Infection associated with hydroxyapatite prosthesis and related factors

Background The purpose of otomicrosurgery in modern times is to achieve complete removal of disease, which is the basis for hearing rehabilitation. Artificial ossicles are important for hearing rehabilitation. One of the materials is hydroxyapatite that acts as ossicular replacement prosthesis (HA prosthesis, PORP & TORP) and is commonly used as substitute bone in clinics. Although HA prostheses feature good biocompatibility, stability and certain resistance to infection, the structure of the material can be decomposed and absorbed. Based upon animal experiments and clinical application, this article explores the infectivity of HA prostheses and influencing factors. Materials and Methods HA prostheses were implanted in the bulla in guinea pigs. Infected HA prostheses were examined under a scanning electron microscope. Ninety patients implanted with HA prostheses were followed for more than 3 months. Five cases that had undergone revision operations were reported. Results Scanning electronic microscopy showed that the normal compact structures had disappeared and become loose in infected HA prostheses, with their micropores infiltrated with effusion, fibrous tissue and inflammatory cells. As a result, the normal ceramic structure was decomposed and the micropores structure disappeared. The infected mesotympanum in the reported cases also led to HA infection. The shape and structure of bone were destroyed, which was visible by visual examination and light microscopy. The process of cholesteatoma recurrence was always associated with infection, although the HA prosthesis was sometimes spared. Conclusion While HA prosthesis is anti-infective to some extent, long-term infection and cholesteatoma recurrence can lead to destruction and decomposition of HA prostheses. Long-term infected middle ear cavity, dysfunctional Eustachian tube, residual and recurrent cholesteatoma and other factors can cause decomposition of HA prosthesis and result in hearing loss.

Indication and surgical approach for reconstruction with endoprosthesis in bone-associated soft tissue sarcomas:Appropriate case management is vital

It is important for surgeons performing sarcoma surgery to know that bone resection and tumor prosthesis applications in soft tissue sarcomas(STS)have unique features in terms of indication,surgical approach and follow-up,in terms of the management of these cases.Some STS are associated with bone and major neurovascular structures.Bone-associated STS are generally relatively large and relatively deep-seated.Additionally,the tendency for metastasis is high.In some cases,the decision about which structures to resect is difficult.These cases are often accompanied by poor oncological and surgical outcomes.Management of cases should be done by a multidisciplinary team in advanced centers specialized in this field.The surgical team must have sufficient knowledge and experience in the field of limb-sparing surgery.Preoperative evaluation and especially good planning of bone and soft tissue reconstruction are vital.

Effect of Wearing a Maxillofacial Prosthesis on Masticatory Rhythm Improvement in Mandibulectomy Patients

Background: Recording jaw movement rhythms in patients with jaw defects is challenging using conventional tracking devices. However, masticatory rhythm is crucial for masticatory performance and nutritional intake. This study aimed to explore the impact of using a maxillofacial prosthesis to restore masticatory rhythm in mandibulectomy patients with a novel wearable device. Methods: Twelve patients who underwent mandibulectomy and were rehabilitated with maxillofacial prosthesis were recruited. Chewing rate, cycle durations, coefficient of variation of cycle durations (CV), changing times of skin morphology on the back of the ear pinna area (SM), and masticatory performance were measured during gum chewing without and with a denture using a wearable jaw movement rhythm tracking device. A paired t-test and the Pearson correlation coefficient were used for statistical analysis. Results: The chewing rate increased by 8.6 cycles/min with dentures (P P = 0.01). The CV and SM decreased with dentures (P = 0.004 and P = 0.01, respectively). Significant correlations were found between the CV and SM without dentures (P = 0.004). Conclusion: 1. Wearing maxillofacial prostheses can improve masticatory rhythm in patients who undergo mandibulectomy with Eichner B2 occlusal supports. 2. The wearable device is available for measuring masticatory rhythm in patients with jaw defects in clinics. 3. Changing times of the skin morphology on the back of the ear pinna indicate jaw movement stability through a simpler process than the coefficient of variation of cycle durations.

