Corrosion behavior of tantalum-coated cobalt-chromium modular necks compared to titanium modular necks in a simulator test

This study compared the corrosion behavior of tantalum-coated cobalt-chromium modular necks with that of titanium alloy modular necks at their junction to titanium-alloy femoral stem. Tests were performed in a dry assembly and two wet assemblies, one contaminated with calf serum and the other contaminated with calf serum and bone particles. Whereas the titanium modular neck tested in the dry assembly showed no signs of corrosion, the titanium modular necks tested in both wet assemblies showed marked depositions and corrosive attacks. By contrast, the tantalum-coated cobalt-chromium modular necks showed no traces of corrosion or chemical attack in any of the three assemblies. This study confirms the protective effect of tantalum coating the taper region of cobalt-chromium modular neck components, suggesting that the use of tantalum may reduce the risk of implant failure due to corrosion.

Proximal humeral nonunion treated with an intramedullary tantalum cylinder

Nonunion is uncommon after proximal humerus fracture surgery. There is no agreement about preferred method of treatment. Traditional approaches have included laterally based locking plates, autogenous grafting, and endosteal support to provide improved biomechanical stability. Open reduction and internal fixation (ORIF) of proximal humeral nonunion has been performed with various methods, including blade plates and bone grafting, as well as intramedullary support with autologous or allogenic grafts. Both malunion and nonunion have occurred after ORIF with locking plates. Endosteal support in the form of a fibular allograft incorporated into the locking plate construct can increase mechanical stability in selected cases. An ideal implant for proximal humeral nonunion provides medial column mechanical support and osteoconductive and osteoinductive properties. Porous intramedullary tantalum metal may play a role in nonunion surgery as an alternative to fibular allograft because of its versatility of use and salutary biological effects. It offers many material advantages for use in nonunion surgery. Tantalum is extensively porous (75%-80%), has a stiffness close to that of native bone, and offers the possibility of being a carrier for osteoinductive materials. It may also be suitable for patients who refuse allograft material. This article describes a 65-year-old woman with recalcitrant proximal humeral nonunion who was successfully treated with revision ORIF with intramedullary tantalum cylinder augmentation with a lateral-based locking plate and autogenous cancellous bone grafting. At 5-year follow-up, she had excellent motion and clinical and radiographic union.

Early results of trabecular metal augment for acetabular reconstruction in revision hip arthroplasty

The management of acetabular bone defects presents a challenge in revision total hip arthroplasty (THA). The aim of this study was to assess the early clinical and radiological outcome of revision of acetabular components using trabecular metal cups and augments for acetabular reconstruction. The study included 18 consecutive patients with failed acetabular components after total hip arthroplasty, with acetabular defects that were revised using porous tantalum acetabular components and augments. The mean follow-up was 18 months (range: 12-24). At the most recent follow-up, 6 patients (33%) were graded as having an excellent result, 9 (50%) a good result, 3 (17%) a fair result according to the HHS. The hip centre was restored to its normal position. There were no cases of hip dislocation. One patient had a partial sciatic nerve palsy which had resolved two months postoperatively. Based on these early clinical and radiological results, TM acetabular components and augments for acetabular defects (Paprosky II and III) appear to be a promising solution for this complex situation. We continue to monitor these patients, and a larger series with longer follow-up will be required to determine the long-term outcome of these augments.

[Three-dimensional finite element analysis of acetabular prosthesis in an adult patient with total flip arthroplasty for high dislocation]

OBJECTIVE

To observe stress distributions around the acetabular prosthesis and the bones of a patient who underwent total hip arthroplasty (THA).

METHODS

Finite element analysis (FEA) was performed with an osteoarthritis patient who underwent THA for her secondary hip high dislocations: Scenario A--deepened acetabulum at the true acetabulum with a small 44 mm cup; Scenario B--structural bone graft at lateral acetabular with a 48 mm cup; Scenario C--place tantalum metal acetabular reconstruction at the lateral acetabular with a 48 mm cup; Scenario D--the normal side of the hip. According to the Wasielewski methods, acetabular was divided into four zones, in the same way on the lining surface. Ten points were taken in each zone for measuring the Von Mises stress values.

