.0 (SD 0.0) in the bioabsorbable group (p = 0.23). Mean FA-VAS total scores (sum of pain, function, and complaints subscales) were 1948 (SE 59.4) in the titanium group and 1914 (SE 61.4) in the bioabsorbable group (p = 0.655). Union rate was 90% overall; nonunion occurred in one titanium and two bioabsorbable patients, all requiring revision. No implant-related complications or hardware removal surgeries were recorded. Degradation of bioabsorbable screws caused no adverse clinical or radiographic reactions. CONCLUSIONS: Bioabsorbable screws appear safe and feasible in first metatarsophalangeal joint arthrodesis, with preliminary outcomes comparable to titanium fixation. These findings support the conduct of a larger confirmatory trial. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03133039, registered 28 April 2017. https://clinicaltrials.gov/ct2/show/NCT03133039.

Humans↗

Titanium coating of a polypropylene mesh for hernia repair: effect on biocompatibilty.

Titanium and its alloys are used worldwide in surgery. The favorable characteristics that make this material desirable for implantation are corrosion resistance and biocompatibility. Concerning hernia repair, a mesh modification has been developed using titanium layering of a polypropylene mesh implant, which is said to lead to an improved biocompatibility compared to commercially available mesh materials. To analyze the pure effect of titanium coating, two different mesh structures were studied using a standardized animal model. The titanium-coated monofilamentous, large porous, and lightweight mesh made of polypropylene and coated with titanium (PP+T) was compared to a pure polypropylene mesh manufactured with a similar structure and amount of material serving as a control (PP). In Sprague-Dawley rats, mesh samples were placed in a subcutaneuous position. Then 56, 84, and 182 days after mesh implantation, three animals from each group were sacrificed for morphological observations (amount of inflammatory and connective tissue formation, percentages of proliferating and apoptotic cells, percentage of macrophages). Both mesh modifications investigated showed an overall good biocompatibility. Macroscopic clinical observation after implantation of up to 182 days was uneventful. The tissue response to the PP as well as to the PP+T mesh was characterized by a moderate inflammatory tissue reaction limited to the perifilamentary region as is known for low weight, large porous, and monofilamentous mesh structures. No significant improvement of biocompatibility was found when analyzing the effect of titanium coating compared to the pure polypropylene mesh structure.

Animals↗