Transfer film effects induced by 3D-printed polyether-ether-ketone with excellent tribological properties for joint prosthesis

Based on the building principle of additive manufacturing,printing orientation mainly determines the tribological properties of joint prostheses.In this study,we created a polyether-ether-ketone(PEEK)joint prosthesis using fused filament fabrication and investigated the effects of printing orientation on its tribological properties using a pin-on-plate tribometer in 25% newborn calf serum.An ultrahigh molecular weight polyethylene transfer film is formed on the surface of PEEK due to the mechanical capture of wear debris by the 3D-printed groove morphology,which is significantly impacted by the printing orientation of PEEK.When the printing orientation was parallel to the sliding direction of friction,the number and size of the transfer film increased due to higher steady stress.This transfer film protected the matrix and reduced the friction coefficient and wear rate of friction pairs by 39.13%and 74.33%,respectively.Furthermore,our findings provide a novel perspective regarding the role of printing orientation in designing knee prostheses,facilitating its practical applications.

Hydroxyapatite coating on pretreated CoNiCrMo prosthesis

In order to improve the quality of the bio-active coating on medical grade CoNiCrMo substrate, hydroxyapatite(HA) coatings were produced via low-temperature dip-coating route on substrates treated using various surface pre-treating methods. The surface and cross-sectional morphologies of HA coatings were observed by SEM, as well as the bonding strength between coatings and substrates after different pre-treatments were characterized according to ASTM C633. The low-temperature HA dip-coating method with the substrate merely oxidized at 600℃ can provide a high quality HA coating for CoNiCrMo, of which the bonding strength reaches (58±5)MPa, higher than that of the clinically used HA coatings on Ti-alloys produced via plasma spray route, as well as a HA coating with full crystallinity and high phase-purity, which is more in-vivo stable than plasma sprayed HA coating.

Bio-inspired Hydroxyapatite/Gelatin Transparent Nanocomposites

Hydroxyapatite(HA)nanoparticles impart outstanding mechanical properties to organicinorganic nanocomposites in bone.Inspired by the composite structure of HA nanoparticles and collagen in bone,a high performance HA/gelatin nanocomposite was first developed.The nanocomposites have much better mechanical properties(elongation at break 29.9%,tensile strength 90.7 MPa,Young’s modulus 5.24 GPa)than pure gelatin films(elongation at break 9.3%,tensile strength 90.8 MPa,Young’s modulus 2.5 GPa).In addition,the composite films keep a high transmittance in visible wavelength range from 0%to 60%of the HA solid content.These differences in properties are attributed to the homogeneous distribution of HA nanoparticles in the gelatin polymer matrix and the strong interaction between the particle surfaces and the gelatin molecules.This protocol should be promising for HA-based nanocomposites with enhanced mechanical properties for biomedical applications.

Effect of Fluoride on the Ion-association of Calcium Phosphate and Crystallization of Hydroxyapatite

Using a titration setup to accurately control the reaction conditions and in situ monitor the reaction,we showed that fluoride exhibited negligible effects on the ion association process of calcium and phosphate and the formation of ACP nanospheres in a buffer solution with constant ionic strength.However,the stability of ACP increased with increasing fluoride concentration,which was ascribed to the inhibitory effect of fluoride on the aggregation of ACP nanospheres and the nucleation of nanocrystals on the surface of ACP nanospheres.Furthermore,fluoride could inhibit the lateral growth of HAP nanosheets and promote the formation of rod-like crystals.These results further improve our understanding of the crystallization pathway of HAP crystals and the regulatory effects of fluoride.