RESULTS

Scenario A generated significantly greater stress values in the bones in zone one than the other three scenarios. Significantly greater stress was also found in the inner surface of polyethylene over all of the four zones under scenario A compared with those of the scenario B and C, especially in zone one and two. The cup initial micro-mobility for scenario A was 49. 18 microm, 19 times of that of scenario B and 8 times of that of scenario C.

CONCLUSION

(1) Deepened acetabulum with small cup can cause stress concentration in the acetabular bones and liner, leading to large cup initial micro-mobility. (2) Acetabular lateral structural bone grafting and placement of tantalum metal reconstruction have better biomechanical properties, which can enable the use of bigger cups.

Subnanosecond, mid-IR, 0.5 kHz periodically poled stoichiometric LiTaO3 optical parametric oscillator with over 1 W average power

We report a subnanosecond mid-IR tunable optical parametric oscillator based on periodically poled stoichiometric lithium tantalate (PPSLT), pumped by an amplified single frequency microchip laser at 1064 nm at a repetition rate of 0.5 kHz. Using a 20 mm long PPSLT crystal polled with three different domain periods (30.2, 30.3, and 30.4 μm) and changing the temperature of the crystal from 20°C to 265°C, we achieved wavelength tuning between 2990 and 3500 nm. The high nonlinearity of the used medium and the large aperture (3.2 mm) ensure maximum idler output energy of ~2 mJ in the whole tuning range, corresponding to 18% idler conversion efficiency and more than 1 W of average power. 270 ps idler pulse durations were obtained as a result of the 818 ps pulse duration of the pump.

[Short-term curative effects of Tantalum rod treatment in early avascular necrosis]

OBJECTIVE

To explore the recent clinical curative effect of Tantalum rod in treating the early avascular necrosis.

METHODS

From January 2008 to November 2008, the 25 patients (39 hips) with early avascular necrosis accepted tantalum rod placement and included 9 males (11 hips) and 16 females (28 hips) with an average age of 37 years old ranging from 18 to 74 years old. Four patients (6 hips) caused by Alcoholic, 6 patients (8 hips) by hormone, 2 cases (2 hips) by traumatic, 13 cases (23 hips) by idiopathic. Steinberg preoperative stage involved 7 hips in period I, 24 hips in period II, 8 hips in period III. Curative effect analysis included preoperative and postoperative Harris score, radiographic changes and hip replacement for follow-up to accept the end of the femoral head survival rate.

RESULTS

All patients were followed up for 6 to 47 months (averaged 37.4 months). All 12 hips imaging appeard progress,including tantalum rod exit in 1 hip, hip hemiarthroplasty collapse in 3 hips, the area increased to avascular necrosis in 8 hips. Six hips accepted total hip replacement, including imaging progress in 5 hips (41.7%, 5/12), no imaging progress in 1 hip (3.7%,1/27). All hips' Kaplan-Meier survival curves showed 6-month survival rate was (97.4 +/- 2.5)% after tantalum stick insertion, 1-year survival rate was (94.7 +/- 3.6), and 2-year survival rate was (88.6 +/- 5.4)%, 3-year survival rate was (72.5 +/- 11.2).

CONCLUSION

It is effective for treatment of avascular necrosis of femoral head in Steinberg I and II by Tantalum rod, and it can effectively relieve femoral head replacement time.

[Progress on tantalum rod implanting for the treatment of femur head necrosis]

Incorrect treatment for femur head necrosis can cause collapse of femoral head and tresult in severe harm for the patients (especially for the patient with middle-aged and young). The structure and mechanics characteristics of tantalum rod is similar to bone tissue, it higher strength and can adapt the internal environment of organism, so it has a large potency in treating femur head necrosis. Treatment of early femur head necrosis with tantalum rod implanting had alreadly widey applied at home and abroad, the method has the advantages of simple operation, little risk, less complication and beseems the patient with stage I - II of ARCO. But reasons that the difficult diagnosis of early femur head necrosis, localized effect of tantalum rod, different experience of medical worker,caused the contentions about effect of tantalum rod implanting. With development of science, tantalum rod implanting combined with correlative biotechnology should raise the effect in treating femur head necrosis.

