仿生电活性涂层钛植入材料促进骨结合的实验研究

目的评价仿生电活性钛酸钡(BaTiO3,BTO)/聚偏氟乙烯-三氟乙烯P(VDF-TrFE)涂层钛植入材料促进骨结合性能的效果。方法首先将直径为2 mm、长度为5 mm的医用纯钛圆柱进行表面喷砂-酸蚀处理,然后将BaTiO3/P(VDF-TrFE)溶液均匀涂覆在钛柱表面。待烘干后对涂层表面进行电晕极化处理。采用扫描电镜、能谱分析、原子力显微镜、水接触角测量仪分别对材料表面形貌、元素组成、表面粗糙度和亲疏水性进行表征检测,PLLA涂层钛柱作为对照材料。选取实验兔4只,在双侧胫骨位置各制备3个间隔为1 cm的圆形缺损,在左侧胫骨植入PLLA涂层钛柱,右侧胫骨植入仿生电活性涂层钛柱,术后4周和12周分别取材进行硬组织的骨形态检测分析。采用SPSS15.0软件对数据进行统计分析。结果理化性能表征检测显示,BaTiO3/P(VDF-TrFE)涂层和PLLA涂层均匀附着在钛柱表面,涂层厚度约50μm,且表面结构致密。电活性涂层可见钛酸钡纳米颗粒均匀分布在P(VDF-TrFE)基体内。两种涂层表面的粗糙度和水接触角无明显差异。电活性涂层具有稳定的压电性能,且压电常数接近生理量级。动物实验显示,术后4周,仿生电活性涂层材料表面和新骨结合紧密,涂层材料稳定无降解;而PLLA涂层材料表面由于材料有部分降解导致新骨结合较差,电活性涂层的骨结合率明显高于PLLA涂层。术后12周,两组的新骨成熟程度均增加,骨陷窝明显,仿生电活性涂层仍然保持稳定状态;而PLLA涂层进一步发生降解,和新骨结合程度弱于电活性涂层组。结论仿生电活性BaTiO3/P(VDF-TrFE)涂层钛可能作为一种具有促进骨整合功能的种植体涂层材料。     

Innovative antimicrobial coating of titanium implants with iodine

BackgroundPostoperative infection associated with implants remains a serious complication in orthopedic surgery. Several biomaterial surface treatments have been proposed as a means of reducing the incidence of implant-associated infections. In this study, a clinical trial was performed using an iodine-supported titanium that suppresses the microbial activities.MethodsA total of 222 patients with postoperative infection or compromised status were treated using iodine-supported titanium implants. The mean age of the patients was 49.4 years (range 5–85 years). One hundred twenty-seven patients were male and 95 were female. In 158 patients, iodine-supported implants were used to prevent infection, such as compromised hosts and conditions, and in 64 patients to treat active infection. White blood cell (WBCs) and C-reactive protein (CRP) levels were measured pre- and postoperatively in all patients. To confirm whether iodine from the implant affected physiological functions, thyroid hormone levels in the blood were examined. Both examinations were conducted sequentially for a year. Radiological evaluations were performed regularly after the operation. The chronological changes of the iodine amount were evaluated using half pins removed after completion of external fixation.ResultsThe mean follow-up period was 18.4 months (range 3–44 months). Acute infection developed in three tumor cases among the 158 patients on preventive therapy. All three recovered without removal of the implants. Infection was cured in all 64 patients with infection. Median WBC levels were in the normal range, and median CRP levels returned to <0.5 within 4 weeks after surgery. Abnormalities of thyroid gland function were not detected. None of the patients experienced loosening of the implants. There were two patients with mechanical implant failure, which was treated by re-implantation. Excellent bone ingrowth and ongrowth were found around all hip and tumor prostheses. One year later, the amount of iodine on external fixation pins remained about 20–30 %.ConclusionsIodine-supported titanium implants can be very effective for preventing and treating infections after orthopedic surgery. Cytotoxicity and adverse effects were not detected.     

