Spinal Implants: Are We Evaluating Them Properly? (Astm Special Technical Publication, 1431.)

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Purified 1-octanol is to be used to prepare standard solutions of the test substances. Water to be used in the P OW determination should be glass or quartz distilled, or obtained from a purification system, or HPLC-grade water may be used. Both solvents are mutually saturated prior to the experiment by equilibrating them in a sufficiently large vessel.

This is accomplished by slow-stirring the two-phase system for two days. An appropriate concentration of test substance is selected and dissolved in 1-octanol saturated with water.

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The 1-octanol solutions used for the experiment must be devoid of suspended solid test substance. The appropriate amount of test substance is dissolved in 1-octanol saturated with water. If the estimate of log P OW exceeds five, care has to be taken that the 1-octanol solutions used for the experiment are devoid of suspended solid test substance. During the settling period, the concentration of the test substance is monitored;.

If the measured concentration is consistent with the dilution, the diluted stock solution can be employed in the slow-stirring experiment. Extraction and analysis of samples. A validated analytical method should be used for the assay of test substance. The investigators have to provide evidence that the concentrations in the water saturated 1-octanol as well as in the 1-octanol saturated water phase during the experiment are above the method limit of quantification of the analytical procedures employed.

Analytical recoveries of the test substance from the water phase and from the 1-octanol phase need to be established prior to the experiment in those cases for which extraction methods are necessary. The analytical signal needs to be corrected for blanks and care should be taken that no carry-over of analyte from one sample to another can occur.

Extraction of the water phase with an organic solvent and preconcentration of extract are likely to be required prior to analysis, due to rather low concentrations of hydrophobic test substances in the water phase. For the same reason it is necessary to reduce eventual blank concentrations. To that end, it is necessary to employ high purity solvents, preferably solvents for residue analysis.

Moreover, working with carefully pre-cleaned e. An estimate of log P OW may be obtained from an estimation program or by expert judgment. If the value is higher than six then blank corrections and analyte carry-over need to be monitored closely. Similarly, if the estimate of log P OW exceeds six, the use of a surrogate standard for recovery correction is mandatory, so that high preconcentration factors can be reached.

Descriptions of the estimation approaches can be found in references The limits of quantification LOQ for determination of the test substance in 1-octanol and water are established using accepted methods. As a rule of thumb, the method limit of quantification can be determined as the concentration in water or 1-octanol that produces a signal to noise ratio of ten. A suitable extraction and pre-concentration method should be selected and analytical recoveries should also be specified. A suitable pre-concentration factor is selected in order to obtain a signal of the required size upon analytical determination.

On the basis of the parameters of the analytical method and the expected concentrations, an approximate sample size required for an accurate determination of the compound concentration is determined. The use of water samples that are too small to obtain a sufficient analytical signal should be avoided. In Appendix 1, the minimum sample volume is indicated as a function of the vessel volume, the LOD of the test substance and the solubility of the test substance.

Quantification of the test substances occurs by comparison with calibration curves of the respective compound. The concentrations in the samples analysed must be bracketed by concentrations of standards. For test substances with a log P OW estimate higher than six a surrogate standard has to be spiked to the water sample prior to extraction in order to register losses occurring during extraction and pre-concentration of the water samples. For accurate recovery correction, the surrogates must have properties that are very close to, or identical with, those of the test substance.

Preferably, stable isotopically-labelled analogues of the substances of interest for example, perdeuterated or 13 C-labelled are used for this purpose. If the use of labelled stable isotopes, i. During liquid-liquid extraction of the water phase emulsions can form. They can be reduced by addition of salt and allowing the emulsion to settle overnight.

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Methods used for extracting and pre-concentrating the samples need to be reported. Samples withdrawn from the 1-octanol phase may, if necessary, be diluted with a suitable solvent prior to analysis. The details of the analytical method need to be reported. This includes the method of extraction, pre-concentration and dilution factors, instrument parameters, calibration routine, calibration range, analytical recovery of the test substance from water, addition of surrogate standards for recovery correction, blank values, detection limits and limits of quantification.