Synthesis of coral-like tantalum oxide films via anodization in mixed organic-inorganic electrolytes

We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH₄F and H₂O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two–electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%.

[New type titan alloy with shape memory for use in dental implantology]

The paper summarizes the results of in vitro and in vivo studies that have proved biocompatibility and medical safety of Ta and Ti-Nb-Ta-bases alloys. According to some in vitro data Ti-Nb-Ta-based alloy possesses certain advantages when comparing to Ta-based. In particular, it contributes to elevation of viability of cellular elements and to definite increase of their adhesive potential.

Acetabular distraction: an alternative for severe defects with chronic pelvic discontinuity?

BACKGROUND

Stabilization of a pelvic discontinuity with a posterior column plate with or without an associated acetabular cage sometimes results in persistent micromotion across the discontinuity with late fatigue failure and component loosening. Acetabular distraction offers an alternative technique for reconstruction in cases of severe bone loss with an associated pelvic discontinuity.

QUESTIONS/PURPOSES

We describe the acetabular distraction technique with porous tantalum components and evaluate its survival, function, and complication rate in patients undergoing revision for chronic pelvic discontinuity.

METHODS

Between 2002 and 2006, we treated 28 patients with a chronic pelvic discontinuity with acetabular reconstruction using acetabular distraction. A porous tantalum elliptical acetabular component was used alone or with an associated modular porous tantalum augment in all patients. Three patients died and five were lost to followup before 2 years. The remaining 20 patients were followed semiannually for a minimum of 2 years (average, 4.5 years; range, 2-7 years) with clinical (Merle d'Aubigné-Postel score) and radiographic (loosening, migration, failure) evaluation.

RESULTS

One of the 20 patients required rerevision for aseptic loosening. Fifteen patients remained radiographically stable at last followup. Four patients had early migration of their acetabular component but thereafter remained clinically asymptomatic and radiographically stable. At latest followup, the average improvement in the patients not requiring rerevision using the modified Merle d'Aubigné-Postel score was 6.6 (range, 3.3-9.6). There were no postoperative dislocations; however, one patient had an infection, one a vascular injury, and one a bowel injury.

CONCLUSIONS

Acetabular distraction with porous tantalum components provides predictable pain relief and durability at 2- to 7-year followup when reconstructing severe acetabular defects with an associated pelvic discontinuity.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Histological ex vivo analysis of retrieved human tantalum augmentations

PURPOSE

The characteristics of tantalum augment osseointegration in human ex vivo specimens from re-revision procedures are unknown and limited data in this regard is available. The purpose of this study was to investigate the osseointegration pattern into porous tantalum augmentations harvested during re-revision procedures.

METHODS

Between 2007 and 2010 a total of 324 hip and knee revisions with a tantalum augmentation were performed in our institution. Out of this cohort, seven patients (2.2 %) had to be re-revised. To analyse the status of trabecular ingrowth in the retrieved cases (four hips, three knees), all specimens were analysed by contact radiography, subjected to undecalcified processing, histology, thin-section analysis and backscattered electron imaging.

RESULTS

Trabecular and vascular ingrowth could be found along the bone-augment-interface in two of seven revised specimens, respectively. The depth of bone ingrowth reached up to 2.6 mm. However, the analysis of the remaining cases revealed no bony ingrowth into trabecular metal. Rather, large parts of the implants were embedded in cement or pores were filled with autologous bone.

CONCLUSIONS

Although the cause for the missing bony ingrowth seems to be multifactorial, some fundamental conditions, such as the provision of the greatest possible interface between the tantalum implant and the host bone, should be met and thus, bone cement and autologous bone grafts should be used with caution.