Ionic liquid-assisted preparation of hydroxyapatite and its catalytic performance for decarboxylation of itaconic acid

The synthesis of methacrylic acid from biomass-derived itaconic acid is a green route,for it can get rid of the dependence on fossil resource.In order to solve the problems on this route such as use of a preciousmetal catalyst and a corrosive homogeneous alkali,we prepared a series of hydroxyapatite catalysts by an ionic liquid-assisted hydrothermal method and evaluated their catalytic performance.The results showed that the ionic liquid[Bmim]BF_(4) can affect the crystal growth of hydroxyapatite,provide fluoride ion for fluorination of hydroxyapatite,and adjust the surface acidity and basicity,morphology,textural properties,crystallinity,and composition of hydroxyapatite.The[Bmim]BF4 dosage and hydrothermal temperature can affect the fluoride ion concentration in the hydrothermal system,thus changing the degree of fluoridation of hydroxyapatite.High fluoride-ion concentration can lead to the formation of CaF_(2) and thus significantly decrease the catalytic performance of hydroxyapatite.The hydrothermal time mainly affects the growth of hydroxyapatite crystals on the c axis,leading to different catalytic performance.The suitable conditions for the preparation of this fluoridized hydroxyapatite are as follows:a mass ratio of[Bmim]BF4 to calcium salt=0.2:1,a hydrothermal time of 12 h,and a hydrothermal temperature of 130℃.A maximal methacrylic acid yield of 54.7%was obtained using the fluoridized hydroxyapatite under relatively mild reaction conditions(250℃ and 2 MPa of N_(2))in the absence of a precious-metal catalyst and a corrosive homogeneous alkali.

Characterization of Hydroxyapatite Extracted from Crab Shell Using the Hydrothermal Method with Varying Holding Times

Hydroxyapatite(HA)is a bio ceramic commonly utilized in bone tissue engineering due to its bioactive and osteoconductive properties.Crab shells are usually disregarded as waste material despite their significant CaCO_(3) content,and have not been widely utilized in the synthesis of HA.This study aims to synthesize and analyze HA derived from crab shells using the hydrothermal method with different durations of holding time.This study utilized precipitated calcium carbonate(PCC)derived from crab shells.With a hydrothermal reactor set at 160℃ and varying holding times of 14(HA_14),16(HA_16),and 18(HA_18)h,a PCC and(NH4)2HPO4 mixture was used to synthesize HA.The synthesis results were analyzed using scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)tests.This study has accomplished the synthesis of HA from crab shells.Nonetheless,the final product of synthesis still contained CaCO_(3) as an impurity.The prolonged hydrothermal holding time of 14 to 18 h resulted in a reduction of impurities while increasing the percentage of crystal weight and crystallite size of HA.Specimen CH_18 is the best-quality product generated in this study.This specimen produced HA with the highest percentage of crystal weight and crystallite size compared to the other specimens.Furthermore,specimen CH_18 exhibited the lowest concentration of impurities.The Ca/P ratio in this specimen was also the closest to 1.67.The Ca/P ratio,crystallite size,and crystal weight percentage of this specimen are 1.54,19.06 nm,and 99.1%,respectively.

Influence of anodization conditions on deposition of hydroxyapatite onα/βTi alloys for osseointegration:Atomic force microscopy analysis

Integrating titanium-based implants with the surrounding bone tissue remains challenging.This study aims to explore the impact of different anodization voltages(20−80 V)on the surface topography of two-phase(α/β)Ti alloys and to produce TiO_(2) films with enhanced bone formation abilities.Scanning electron microscopy coupled with energy dispersive spectroscopy(SEM−EDS)and atomic force microscopy(AFM)were applied to investigate the morphological,chemical,and surface topography of the prepared alloys and to confirm the growth of hydroxyapatite(HA)on their surfaces.Results disclosed that the surface roughness of TiO_(2) films formed on Ti−6Al−7Nb alloys was superior to that of Ti−6Al−4V alloys.Ti−6Al−7Nb alloy anodized at 80 V had the highest yields of HA after immersion in simulated body fluid with enhanced HA surface coverage.The developed HA layer had a mean thickness of(128.38±18.13)μm,suggesting its potential use as an orthopedic implantable material due to its promising bone integration and,hence,remarkable stability inside the human body.