Performance of the Test. When choosing the water and 1-octanol volumes, the LOQ in 1-octanol and water, the pre-concentration factors applied to the water samples, the volumes sampled in 1-octanol and water, and the expected concentrations should be considered.

The experimental system should be protected from daylight by either performing the experiment in a dark room or by covering the reaction vessel with aluminium foil. The experiment should be performed in a dust-free as far as possible environment. The 1-octanol-water system is stirred until equilibrium is attained. In a pilot experiment the length of the equilibration period is assessed by performing a slow-stirring experiment and sampling water and 1-octanol periodically.

The sampling time points should be interspersed by a minimum period of five hours. Each P OW determination has to be performed employing at least three independent slow-stirring experiments. Determination of the equilibration time. The minimum equilibration time is one day before sampling can be started. As a rule of thumb, sampling of substances with a log P OW estimate of less than five can take place during days two and three.

The equilibration might have to be extended for more hydrophobic compounds. For a compound with log P OW of 8,23 decachlorobiphenyl hours were sufficient for equilibration. Equilibrium is assessed by means of repeated sampling of a single vessel. Starting the experiment. At the start of the experiment the reaction vessel is filled with 1-octanol-saturated water.

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Sufficient time should be allowed to reach the thermostated temperature. The desired amount of test substance dissolved in the required volume of 1-octanol saturated with water is carefully added to the reaction vessel. This is a crucial step in the experiment, since turbulent mixing of the two phases has to be avoided. To that end, the 1-octanol phase can be pipetted slowly against the wall of the experimental vessel, close to the water surface.

It will subsequently flow along the glass wall and form a film above the water phase. The decantation of 1-octanol directly into the flask should always be avoided; drops of 1-octanol should not be allowed to fall directly into the water. After starting the stirring, the stirring rate should be increased slowly. If the stirring motors cannot be appropriately adjusted the use of a transformer should be considered. It is a compromise between achieving a rapid rate of equilibration, while limiting the formation of 1-octanol micro-droplets.

Sampling and Sample Treatment. The stirrer should be turned off prior to sampling and the liquids should be allowed to stop moving. After sampling is completed, the stirrer is started again slowly, as described above, and then the stirring rate is increased gradually.

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The water phase is sampled from a stopcock at the bottom of the reaction vessel. The water in the taps is not stirred and therefore not in equilibrium with the bulk. Note the volume of the water samples, and make sure that the amount of test substance present in the discarded water is taken into account when setting up a mass balance.

Care should be taken not to disturb the boundary. The volume of the sampled liquid is recorded. A small aliquot is sufficient, since the 1-octanol sample will be diluted. Unnecessary sample transfer steps should be avoided. To that end the sample volume should be determined gravimetrically. In case of water samples this can be achieved by collecting the water sample in a separatory funnel that contains already the required volume of solvent.

According to the present Test Method, P OW is determined by performing three slow-stirring experiments three experimental units with the compound under investigation employing identical conditions. This allows for calculating variance as a measure of the uncertainty of the average value obtained by each experimental unit. The P OW can be characterized by the variance in the data obtained for each experimental unit. This information is employed to calculate the P OW as the weighted average of the results of the individual experimental units.

To do so, the inverse of the variance of the results of the experimental units is employed as weight. As a result, data with a large variation expressed as the variance and thus with lower reliability have less influence on the result than data with a low variance. Analogously, the weighted standard deviation is calculated.

It characterizes the repeatability of the P OW measurement. A low value of the weighted standard deviation indicates that the P OW determination was very repeatable within one laboratory. The formal statistical treatment of the data is outlined below. Treatment of the results. Demonstration of attainment of equilibrium. Achievement of chemical equilibrium is demonstrated by plotting this ratio against time. A plateau in this plot that is based on at least four consecutive time points indicates that equilibrium has been attained, and that the compound is truly dissolved in 1-octanol.