Expression of interleukin 6 and tumor necrosis factor alpha in soft tissue over ceramic and metal implant materials before uncovering: a clinical pilot study

PURPOSE

To compare the effect of ceramic and metal implant materials on the expression pattern of inflammatory cytokines in peri-implant soft tissue.

MATERIALS AND METHODS

This split-mouth study included patients who received dental implants. In each patient, four different materials were used for the implant cover screws: the ceramic material titanium niobium oxynitride ([Ti,Nb]ON) with plasma-chemical oxidation treatment, (Ti,Nb)ON, a titanium-tantalum alloy, and tantalum. Biopsy specimens of peri-implant tissue were harvested at reentry, 4 months after the initial surgery. Immunohistochemical staining was performed for tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6).

RESULTS

Six patients received a total of 24 dental implants with the four different types of implant cover screws. Quantitative analysis of TNF-α; and IL-6 expression showed the lowest expression of IL-6 (1.5; interquartile range, 0 to 8.5) and TNF-α (4.8; interquartile range, 3.5 to 7.5) in tissue adjacent to the (Ti,Nb)ON layer. In comparison to the metal surfaces, the expression of both cytokines was significantly lower (P = .01 and P = .03).

CONCLUSIONS

The lowest levels of cytokine expression were observed in tissue adjacent to the ceramic (Ti,Nb)ON coating with plasma-chemical oxidation. Based on the results of this study, this ceramic layer shows promise as a biocompatible material, and further study is warranted.

Evaluation of mandibular growth using cone-beam computed tomography in a rabbit model: a pilot study

OBJECTIVES

The aim of this pilot study was to describe three-dimensional (3D) changes during mandibular growth in a rabbit model using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

CBCT scans were taken of three growing New Zealand white rabbits at baseline and then fortnightly for eight weeks. Metallic tantalum 1-mm spheres were implanted as bone reference markers. 3D images were constructed, and mandibular growth was described by six measurements.

RESULTS

The animals coped well with the experimental procedures. The use of CBCT to evaluate 3D mandibular growth appeared feasible in this rabbit model. Consistent mandibular growth (of 0.6 to 5.7 mm) was observed in all rabbits. Distances between the bone markers changed slightly (0.0 to 1.6 mm).

CONCLUSION

During the observation period, vertical ramus growth in the rabbit mandible was more prominent than either sagittal or transverse growth. The mandibular molar region seemed to be the most stable area for radiographic superimposition in the rabbit model. 3D evaluation of mandibular growth in a rabbit model using CBCT represents a promising approach for the preclinical evaluation of proposed treatment intervention studies.

Tantalum augments for Paprosky IIIA defects remain stable at midterm followup

BACKGROUND

Initial reports with short-term followup of porous tantalum acetabular components and augments for Paprosky IIIA acetabular defects demonstrate high hip scores, low rates of aseptic loosening, and low rates of complications. However, longer-term followup with a larger cohort is needed to determine the durability of these reconstructions.

QUESTIONS/PURPOSES

We therefore determined the functional scores, rates of aseptic loosening, and complications in patients with Paprosky IIIA acetabular defects treated with porous tantalum acetabular components and augments.

METHODS

We retrospectively reviewed 37 acetabular revisions in 36 patients (one patient with bilateral revisions) treated with a porous tantalum acetabular component and augment. All patients had defects classified as Type IIIa using the system of Paprosky et al. Harris hip scores were obtained and radiographic examination was performed before surgery and through most recent followup. The minimum followup was 26 months (mean, 60 months; range, 26-106 months).

RESULTS

One patient developed aseptic loosening of the acetabular reconstruction requiring revision; seven other patients required further surgery for periprosthetic femoral fracture (two), acute infection (three), and recurrent dislocation (two). Thirty-five of 37 hips had no or occasional pain at final followup. Mean Harris hip scores improved from 33.0 preoperatively (range, 12.6-58.7) to 81.5 postoperatively (range, 27.0-99.8).