Retinal Prosthesis:A Potential Benefit for the Blind

Retinal degenerative diseases may induce the degeneration of outer retina and in turn,blindness.Nevertheless,due to the maintenance of inner retina,the coding and processing of visual neurons responses are still able to be executed naturally.Therefore,an effective retinal prosthesis device may be developed by mimicking the function of outer retina:transferring the visual light into artificial stimulus and delivering the stimulus to the retina aiming to evoke the neural responses.As two main developing directions for current retinal prosthesis,epiretinal(ER)and subretinal(SR)prosthesis are both undergoing experimental stage and possessing advantages and limitations.Further investigations in power supply,biocompatibility,etc.are still required.Additionally,suprachoroidal transretinal stimulation(STS)and neurotransmitter-induced stimulation as some other alternatives in retinal prosthesis are also considered as promising research directions,although they are not mature enough to be applied commercially,either.

Development and clinical application of a new testicular prosthesis

A new type of testicular prosthesis made of silastic with an elliptical shape to mimic a normal testis was developed by our team and submitted for patenting in China. The prosthesis was produced in different sizes to imitate the normal testis of the patient. To investigate the effects and safety of the testicular prosthesis, 20 patients receiving testicular prosthesis implantation were recruited for this study. Follow-up after 6 months revealed no complications in the patients. All the patients answered that they were satisfied with their body image and the position of the implants, 19 patients were satisfied with the size and 16 patients were satisfied with the weight. These results show that the testicular prosthesis used in this study can meet patient＇s expectations. Patients undergoing orchiectomy should be offered the option to receive a testicular prosthesis implantation. The dimensions and weight of the available prosthetic implants should be further addressed to improve patient satisfaction.

Flexoelectricity in hydroxyapatite for the enhanced piezocatalytic degradation of phenanthrene in soil

Coupling the effects of flexoelectricity with piezoelectricity has been proved to effectively harvest mechanical energy.In this study,a composition-graded core–shell structure(HAP@FAP)was prepared by surface-gradient F-doping in hydroxyapatite,which could introduce flexoelectricity by a built-in strain gradient.A flexoelectric-boosted piezoelectric response was demonstrated by piezoresponse force microscopy(PFM)characterization,showing that the piezoelectric constant of HAP@FAP was increased by 2.25 times via a lattice strain gradient induced by chemical heterogeneities derived from the unique composition-graded core-shell structure.Thus,the piezocatalytic activity of HAP@FAP for phenanthrene(PHE)degradation in soil was enhanced.This work provides a new strategy for the modification of piezoelectric catalysts for the remediation of organics-contaminated soils on industrial land.

In-vitro degradation behavior of Mg alloy coated by fluorine doped hydroxyapatite and calcium deficient hydroxyapatite

Fluorine-doped hydroxyapatite(FHA) and calcium deficient hydroxyapatite(CDHA) were coated on the surface biodegradable magnesium alloy using electrochemical deposition(ED) technique. Coating characterization was investigated X-ray diffraction(XRD), Fourier-transformed infrared spectroscopy(FTIR), transmission electron microscopy(TEM), scanni electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS). The result shows that nano-FHA coated samp presents nano needle-like structure, which is oriented perpendicular to the surface of the substrate with denser and more unifo layers compared to the nano-CDHA coated sample. The nano-FHA coating shows smaller crystallite size(65 nm) compared to t nano-CDHA coating(95 nm); however, CDHA presents thicker layer(19 μm in thickness) compared to the nano-FHA(15 μm thickness). The corrosion behaviour determined by polarization, immersion and hydrogen evolution tests indicates that the nano-FH and nano-CDHA coatings significantly decrease corrosion rate and induce passivation. The nano-FHA and nano-CDHA coatings c accelerate the formation of bone-like apatite layer and significantly decrease the dissolution rate as compared to the uncoated M alloy. The nano-FHA coating provides effective protection to Mg alloy and presents the highest corrosion resistance. Therefore, t nano-FHA coating on Mg alloy is suggested as a great candidate for orthopaedic applications.