Prophylaxis of infection and effects on osseointegration using a tobramycin-periapatite coating on titanium implants—An experimental study in the rabbit

No options are available for local antibiotic delivery from uncemented implants. By loading a porous titanium implant with a biomimetic HA-coating (PeriApatite, PA) with antibiotics, we could obtain adequate local antibiotic concentrations and reduce infection susceptibility. This study investigated the efficacy of a tobramycin-loaded PA-coated titanium foam implant in preventing infection, as well as the effects on osseointegration. In 72 New Zealand White rabbits, an uncoated (Ti), PA-coated (PA), or Tobramycin-PA-coated (PA-tobra) titanium foam rod was implanted intramedullary in the left tibiae after contamination of the implant bed with none (control), 10³, 10⁴ or 10⁵ CFU Staphylococcus aureus. PA-tobra implants were loaded with 2.4 mg tobramycin. After 28 days analysis was done by bacteriology, histopathology and histomorphometry. Six percent of the contaminated PA-tobra rabbits were infected, whereas this was 53 and 67% for PA and Ti, respectively (p < 0.001). Quantitative cultures were also significantly lower in the PA-tobra group (p = 0.003). None of the control rabbits were infected. Histopathological and histomorphometrical scores were both better for the PA-tobra group, although only significant compared to Ti. No significant differences were observed between PA and Ti rabbits. We conclude that the application of tobramycin to PA-coated titanium foam implants appears to be an effective local antibiotic strategy for uncemented implants for infection prophylaxis and has a beneficial effect on implant fixation, which will result in improved long-term implant survival. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 710–716, 2009     

骨折内固定表面抗生素涂层的体外观察研究

目的 研究内固定表面聚消旋乳酸(PDLLA)结合庆大霉素涂层的体外特性,包括涂层的定量、机械稳定性、无菌性和药物释放特性.方法 应用电子半微量天平和扫描电镜测定涂层的质量与厚度.通过髓腔内的插拔试验确定涂层的机械稳定性.用细菌培养的方法确定涂层过程是否无菌.最后将涂层克氏针浸泡在磷酸盐缓冲溶液中,应用称重法测定涂层在不同时间段的重量损失及用ELISA法测定溶液中释放出的抗生素浓度.结果 涂层的平均重量为(7.2±0.9)mg,涂层的厚度为(13.5±1.7)μm.插拔试验测定涂层的重量损失为(3.5±1.3)%,扫描电镜证明插拔试验后,内固定表面的涂层都是完整、规则的.所有样本在经过血培养及胰蛋白酶培养后均未发现细菌生长.在6周时涂层的重量减少约6.4%.在最初的4 h内庆大霉素呈爆发性释放,之后缓慢而稳定地释放,并且释放可以至少持续6周.结论 内固定表面的PDLLA结合庆大霉素的抗生素涂层具备手术操作所需要的机械稳定性和无菌性.     

Improved osseointegration of titanium implants after surface coating with polymers in a rabbit model

In this study we present the first results of the investigation of polymer-coated titanium implants implanted in the proximal tibia and distal femora of New Zealand white rabbits. The results of DEXA scans, micro-CT, and histological analysis showed an increase of osseointegration. We suggest that controlled release kinetics after coupling of these polymers with BMP-2 can additionally increase osseointegration.     

The effect of hydroxyapatite coating on bone growth into porous titanium alloy implants

In rabbits and goats, test implants with a porous surface of two layers of Tl-6A;-4V beads were examined at intervals for bond strength with bone. Half of the implants were coated with hydroxyapatite by plasma spray. The bonding strength with bone in the coated specimens was about four times greater than that of the uncoated specimens at two weeks, and twice as strong at six weeks. Twelve weeks after implantation, the strengths were similar. The hydroxyapatite coating of the beads provided earlier and stronger fixation.     

Effect on infection resistance of a local antiseptic and antibiotic coating on osteosynthesis implants: an in vitro and in vivo study.