CONCLUSIONS

Although the complication rate requiring further surgery was considerable, most patients with these reconstructions had pain relief and reasonable function with low rates of loosening at midterm followup.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

[Application of porous tantalum implant in treatment of bone defect]

OBJECTIVE

To review the progress in the treatment of bone defect by porous tantalum implant.

METHODS

Recent literature was extensively reviewed and summarized, concerning the treatment method of bone defect by porous tantalum implant.

RESULTS

By right of their unique properties, porous tantalum implants have achieved very good results in the treatment of certain types of bone defects.

CONCLUSION

Porous tantalum implants have their own advantages and disadvantages. If the case is meet to its indications, this method can obtain a good effect. Porous tantalum implants provide a new way for the clinical treatment of bone defects.

[Status of the cardiorespiratory system of workers at modern tantalum manufacturer]

Cardiorespiratory state in contemporary tantalum production workers was studied according to central hemodynamic parameters and pulmonary ventilation values. Specific changes in these parameters and values depend on conditions and character of work in tantalum production. Preventive measures help to reduce risk of cardiovascular and respiratory diseases.

[Treatment of avascular necrosis of the femoral head by lesions clearance, compact bone grafting, and porous tantalum rod implantation]

OBJECTIVE

To study the effectiveness of avascular necrosis of the femoral head treated by lesions clearance,

METHODS

Between March 2008 and May 2010, 14 patients (16 compact bone grafting, and porous tantalum rod implantation. hips) with avascular necrosis of the femoral head were treated by lesions clearance, compact bone grafting, and implantation of porous tantalum rod. Of 15 cases, 13 were male (15 hips) and 1 was female (1 hip) with a median age of 42.2 years (range, 18-73 years), including traumatic in 1 case (1 hip), alcoholic in 4 cases (4 hips), and steroid-induced in 9 cases (11 hips); 3 hips were at Association Research Circulation Osseous (ARCO) stage I and 13 hips were at ARCO stage II. The Harris score was 51.89 +/- 12.42, and the X-ray score was 31.88 +/- 4.03. All the cases were diagnosed by X-ray films and MRI. The median disease duration was 2.5 years (range, 6 months to 7 years). All the patients accepted the operation of lesions clearance by slotting at the neck of femur, then, compact bone grafting, and implantation of porous tantalum rod were performed. The affected limb could not bear weight loading at 1-3 months after operation and partly bear weight loading after 3 months of operation.

RESULTS

Primary healing of incision was achieved in all patients and no complication occurred. The patients were followed up 24 months on average (range, 13-36 months). Two patients underwent total hip arthroplasty at 4 months and 2 years respectively because of even worsened pain and collapsed femoral heads; 12 patients achieved obvious pain relief with a survival rate 87.5% (14/16). The postoperative Harris score was 84.89 +/- 17.96, showing significant difference when compared with preoperative score (t = -8.038, P = 0.001). The X-ray examination showed definite ossification, increased density, regular arrangement of the trabeculae and no collapsed femoral head. The X-ray score was 32.19 +/- 6.57, showing no significant difference when compared with preoperative score (t = -2.237, P = 0.819).

CONCLUSION

Lesions clearance, compact bone grafting, and implantation of porous tantalum rod for avascular necrosis of the femoral head have a good short-term clinical result.

[Treatment of adult early femur head necrosis with the tantalum screw]

OBJECTIVE

To investigate a new method for the treatment adult early femur head necrosis in order to avoid further collapse and necrosis and improve the clinical symptoms.