Ocular prosthesis incorporating IPS e-max press scleral veneer and a literature review on non-integrated ocular prosthesis

The article highlights a new method for the fabrication of an ocular prosthesis by the incorporation of a ceramic scleral veneer. The steps of fabrication include impression making, wax try-in, performing a “cut-back” on a selected stock eye, insertion of the IPS e-max press scleral veneer, finishing and insertion. It also includes a detailed review on non-integrated ocular prostheses.

An Optoelectronic Pulse Frequency Modulation Circuit for Retinal Prosthesis

A pulse frequency modulation（PFM） circuit for retinal prosthesis,which generates electrical pulses with frequency proportional to the intensity of incident light, is presented. The fundamental characteristic of the circuit is described and analyzed. The circuit is realized in 0.6μm CMOS process,and the simulation results testify to the possibility of sub-retinal implantation.

REALIZATION OF ALGORITHM OF TOOL PATH GENERATION FOR NC MACHINING OF MOLAR PROSTHESIS

The CAD model of molar prosthesis is usually stored in standard templete library （STIr） format. A new topological structure is given based on STL format and the vertex-based entity offset algorithm is presented to realize the rapid generation of roughing/finishing tool path for molar prosthesis. Simulation results show that the proposed algorithm prossesses characteristics of excellent stabilization, fast calculation speed and high machining accuracy.

Development of an internally braced prosthesis for total talus replacement

Total loss of talus due to trauma or avascular necrosis,for example,still remains to be a major challenge in foot and ankle surgery with severely limited treatment options.Implantation of a custom made total talar prosthesis has shown promising results so far.Most important factors for long time success are degree of congruence of articular surfaces and ligamentous stability of the ankle.Therefore,our aim was to develop an optimized custom made prosthesis for total talus replacement providing a high level of primary stability.A custom made hemiprosthesis was developed using computed tomography and magnetic resonance imaging data of the affected and contralateral talus considering the principles and technology for the development of the S.T.A.R.prosthesis(Stryker).Additionally,four eyelets for fixation of artificial ligaments were added at the correspondent footprints of the most important ligaments.Two modifications can be provided according to the clinical requirements:A tri-articular hemiprosthesis or a bi-articular hemiprosthesis combined with the tibial component of the S.T.A.R.total ankle replacement system.A feasibility study was performed using a fresh frozen human cadaver.Maximum range of motion of the ankle was measured and ligamentous stability was evaluated by use of standard X-rays after application of varus,valgus or sagittal stress with 150 N.Correct implantation of the prosthesis was technically possible via an anterior approach to the ankle and using standard instruments.Malleolar osteotomies were not required.Maximum ankle dorsiflexion and plantarflexion were measured as 22-0-28 degrees.Maximum anterior displacement of the talus was 6 mm,maximum varus tilt 3 degrees and maximum valgus tilt 2 degrees.Application of an internally braced prosthesis for total talus replacement in humans is technically feasible and might be a reasonable procedure in carefully selected cases with no better alternatives left.

Tissue Sparing Surgery and Its Relevance within Hip Prosthesis

The total hip replacement rationale, since 1960 when it was introduced by Sir Charnley, has been modified and evolved until nowadays thanks to laboratory research and clinical trials. This evolution followed a guideline whose milestones are: 1) the surgical approach and implantation technique (ex: detachment of the greater trochanter);2) to use or not to use cement;3) the evolution of materials (titanium, ceramic, x-linked polyethylene);4) the identification of the debris-disease rather than the cement-disease;5) studies focused on bone-prosthesis interaction and biological phenomena related. Between those studies, the authors consider crucial the introduction of tissue sparing surgery and femoral neck preserving rationale, concepts to which they have devoted their scientific research and clinical experience for over the last 30 years, from 1980 to nowadays.

Effect of cetyltrimethylammonium bromide on morphology and porous structure of mesoporous hydroxyapatite

The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.