Log P OW -calculation. The weighted average is calculated by weighting the data with the inverse of the variance so that the influence of the data on the final result is inversely proportional to the uncertainty in the data. Average log P OW. The average value of log P OW of different experimental units is calculated as the average of the results of the individual experimental units weighted with their respective variances.

The reciprocal of the variance of log P OW,i is employed as w i. The weighted standard deviation can be computed from the weighted variance var log Pow,Av as follows:. Test substance:. Test conditions:. OECD Tolls J Boethling RS, Mackay D eds. Handbook of property estimation methods for chemicals.

bbmpay.veritrans.co.id/carrea-sitios-para-conocer-gente.php Environmental Organic Chemistry. Wiley, New York, NY. Aqueous speciation and 1-octanol-water partitioning of tributyl- and triphenyltin: effect of pH and ion composition. Chapter C. Lyman WJ Solubility in water. Leo A, Weininger D Medchem Software Manual. Houben-Weyl, ed, Methoden der Organischen Chemie : Spreadsheet for computation of minimum volumes of water required for detection of test substances of different log P OW values in aqueous phase.

In case of lower concentrations, larger volumes would be required. Estimation of S w. Estimation of S oct. Computation of volumes. Key to Computations. Overview of volumes required, as a function of water solubility and Log P ow. An example of glass-jacketed test vessel for the slow-stirring experiment for determination of P OW.

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The original acute inhalation Test Guideline TG was adopted in This revised Test Method B. Primary features of this Test Method are the ability to provide a concentration-response relationship ranging from non-lethal to lethal outcomes in order to derive a median lethal concentration LC 50 , non-lethal threshold concentration e.

LC01 , and slope, and to identify possible sex susceptibility. Definitions used in the context of this Test Method are provided at the end of this chapter and in GD 39 2. GD 39 2 provides guidance in the selection of the appropriate Test Method for acute testing. When information on classification and labelling only is required, chapter B. This Test Method B. Before considering testing in accordance with this Test Method all available information on the test chemical, including existing studies e. Information that may assist in the selection of the most appropriate species, strain, sex, mode of exposure and appropriate test concentrations include the identity, chemical structure, and physico-chemical properties of the test chemical; results of any in vitro or in vivo toxicity tests; anticipated uses and potential for human exposure; available Q SAR data and toxicological data on structurally related substances [see GD 39 2 ].

For specific regulatory needs e. These concentrations should be selected on a case-by-case basis and justification for concentration selection should be provided [see GD 39 2 ]. LC 50 , LC 01 and slope for one or both sexes as needed for quantitative risk assessments. This Test Method offers two methods. The first method is a traditional protocol in which groups of animals are exposed to a limit concentration limit test or a series of concentrations in a stepwise procedure for a predetermined duration of usually 4 hours.

Other durations of exposure may apply to serve specific regulatory purposes. Moribund animals or animals obviously in pain or showing signs of severe and enduring distress should be humanely killed and are considered in the interpretation of the test result in the same way as animals that died on test. Selection of animal species.

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Healthy young adult animals of commonly used laboratory strains should be used. The preferred species is the rat and justification should be provided if other species are used. Preparation of animals. Females should be nulliparous and non-pregnant. The animals are randomly selected and marked for individual identification.

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The animals are kept in their cages for at least 5 days prior to the start of the test to allow for acclimatisation to laboratory conditions. Animals should also be acclimatised to the test apparatus for a short period prior to testing, as this will lessen the stress caused by introduction to the new environment. Animal husbandry. Before and after exposures, animals generally should be caged in groups by sex and concentration, but the number of animals per cage should not interfere with clear observation of each animal and should minimise losses due to cannibalism and fighting.