METHODS

From January 2009 to June 2010, 10 hips of 9 patients, including 7 males and 2 females, aged from 29 to 63 years old (averaged 44.1), with femur head necrosis were treated with implantation of the tantalum screw. The X-ray film, CT scan and MRI were performed before operation. According to Steinberg staging, stage I was in 1 case (1 hip), stage II a in 4 cases(5 hips), stage II b in 4 cases (4 hip). With the C-arm X-ray conducted guide, wire was drilled into the center of femur head necrosis regions from the greater trochanter bottom, hollow bodkin enlarged marrow along the guide wire, scraped necrosis sequestrum, transplanted bone if necessary,then implantated the appropriate tantalum screw to prop up the articular surface. The patients were followed up at 3rd, 6th, 9th month postoperatively, the clinical effects were evaluated according to the JOA criteria, and the changes of the femoral head were observed by X-rays.

RESULTS

The mean operative time was 50 min (ranged from 40 to 60 min); the mean blood loss was 80 ml (ranged from 60 to 100 ml). There was no complications, such as postoperative infection, fracture, deep vein thrombosis and so on. All patients were followed up more than 9 months. No aggravation in collapse and necrosis were found by regular X-ray examination. Post-operative JOA score increased month by month. JOA scores increased obviously from preoperative (31.30 +/- 19.63) to (54.10 +/- 13.20), (69.90 +/- 15.04), (87.00 +/- 8.83) at the 3,6,9 months after operation, respectively.

CONCLUSION

The tantalum screw implantation is simple and effective for the treatment of adult early femur head necrosis, and can effectively avoid collapse of necrotic area, the results were satisfactory in the near future.

Subtrochanteric femur fracture after core decompression and placement of a tantalum strut for osteonecrosis of the femoral head

Multiple treatment options have been described to treat osteonecrosis of the femoral head, all with the goal of slowing or reversing the disease process and preventing the need for arthroplasty in a young patient population. Core decompression of the femoral head to allow revascularization is a commonly used technique that can now be supplemented by placement of the Osteonecrosis Intervention Implant (Zimmer, Warsaw, Ind). It consists of a tantalum strut that acts as a buttress for the subchondral bone of the femoral head. In this case, our patient underwent this procedure with subsequent subtrochanteric fracture. The factors leading to this iatrogenic injury are location of implant insertion, patient selection, and premature ambulation.

Bone remodeling around porous metal cementless acetabular components

Bone remodeling around cementless acetabular components after total hip arthroplasty has not been well characterized. A randomized, prospective study of total hip arthroplasty was performed comparing 2 cementless acetabular implants: a solid titanium and a more elastic porous tantalum design. Seventeen hips (9 porous tantalum, 8 titanium) underwent quantitative computed tomography at mean of 7.7 years, and adjacent bone mineral density (BMD) was calculated. The absolute and relative decrease in BMD from preoperative level was less in zones 9 to 15 mm adjacent to the porous tantalum compared to the titanium component (P <or= .02) and predominated posterosuperiorly. The relative BMD increased in all regions adjacent to the porous tantalum component from 5% to 40% over the control. This data demonstrates stress-shielding likely occurs less around a highly porous metal implant of material with an elastic modulus similar to bone.

Peculiarities of circulatory system response on influence of modern tantalum manufacture factors in workers

Objective of this study was to examine functional condition of cardiovascular system among workers at "Ulba Metallurgical Plant" JSC (located in Ust-Kamenogorsk, Eastern Kazakhstan)--one of the world largest enterprises with the full production cycle from processing of tantalum containing raw materials to finished products. All workers that participated in the examination were divided into three groups: (I)--up to 5 years of occupation; (II)--from 5 to 9.9 years of occupation; and (III)--more than 10 years of occupation experience in the tantalum industry. The cardiovascular system, health concern and their contributing factors were assessed. In group I the factor of profitability of blood circulation was up to 3000 conventional units, which corresponds to the optimal fatigue; In group II the factor of profitability of blood circulation was increased up to 3525±327,3 conv. units--critical values zone. In group III the factor of profitability of blood circulation was up to 3000 conv. units. A relative improvement in the central hemodynamic indices compared with those in group II may be due to the development of adaptation. The assessments of functional condition of cardiovascular system among the workers specialize in different stages of tantalum production revealed the necessity of paying special attention at the cycle of tantalum processing and the years of work experience in an occupation.