The purpose of this study was to acquire information about the effect of an antibacterial and biodegradable poly-L-lactide (PLLA) coated titanium plate osteosynthesis on local infection resistance. For our in vitro and in vivo experiments, we used six-hole AO DC minifragment titanium plates. The implants were coated with biodegradable, semiamorphous PLLA (coating about 30 microm thick). This acted as a carrier substance to which either antibiotics or antiseptics were added. The antibiotic we applied was a combination of Rifampicin and fusidic acid; the antiseptic was a combination of Octenidin and Irgasan. This produced the following groups: Group I: six-hole AO DC minifragment titanium plate without PLLA; Group II: six-hole AO DC minifragment titanium plate with PLLA without antibiotics/antiseptics; Group III: six-hole AO DC minifragment titanium plate with PLLA + 3% Rifampicin and 7% fusidic acid; Group IV: six-hole AO DC minifragment titanium plate with PLLA + 2% Octenidin and 8% Irgasan. In vitro, we investigated the degradation and the release of the PLLA coating over a period of 6 weeks, the bactericidal efficacy of antibiotics/antiseptics after their release from the coating and the bacterial adhesion of Staphylococcus aureus to the implants. In vivo, we compared the infection rates in white New Zealand rabbits after titanium plate osteosynthesis of the tibia with or without antibacterial coating after local percutaneous bacterial inoculations at different concentrations (2 x 10(5)-2 x 10(8)): The plate, the contaminated soft tissues and the underlying bone were removed under sterile conditions after 28 days and quantitatively evaluated for bacterial growth. A stepwise experimental design with an "up-and-down" dosage technique was used to adjust the bacterial challenge in the area of the ID50 (50% infection dose). Statistical evaluation of the differences between the infection rates of both groups was performed using the two-sided Fisher exact test (p < 0.05). Over a period of 6 weeks, a continuous degradation of the PLLA coating of 13%, on average, was seen in vitro in 0.9% NaCl solution. The elution tests on titanium implants with antibiotic or antiseptic coatings produced average release values of 60% of the incorporated antibiotic or 62% of the incorporated antiseptic within the first 60 min. This was followed by a much slower, but nevertheless continuous, release of the incorporated antibiotic and antiseptic over days and weeks. At the end of the test period of 42 days, 20% of the incorporated antibiotic and 15% of the incorporated antiseptic had not yet been released from the coating. The antibacterial effect of the antibiotic/antiseptic is not lost by integrating it into the PLLA coating. The overall infection rate in the in vivo investigation was 50%. For Groups I and II the infection rate was both 83% (10 of 12 animals). In Groups III and IV with antibacterial coating, the infection rate was both 17% (2 of 12 animals). The ID50 in the antibacterial coated Groups III and IV was recorded as 1 x 10(8) CFU, whereas the ID50 values in the Groups I and II without antibacterial coating were a hundred times lower at 1 x 10(6) CFU, respectively. The difference between the groups with and without antibacterial coating was statistically significant (p = 0.033). Using an antibacterial biodegradable PLLA coating on titanium plates, a significant reduction of infection rate in an in vitro and in vivo investigation could be demonstrated. For the first time, to our knowledge, we were able to show, under standardized and reproducible conditions, that an antiseptic coating leads to the same reduction in infection rate as an antibiotic coating. Taking the problem of antibiotic-induced bacterial resistance into consideration, we thus regard the antiseptic coating, which shows the same level of effectiveness, as advantageous.     

Effects of hydroxyapatite tricalcium phosphate coating and intracancellous placement on bone ingrowth in titanium fibermetal implants

The purpose of this study was to compare the host—bone response to hydroxyapatite/tricalcium phosphate (HA/TCP)-coated and noncoated titanium fibermetal implants placed in a load-sharing cancellous bone environment of the distal femurs of rabbits. The influence of implantation site was also investigated by comparing these intracancellous implants with intramedullary implants evaluated in a previous study. Three parameters were measured: percentage implant perimeter surface length in contact with new bone, percentage internal fibermetal surface length in contact with ingrown bone, and percentage of available pore space filled with bone. The HA/TCP coating significantly accelerated and increased bone ongrowth, new bone formation on the perimeter and internal surface of the implants. This effect was evident as early as 2 weeks after implantation. In contrast, there was no difference between HA/TCP-coated and noncoated implants in the bone ingrowth parameter, percentage of available pore space filled with bone, or pull-out strength. Scanning electron microscopy in the backscatter mode demonstrated that new bone formed directly onto the HA/TCP-coated fibers and did not usually form directly on noncoated fibers. Analysis of fluorochrome labeling revealed that bone formation in weeks 1 through 4 was primarily woven and there-after lamellar. Compared with intramedullary placement, intracancellous placement significantly accelerated the apposition of bone to the perimeter and internal surface of HA/TCP-coated implants and both accelerated and increased bone ingrowth as a percentage of available pore volume. These data show that the host response to titanium fibermetal implants is influenced both by HA/TCP coating and by the implantation site.     

Bioactive glass enhances bone ingrowth into the porous titanium coating on orthopaedic implants

Purpose

The aim of the study was to verify the ability of nanoparticulate bioactive glass (BAG) to infiltrate into the porous titanium (Ti) layer on Ti-based implants to promote osseointegration.

Methods

The porous titanium layer on Ti-based implants was impregnated with nanoparticulate BAG. The implants without or with BAG were implanted bilaterally in tibial holes of ten New Zealand white rabbits. The rabbits were sacrificed after ten weeks for examinations. Beside histological examination, EDXS analysis of polished cross-sections of explanted implants was also performed with the aim to quantitatively evaluate the bone-to-pore contact and bone-in-pore ratio.