When animals are to be exposed nose-only, it may be necessary for them to be acclimated to the restraining tubes. The restraining tubes should not impose undue physical, thermal, or immobilisation stress on the animals. If generic data are available to show that no such changes occur to any appreciable extent, then pre-adaptation to the restraining tubes is not necessary. Animals exposed whole-body to an aerosol should be housed individually during exposure to prevent them from filtering the test aerosol through the fur of their cage mates. Conventional and certified laboratory diets may be used, except during exposure, accompanied with an unlimited supply of municipal drinking water.

Inhalation chambers. The nature of the test chemical and the objective of the test should be considered when selecting an inhalation chamber.

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The preferred mode of exposure is nose-only which term includes head-only, nose-only or snout-only. Nose-only exposure is generally preferred for studies of liquid or solid aerosols and for vapours that may condense to form aerosols. Special objectives of the study may be better achieved by using a whole-body mode of exposure, but this should be justified in the study report.

Principles of the nose-only and whole body exposure techniques and their particular advantages and disadvantages are described in GD 39 2. Administration of concentrations. Nose-only exposures may be any duration up to 6 hours in rats. If mice are exposed nose-only, exposures generally should not exceed 4 hours. Justification should be provided if longer duration studies are needed [see GD 39 2 ].

Animals exposed to aerosols in whole-body chambers should be housed individually to prevent ingestion of test chemical due to grooming of cage mates. Feed should be withheld during the exposure period. Water may be provided throughout a whole-body exposure. Animals are exposed to the test chemical as a gas, vapour, aerosol, or a mixture thereof. Hygroscopic and chemically reactive test chemicals should be tested under dry air conditions.

Care should be taken to avoid generating explosive concentrations. Particle-size distribution. Particle sizing should be performed for all aerosols and for vapours that may condense to form aerosols. Although a reasonable effort should be made to meet this standard, expert judgment should be provided if it cannot be achieved. For example, metal fumes may be smaller than this standard, and charged particles, fibres, and hygroscopic materials which increase in size in the moist environment of the respiratory tract may exceed this standard. Test chemical preparation in a vehicle.

A vehicle may be used to generate an appropriate concentration and particle size of the test chemical in the atmosphere. As a rule, water should be given preference. Particulate material may be subjected to mechanical processes to achieve the required particle size distribution, however, care should be taken to not decompose or alter the test chemical. In cases where mechanical processes are believed to have altered test chemical composition e.

Adequate care should be taken to not contaminate the test chemical. It is not necessary to test non-friable granular materials which are purposefully formulated to be un-inhalable. An attrition test should be used to demonstrate that respirable particles are not produced when the granular material is handled. If an attrition test produces respirable substances, an inhalation toxicity test should be performed.

Control animals. A concurrent negative air control group is not necessary. When a vehicle other than water is used to assist in generating the test atmosphere, a vehicle control group should only be used when historical inhalation toxicity data are not available. If a toxicity study of a test chemical formulated in a vehicle reveals no toxicity, it follows that the vehicle is non-toxic at the concentration tested; thus, there is no need for a vehicle control.

Chamber airflow. The flow of air through the chamber should be carefully controlled, continuously monitored, and recorded at least hourly during each exposure. The monitoring of test atmosphere concentration or stability is an integral measurement of all dynamic parameters and provides an indirect means to control all relevant dynamic atmosphere generation parameters.

Special consideration should be given to avoiding re-breathing in nose-only chambers in cases where airflow through the exposure system are inadequate to provide dynamic flow of test chemical atmosphere. There are prescribed methodologies that can be used to demonstrate that re-breathing does not occur under the selected operation conditions 2 If there is reason to believe that these standards cannot be met, oxygen and carbon dioxide concentrations should be measured.

Chamber temperature and relative humidity. Test chemical: Nominal concentration. Whenever feasible, the nominal exposure chamber concentration should be calculated and recorded. The nominal concentration is the mass of generated test chemical divided by the total volume of air passed through the chamber system.