Single-pass sum-frequency-generation of 589-nm yellow light based on dual-wavelength Nd:YAG laser with periodically-poled LiTaO(3) crystal

We demonstrate a compact all-solid-state yellow laser source based on Q-switched dual-wavelength Nd:YAG laser and periodically-poled LiTaO(3) crystal. 589-nm yellow light was generated by single-pass sum-frequency generation of the fundamental IR waves at 1064 and 1319 nm. The maximum output power of yellow light was 506 mW and the corresponding conversion efficiency was approximately 5.5% [W(-1)cm(-1)].

Case report: reconstruction of the distal tibia with porous tantalum spacer after resection for giant cell tumor

Treatment options for giant cell tumors of the distal tibia include curettage and cement packing, curettage and bone grafting, or resection and reconstruction for aggressive tumors. Curettage of aggressive tumors often leads to severe bone loss requiring reconstruction. Allograft and autograft may be effective options for reconstruction, but each is associated with drawbacks including the possibility of infection and collapse. We present a case of giant cell tumor of the distal tibia treated with curettage and arthrodesis using a porous tantalum spacer. Complete removal of the tumor and successful arthrodesis of the ankle were accomplished using the spacer. The patient returned to pain-free walking along with eradication of the giant cell tumor. We believe porous tantalum spacers are a reasonable option for reconstructing the distal tibia after curettage of a giant cell tumor with extensive bone loss.

Photocatalytic activities for hydrogen evolution of new layered compound series HLaTa(x/3)Nb2-x/3O(7)/Pt (x=0, 2, 3, 4, and 6)

HLaTa(x/3)Nb(2-x/3)O(7) were synthesized by successive reactions of conventional solid-state reaction followed by ion exchange reaction. They were characterized by power X-ray diffraction, UV-vis diffusive reflectance and scan electron microscope. The effect of substitution of Ta for Nb in HLaNb(2)O(7) has been studied on the photocatalytic decomposition of water under UV light irradiation with methanol as electron donor and Pt as promoter catalyst. The x value in HLaTa(x/3)Nb(2-x/3)O(7) had an important effect on the photocatalytic activity of the catalyst. When x=2, HLaTa(2/3)Nb(4/3)O(7)/Pt shows a photocatalytic activity of 136 cm(3)g(-1)h(-1) hydrogen evolution in rate 10 vol.% methanol aqueous solution under irradiation with wavelength more than 290 nm from a 100-W mercury lamp.

Vacuum-deposited wave-guiding layers on STW resonators based on LiTaO(3) substrate as love wave sensors for chemical and biochemical sensing in liquids

A promising approach to apply the Love wave concept to commercially available low-loss surface acoustic wave (SAW) devices of the type Murata SAF 380 is presented. Thin wave-guiding layers of variable thickness are coated on the piezoelectric substrate of the devices. Two different layer materials were used: sputtered SiO(2) and a new polymer in this field, paryleneC (poly-[2-chloro-p-xylylene]). Insertion loss, resonance frequency, frequency changes during protein precipitation and noise of the devices are discussed as a function of the thickness of the wave-guiding layer. It is demonstrated that the application of an optimized wave-guiding layer increases the sensitivity. When using SiO(2) as wave-guiding layer, an optimum layer thickness of 4 microm leads to a detection limit of 1.7 pg/mm(2). Therefore, the detection limit is improved by factor 7.7 as compared to uncoated SAW devices. Parylene-coated devices reach a detection limit of 2.9 pg/mm(2) at an optimum layer thickness of 0.5 microm. This corresponds to an improvement by factor 4.3. As the SAW devices used in this study are commercially available at low costs, applying appropriate wave-guiding layers permits an application as chemical or biochemical sensors with excellent sensitivities. Moreover, parylene-coated devices combine the sensitivity increase by excitation of Love waves with an excellent protective effect against corrosive attacks by the surrounding medium. Therefore, these sensors are most suitable for biosensing in conducting buffer solutions.