Results

After ten weeks, EDXS analyses of cross-sections of the explanted implants confirmed that bioactive glass was fully resorbed and that the pores throughout the thickness of the porous titanium layer were to a large extent filled with a new bone. In the absence of bioactive glass, only the outer part of the porous layer was filled with bone. The implants without BAG in the porous Ti-layer exhibited similar bone-to-pore contact, while significant improvement of bone ingrowth into the pores was observed for the implants with BAG (38%), as opposed to those without it (22%).

Conclusion

This study confirmed that the nanoparticulate bioactive glass within the porous titanium surface layer on implants promotes osseointegration and stimulates the formation of bone within the pores.     

The effect of different cleaning methods on the surface and temperature of failed titanium implants: an in vitro study

The aims of this in vitro study are to compare the efficacy of different cleaning methods in removing debris of failed implants and to detect thermal changes of the implants treated by various scaling instruments. Twenty-seven failed implants and two unused implants as control were included to this study—group 1: plastic curette (P), group 2: titanium curette (T), group 3: carbon curette (C), group 4: titanium brush (TB), group 5: Er:YAG laser (laser 1 (L1) 100 mJ/pulse at 10 Hz), group 6: Er:YAG laser (laser 2 (L2) 150 mJ/pulse at 10 Hz), group 7: Er:YAG laser (laser 3 (L3) 200 mJ/pulse at 10 Hz), group 8: ultrasonic scaler appropriate for titanium (US), group 9: air abrasive method (AA)?+?citric acid, and group 10: implantoplasty (I). The changes on the treated/untreated titanium surfaces and remnant debris were observed by scanning electron microscopy (SEM). Temperature of the implants before and after treatment was detected using a thermocouple. The use of air abrasive and citric acid combination and Er:YAG laser groups was found as the best methods for the decontamination of titanium surfaces of failed implant. When the hand instruments were compared, titanium curette was found better than both the plastic and the carbon curettes which leave plastics and carbon remnants on the titanium surface. The temperature was higher after hand instrumentation when compared to other experimental groups (p?<?0.05). Within the limitations of the present in vitro model, it can be concluded that the best method for decontamination of the implant surface is the use of air abrasives and Er:YAG laser.     

Osseointegration of porous titanium implants with and without electrochemically deposited DCPD coating in an ovine model

Background

Alendronate (ALN) is the most common form of bisphosphonates used for the treatment of osteoporosis. Osteoprotegerin (OPG) has also been shown to reduce osteoporotic changes in both humans and experimental animals after systemic administration. The aim of this current study was to test if the anti-resorption effects of ALN may be enhanced when used in combination with OPG.

Objectives

To investigate the effects of ALN, OPG or combined on bone mass and bone mechanical properties in ovariectomized (OVX) rats.

Methods

OVX rats were treated with ALN, OPG-Fc, or OPG-Fc and ALN. Biochemical markers, trabecular bone mass, biomechanics, histomorphometry and RANKL expression in the bone tissues were examined following the treatments.

Results

The treatment of ALN, OPG-Fc and ALN+OPG-Fc all prevented bone loss in the OVX-rats, there was no statistical difference among the three treatment groups in terms of vertebrae BMD, mineralizing surfaces, mineral apposition rate, BFR/BS. The ALN+OPG-Fc treatment group had significantly increased the mechanical strength of lumber vertebral bodies and femoral shafts when compared to the ALN and OPG-Fc treatment groups. The RANKL protein expression in the vertebral bones was significantly decreased in the ALN and ALN+OPG-Fc treatment groups, suggesting the combined use of OPG-Fc and ALN might have amplified inhibition of bone resorption through inhibiting RANKL-dependent osteoclastogenesis.

Conclusion

The combined use of OPG-Fc and ALN may be a new treatment strategy for reversing bone loss and restoring bone quality in osteoprotic disorders.     