Test chemical: Actual concentration. Actual concentrations can be obtained by specific methods e. The use of gravimetric analysis is acceptable only for single component powder aerosols or aerosols of low volatility liquids and should be supported by appropriate pre-study test chemical-specific characterisations.

Multi-component powder aerosol concentration may also be determined by gravimetric analysis. However, this requires analytical data which demonstrate that the composition of airborne material is similar to the starting material. If this information is not available, a reanalysis of the test chemical ideally in its airborne state at regular intervals during the course of the study may be necessary. For aerosolised agents that may evaporate or sublimate, it should be shown that all phases were collected by the method chosen. The target, nominal, and actual concentrations should be provided in the study report, but only actual concentrations are used in statistical analyses to calculate lethal concentration values.

One lot of the test chemical should be used, if possible, and the test sample should be stored under conditions that maintain its purity, homogeneity, and stability. Prior to the start of the study, there should be a characterisation of the test chemical, including its purity and, if technically feasible, the identity, and quantities of identified contaminants and impurities. This can be demonstrated by, but is not limited to, the following data: retention time and relative peak area, molecular weight from mass spectroscopy or gas chromatography analyses, or other estimates.

When intermittent sampling is used, chamber atmosphere samples should be taken at least twice in a four hour study. If not feasible due to limited air flow rates or low concentrations, one sample may be collected over the entire exposure period. If marked sample-to-sample fluctuations occur, the next concentrations tested should use four samples per exposure.

Time to chamber equilibration t 95 should be calculated and recorded. The duration of an exposure spans the time that the test chemical is generated and this takes into account the times required to attain t Guidance for estimating t 95 can be found in GD 39 2. When the test chemical is a mixture, the analytical concentration should be reported for the mixture and not just for the active substance or the component analyte. Additional information regarding actual concentrations can be found in GD 39 2.

Test chemical: Particle size distribution. The particle size distribution of aerosols should be determined at least twice during each 4 hour exposure by using a cascade impactor or an alternative instrument such as an aerodynamic particle sizer. If equivalence of the results obtained by a cascade impactor or an alternative instrument can be shown, then the alternative instrument may be used throughout the study. The mass concentration obtained by particle size analysis should be within reasonable limits of the mass concentration obtained by filter analysis [see GD 39 2 ].

If equivalence can be demonstrated in the early phase of the study, then further confirmatory measurements may be omitted. For animal welfare reasons, measures should be taken to minimise inconclusive data which may lead to a need to repeat an exposure. Particle sizing should be performed for vapours if there is any possibility that vapour condensation may result in the formation of an aerosol, or if particles are detected in a vapour atmosphere with potential for mixed phases see paragraph If one sex is known to be more susceptible, the study director may choose to perform these studies using only the susceptible sex.

If rodent species other than rats are exposed nose-only, maximum exposure durations may be adjusted to minimise species-specific distress. Before commencing, all available data should be considered in order to minimise animal usage.

For example, data generated using chapter B. General considerations: Traditional protocol. In a Traditional study, groups of animals are exposed to a test chemical for a fixed period of time generally 4 hours in either a nose-only or whole-body exposure chamber. Animals are exposed to either a limit concentration limit test , or to at least three concentrations in a stepwise procedure main study.

A sighting study may precede a main study unless some information about the test chemical already exists, such as a previously performed B. Sighting study: Traditional protocol. A sighting study is used to estimate test chemical potency, identify sex differences in susceptibility, and assist in selecting exposure concentration levels for the main study or limit test.

When selecting concentration levels for the sighting study, all available information should be used including available Q SAR data and data for similar chemicals. A sighting study may consist of a single concentration, but more concentrations may be tested if necessary. A sighting study should not test so many animals and concentrations that it resembles a main study. A previously performed B.

Limit test: Traditional protocol. A limit test is used when the test chemical is known or expected to be virtually non-toxic, i. In a limit test, a single group of three males and three females is exposed to the test chemical at a limit concentration. Information about the toxicity of the test chemical can be gained from knowledge about similar tested chemicals, taking into consideration the identity and percentage of components known to be of toxicological significance. In those situations where there is little or no information about its toxicity, or the test chemical is expected to be toxic, the main test should be performed.