Bone morphogenetic protein-2 coating of titanium implants increases biomechanical strength and accelerates bone remodeling in fracture treatment: a biomechanical and histological study in rats

Bone morphogenetic protein-2 (BMP-2), a member of the transforming growth factor (TGF)-beta superfamily, is known to be a very potent osteoinductive growth factor. The purpose of this study was to investigate the effect of BMP-2 (5% [w/w], 50 microg on each nail), locally released from poly(D,L-lactide) (PDLLA)-coated intramedullary implants, on fracture healing. A closed fracture of the right tibia of 5-month-old Sprague-Dawley rats (n = 64) was intramedullary stabilized with uncoated vs. BMP-2-coated titanium Kirschner wires. X-ray examinations (posteroanterior and lateral) were performed throughout the experiment. At 28 and 42 days after fracture, the animals were killed and both tibiae were dissected for biomechanical torsional testing. For histological and histomorphometric evaluation, 5 microm sections were obtained, stained with Safranin-O/light green and von Kossa, and examined using an image analysis system. The radiological results demonstrated progressed callus consolidation in the BMP-2-treated groups compared with the uncoated groups at both timepoints. Histomorphometric evaluation showed progressed callus remodeling with significantly increased mineralization and less cartilage of the periosteal callus. Due to the BMP-2 treatment, increased mineralization of the cortices was detected at 28 and 42 days after fracture. Biomechanical testing revealed significantly elevated maximum load and torsional stiffness in the BMP-2-treated groups compared with controls at both timepoints. The results clearly demonstrate that local application of BMP-2 from PDLLA-coated implants is feasible and significantly accelerates fracture healing. Local administration of growth factors from coated implants could reduce clinical problems in fracture treatment without opening of the fracture, implantation of further devices, or injection with the risk of infection or side effects caused by other carriers.     

Osseointegration study of porous nitinol versus titanium orthopaedic implants

The functionality of a new metallic interbody fusion implant manufactured out of porous nitinol (PNT) was evaluated in sheep and compared to a conventional titanium (TiAIV) intervertebral cage packed with autologous iliac crest bone. Both device types were implanted at two non-contiguous intervertebral lumbar sites. The objective was to evaluate the osseointegration capacity after 3, 6 and 12 months of implantation in the presence of these two implant types subjected to the same mechanical loads. Two-dimensional radiology, computer tomography and histology were used as techniques of parameter evaluation. The results indicated that PNT obtained a better intervertebral osseointegration capacity compared to the TiAlV cage. The functional difficulties of the titanium implant were related to its instability at the implantation site possibly due to a biofunctionality problem. The biocompatibility of both implants seemed comparable, however.     

Experience with percutaneous titanium implants in the head and neck: a clinical and histological study

Percutaneous implants have been associated with numerous problems. However, by using skin-penetrating, bone-anchored titanium implants, developed by Professor Br?nemark at the Department of Anatomy, University of G?teborg, good long-term results have been observed. These implants have been in clinical use for anchorage of bone-conducting hearing aids and facial prostheses since 1977 and 1979, respectively. The total number of implants is approximately 700. Less than 4% of the observations have shown significant irritation. Biopsies from 33 patients were collected for histological studies. In the irritated skin there was an increased number of inflammatory cells, mainly polymorphonuclear cells, B-cells, and plasma cells but not T-cells. This suggests a response directed against exogenous agents rather than an allergic reaction against the implant per se.     

In vitro study of shear force on interbody implants

OBJECTIVE: The lordosis of the lumbar spine and body weight result in significant shear forces through the lumbosacral disc spaces. These forces result in translational motion across the disc space, which is resisted but not completely abolished by pedicle screw stabilization. It is postulated that this motion may be a factor in the development of nonunion of lumbar interbody fusions. An in vitro study of the micromotion of porcine specimens implanted with serrated or smooth interbody spacers and subjected to shear forces under compressive preload was conducted to determine whether the surface serrations on vertebral interbody implants significantly resist shear forces and resulting sagittal translation. METHODS: Measurements of anterior vertebral translation were recorded on porcine cervical spine segments, subjected to 25 N of anteroposterior shear load while under a 300-N compressive preload. Baseline testing was performed on intact specimens and partially destabilized specimens (facet joints removed). Following partial discectomy, the specimens were divided into two groups for testing: one using smooth-surfaced and one using serrated interbody spacers. RESULTS: Under 25-N shear load, the specimens tested with the serrated spacers showed anterior vertebral translation of 0.046 +/- 0.013 mm, whereas those tested with the smooth spacers measured 0.152 +/- 0.075 mm (P < 0.01). CONCLUSIONS: The presence of surface serrations on the interbody implants significantly increased the resistance to shear forces in this model. In the clinical setting, we postulate that micromotion at interbody fusion sites will be substantially less when serrated implants are used and may help reduce the incidence of nonunion.     

Early bone growth on the surface of titanium implants in rat femur is enhanced by an amorphous diamond coating

Background and purpose

Amorphous diamond (AD) is a durable and compatible biomaterial for joint prostheses. Knowledge regarding bone growth on AD-coated implants and their early-stage osseointegration is poor. We investigated bone growth on AD-coated cementless intramedullary implants implanted in rats. Titanium was chosen as a reference due to its well-known performance.

Materials and methods

We placed AD-coated and non-coated titanium implants (R_a ≈ 0.2 μm) into the femoral bone marrow of 25 rats. The animals were divided in 2 groups according to implant coating and they were killed after 4 or 12 weeks. The osseointegration of the implants was examined from hard tissue specimens by measuring the new bone formation on their surface.

Results

4 weeks after the operation, the thickness of new bone in the AD-coated group was greater than that in the non-coated group (15.3 (SD 7.1) μm vs. 7.6 (SD 6.0) μm). 12 weeks after the operation, the thickness of new bone was similar in the non-coated group and in the AD-coated group.

Interpretation

We conclude that AD coating of femoral implants can enhance bone ongrowth in rats in the acute, early stage after the operation and might be an improvement over earlier coatings.One of the important factors preventing loosening of joint prosthesis is early fixation, i.e. firm attachment of the prosthesis to the bone. The mechanical properties of modern bone cements correspond well with those of bone, and the survival of cemented implants is good (Aamodt et al. 2004). However, cementless prostheses have been suggested to have minimal stress shielding (Ellison et al. 2009) and even superior survival rate (Moreland and Moreno 2001, Emerson et al. 2002, Sorrells et al. 2004, Hooper et al. 2009, Yamada et al. 2009).Because bone attachment is much more durable and stable than fibrous attachment, the best type of prosthesis attachment is achieved with new bone contact and not by scarring. The formation of new bone is most active in the early postoperative stage. On the other hand, the bone loss is at its highest level in the acute stage. After this stage, the velocity of bone loss equals that of normal age-induced osteoporosis (Venesmaa et al. 2000, 2001, 2003). One way to influence periprosthetic bone loss and related bone density changes is use of better coatings for early-stage osseointegration (Schopper et al. 2005). Hydroxyapatite coating has a bone growth-inducing effect (Santori et al. 2001). Fluorapatite, which releases less ions to the surrounding tissue than hydroxyapatite, also enhances osseointegration (Bhadang and Gross 2004). In a study by Guglielmotti et al. (1999), implants coated with diamond-like carbon (DLC) were placed in the tibias of Wistar rats and were found to osseointegrate better than non-coated titanium implants.Amorphous diamond (AD), one of the DLC coatings, is a durable, versatile and highly bio-compatible biomaterial that is scratch-resistant and forms a strong attachment to bone cement (Santavirta et al. 1999, Toyras et al. 2005, Lappalainen and Selenius 2008). However, our knowledge regarding bone growth on the surface of AD at different follow-up times is still poor. We examined bone growth on AD-coated femoral implants in rats 4 and 12 weeks postoperatively. We hypothesized that AD enhances osseointegration in both of the observation points mentioned above. The reason for the study was investigation of possible clinical applications as a prosthesis coating for cementless fixation.     

Histological,mechanical, and radiological study of osteoformation in titanium foam implants

Background

Titanium (Ti) is widely used for implants because of its high mechanical reliability and because it aids osteoformation. However, it also produces artifacts during radiological imaging. Further, Ti implants can sometimes cause the surrounding bone to break. Owing to recent advances, Ti can be transformed into sponge-like, porous materials having a three-dimensional network of pores; such materials are called Ti foams. These foams exhibit distinct characteristics that make them more suitable than nonporous Ti. The objective of this study was to evaluate Ti foams as implant materials.

Methods

Implants based on Ti foams having porosities of 80 % and 90 % were embedded in the femurs of 11 rabbits. Implants based on 0 % porosity Ti were used as controls. Five rabbits were sacrificed 4 weeks after implantation, while the remaining were sacrificed after 12 weeks. The femurs containing the Ti implants were harvested and analyzed.

Results

Biomechanical analyses showed that the 80 % porosity implants induced greater osteoformation. There were significant differences in the average pushout strengths of the control and 80 % porosity implants after 4 weeks (p?=?0.048) and 12 weeks (p?=?0.001). Histopathological analyses confirmed osteoformation in the case of the 80 % porosity implants. Analyses of the micro-computed tomography images of the Ti foam-based implants did not suggest the presence of artifacts.

Conclusions

The 80 % porosity Ti implants did not exhibit the shortcomings associated with conventional Ti implants. In addition, they induced greater osteoformation. Finally, the Ti foams did not produce radiological artifacts.