The selection of limit concentrations usually depends on regulatory requirements. It can be technically challenging to generate limit concentrations of some test chemicals, especially as vapours and aerosols. The limit concentration should only be considered when there is a strong likelihood that results of such a test would have direct relevance for protecting human health 3 , and justification provided in the study report.

In the case of potentially explosive test chemicals, care should be taken to avoid conditions favourable for an explosion. To avoid an unnecessary use of animals, a test run without animals should be conducted prior to the limit test to ensure that the chamber conditions for a limit test can be achieved. If mortality or moribundity is observed at the limit concentration, the results of the limit test can serve as a sighting study for further testing at other concentrations see main study.

If the limit concentration could not be attained, the study report should provide an explanation and supportive data. If the maximum attainable concentration of a vapour does not elicit toxicity, it may be necessary to generate the test chemical as a liquid aerosol. Main study: Traditional protocol. A main study is typically performed using five males and five females or 5 animals of the susceptible sex, if known per concentration level, with at least three concentration levels.

Sufficient concentration levels should be used to obtain a robust statistical analysis. The time interval between exposure groups is determined by the onset, duration, and severity of toxic signs. Exposure of animals at the next concentration level should be delayed until there is reasonable confidence of survival for previously tested animals. This allows the study director to adjust the target concentration for the next exposure group.

Due to the dependence on sophisticated technologies, this may not always be practical in inhalation studies, so the exposure of animals at the next concentration level should be based on previous experience and scientific judgement. GD 39 2 should be consulted when testing mixtures. This approach allows animals to be exposed to a test chemical at several concentration levels and for multiple time durations. All testing is performed in a nose-only chamber whole-body chambers are not practical for this protocol.

A flow diagram in Appendix 1 illustrates this protocol. Using 2 animals per sex per concentration and time point may reduce bias and variability of the estimates, increase the estimation success rate, and improve confidence interval coverage. However, in case of an insufficient close fit to the data for estimation when using one animal per sex or two animals of the more susceptible sex a 5th exposure concentration may also suffice.

A sighting study is used to estimate test chemical potency and to assist in selecting exposure concentration levels for the main study. It may be necessary to use three animals per sex to establish a sex difference. These animals should be exposed for a single duration, generally min. The feasibility of generating adequate test atmospheres should be assessed during technical pre-tests without animals. It is generally not necessary to perform a sighting study if mortality data are available from a B. When selecting the initial target concentration in a B.

The initial concentration Exposure Session I Appendix 1 will either be a limit concentration or a concentration selected by the study director based on the sighting study. When testing aerosols, the goal should be to achieve a respirable particle size i. This is possible with most test chemicals.

Testing in excess of the limit concentration should only be considered when there is a strong likelihood that results of such a test would have direct relevance for protecting human health 3 , justification should be provided in the study report. To avoid an unnecessary use of animals, a test run without animals should be conducted prior to testing at the initial concentration to ensure that the chamber conditions for this concentration can be achieved. If mortality or moribundity is observed at the initial concentration, the results at this concentration can serve as a starting point for further testing at other concentrations see main study.

The initial concentration Exposure Session I Appendix 1 tested in the main study will either be a limit concentration or a concentration selected by the study director based on the sighting study. Each subsequent exposure session will depend on the previous session see Appendix 1. For many test chemicals the results obtained at the initial concentration, together with three additional exposure sessions with a smaller time grid i. The animals should be clinically observed frequently during the exposure period.

Following exposure, clinical observations should be made at least twice on the day of exposure, or more frequently when indicated by the response of the animals to treatment, and at least once daily thereafter for a total of 14 days. The length of the observation period is not fixed, but should be determined by the nature and time of onset of clinical signs and length of the recovery period.

The times at which signs of toxicity appear and disappear are important, especially if there is a tendency for signs of toxicity to be delayed. All observations are systematically recorded with individual records being maintained for each animal. Care should be taken when conducting examinations for clinical signs of toxicity that initial poor appearance and transient respiratory changes, resulting from the exposure procedure, are not mistaken for test chemical-related toxicity that would require premature killing of the animals. The principles and criteria summarised in the Guidance Document on Humane Endpoints GD 19 should be taken into consideration 7.

When animals are killed for humane reasons or found dead, the time of death should be recorded as precisely as possible. In conclusion, Ti rods used longitudinally in a posterior spinal arthrodesis construct with an aggressive bend fail after a fewer number of cycles than CoCr rods. Europe PMC requires Javascript to function effectively.

Recent Activity. The snippet could not be located in the article text. This may be because the snippet appears in a figure legend, contains special characters or spans different sections of the article. Orthop Rev Pavia. Published online Mar PMID: Kalpit N. Shah , Gregory Walker , Sarath C.

Koruprolu , and Alan H. Contributed by Contributions: the authors contributed equally. Shah et al. Abstract Instrumentation failure is a common complication following complex spinal reconstruction and deformity correction. Key words: titanium, cobalt-chromium, posterior spinal fusion rods, pedical subtraction osteotomy, spinal deformity. Introduction Given the advances and options available for spinal implants, surgeons are better able to address spinal pathologies and deformities of increasing complexity.

Open in a separate window. Figure 1. Results An initial load-to-failure test of a Ti rod model required N for the rod to fracture. Figure 2. Figure 3. Example of a titanium model with a broken posterior titanium rod. Discussion and Conclusions The results of this study suggest that CoCr rods have a greater resistance to fatigue than Ti rods. Funding Statement Funding: none. References 1. Surgical Management of Spinal Deformities.

Elsevier Health Sciences; Apical sublaminar wires versus pedicle screws—which provides better results for surgical correction of adolescent idiopathic scoliosis? Spine Phila Pa ; 30 Comparative analysis of pedicle screw versus hook instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis. Spine Phila Pa ; 29 Improving safety in spinal deformity surgery: advances in navigation and neurologic monitoring. Eur Spine J ; 22 :S Coronal and sagittal plane correction in adolescent idiopathic scoliosis: a comparison between all pedicle screw versus hybrid thoracic hook lumbar screw constructs.

Spine Phila Pa ; 32 Wang MY. Improvement of sagittal balance and lumbar lordosis following less invasive adult spinal deformity surgery with expandable cages and percutaneous instrumentation. J Neurosurg Spine ; 18 Orthopedics ; 39 :e Outrigger rod technique for supplemental support of posterior spinal arthrodesis. Spine J ; 15 Adult spinal deformity surgery: complications and outcomes in patients over age Graham JJ. Complications of cervical spine surgery. Spine Phila Pa ; 14 Obesity and spine surgery: relation to perioperative complications.

J Neurosurg Spine ; 6 Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults. JAMA ; Complications in spine surgery. J Neurosurg Spine ; 13 Surgical treatment of traumatic fractures of the thoracic and lumbar spine: a systematic review of the literature on techniques, complications, and outcome.

Lumbar spine surgery in the elderly. Complications and surgical results. Spine Phila Pa ; 19 Other papers evaluate impact on results due to gauge length used in tests; mobility or constraint of the test blocks; and use of transverse rod connections. Spinal Device Components, Subassemblies, and Interconnections using ASTM F, this section discusses test methods for new components or modifications to existing components of a construct. Papers describe the impact from application of different transverse connector designs on clinical outcomes; and evaluate impact on bench testing results due to protection of the longitudinal member, anchoring materials, gauge length, mobility or constraint of the test blocks.

Interbody Spacers and Intervertebral Body Fusion Devices provides the latest developments and results associated with the application of ASTM F test methods for intervertebral body fusion devices.