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PubMed2000

Women, men, and contraceptive sterilization.

OBJECTIVE: To review the social and behavior contexts of decisions about contraceptive sterilization and to analyze factors associated with sterilization choices. DESIGN: Multinomial logit regression of sterilization. PATIENT(S): Various subsamples as appropriate to specific analyses drawn from the 10,847 women interviewed in the 1995 National Survey of Family Growth, and the 5,227 men interviewed in the National Survey of Families and Households. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Tubal sterilization and vasectomy. RESULT(S): Surprisingly high proportions of recent tubal sterilizations were performed on unmarried women: 1 in 3 overall, 1 in 5 among white non-Hispanic women, and 2 in 3 among black women. Sterilization choice among continuously married couples also revealed large differences by race and ethnicity. Parity at the time of the last wanted birth is a major factor affecting sterilization choices, although significant effects were found as well as for a number of other variables, including age differences between spouses, education, and religion. Compared with other regions, the ratio of tubal sterilizations to vasectomies is extremely low in the Western region of the United States. CONCLUSION(S): Analysis of sterilization decisions must be based on time since the completion of childbearing. The findings call attention to the need for measuring variables that mediate observed associations with sterilization outcomes.

Adolescent↗
PubMed1997

Effects of various chemical sterilization methods on the crosslinking and enzymatic degradation characteristics of an epoxy-fixed biological tissue.

Due to the nature of bioprostheses, which are mainly biological tissues that cannot be sterilized with heat or irradiation, the sterilization method by choice is generally liquid chemicals. It is known that a number of liquid chemicals can have rapid germicidal effect and can be used to sterilize bioprostheses. The study was to evaluate the effects of various chemical sterilization methods on the crosslinking and enzymatic degradation characteristics of an epoxy-fixed biological tissue. The chemical sterilants employed were: a 70% ethanol solution (EtOH), a 2% epoxy compound + 20% ethanol solution (EX-810), a 2% propylene oxide + 20% ethanol solution (PO), and a 0.625% glutaraldehyde + 20% ethanol + 0.2% polysorbate solution (GA). Both masking and crosslinking of the free amino groups within the epoxy-fixed tissue were observed subsequent to sterilization with GA or EX-810. This improved the resistance of the GA or EX-810 sterilized tissues against collagenase degradation as compared to its nonsterilized counterpart. However, subsequent to sterilization with PO, only masking of the free amino groups within the epoxy-fixed tissue was noted. The inhibition of the collagenase degradation by masking of the free amino groups was traded off by the more random molecular packing of the PO sterilized sample due to the introduction of the side branches. Sterilization of the epoxy-fixed tissue with EtOH may increase its denaturation temperature and tensile strength, while neither masking nor crosslinking of free amino groups within the tissue took place. The resistance to degradation of the EtOH sterilized tissue, however, did not improve as compared to its nonsterilized counterpart.

Bioprosthesis↗
PubMed1999

Antigenicity of cortical bone allografts in dogs and effect of ethylene oxide-sterilization.

The aims of the present study were to determine the antigenicity of cortical bone allografts and the effect of ethylene oxide-sterilization (EO-sterilization). Cortical bone allografts from one donor dog were implanted in a muscle pouch in four groups of four dogs each. The grafts were either fresh, EO-sterilized, demineralized or demineralized and EO-sterilized. The immune response against the grafts was determined by measuring the antibody response against surface antigens of donor cells and by the mixed lymphocyte reaction. Dogs receiving EO-sterilized grafts or bone matrix did not demonstrate an immune response. Only two of the four dogs with fresh cortical bone grafts showed a very weak immune response. This suggests a priming of the host by the fresh bone grafts. However, implanting skin grafts from the donor dog subdermally, in one dog of each of the groups, four months after implanting the bone grafts did not induce a secondary immune response. Macroscopic and histologic examination of the bone grafts five months after their implantation consistently revealed graft resorption (activity of osteoclasts) and vascularization of the fresh bone grafts, but not of EO-sterilized fresh grafts. For most EO-sterilized grafts, a strong inflammatory reaction was present in the tissues surrounding the graft and this was not apparent around the non-sterilized grafts. The absence of resorption and the presence of the inflammation seemed to be unwanted effects of the EO-sterilization. The EO-sterilisation did not affect osteoinduction since osteocytes were observed in the EO-sterilized demineralized grafts. Results indicate that cortical bone allografts used in the present study are very weak antigens and that the EO-sterilization procedure used has no effect on osteoinduction, but decreases bone resorption.

Animals↗
PubMed2001

Sterilization and disinfection in general practice within university health services.

A postal questionnaire on 'sterilization and disinfection' was sent to all 144 nurse members of the British Association of Health Services in Higher Education (BAHSHE). Forty-nine (34%) completed valid questionnaires were returned. Despite the majority of practices performing minor surgical procedures such as cervical cytology (N= 40, 82%), ear syringing (N= 44, 90%) and wound dressing (N= 49, 100%), only 11 (22%) had access to a sterile supply department (SSD), and the definitions of sterilization and disinfection were only identified by 23 (52%) and 14 (32%) of the respondents, respectively. Forty-one (84%) respondents had a benchtop sterilizer (30 had a benchtop sterilizer, 11 a vacuum sterilizer and two had both), although there was considerable confusion on their appropriate use and maintenance. Just over half had written procedures for sterilizer use, no practice changed the sterilizer water on a daily basis as recommended by the Medical Devices Agency (MDA), few kept a sterilizer logbook and even fewer had read the MDA Device Bulletin on benchtop sterilizers. The majority of respondents voiced an interest in attending a workshop on sterilization and disinfection. We conclude that despite the location of the general practices within an academic environment, the concept of infection control is clearly not understood by university health service staff. As the implications of a failure to implement proper infection control procedures are potentially serious, the need for adequate education and training of staff is of critical importance.

Clinical Competence↗
PubMed1993

Evaluation of a rapid readout biological indicator for flash sterilization with three biological indicators and three chemical indicators.

OBJECTIVE: Flash sterilization is most commonly used for emergency sterilization of unwrapped items in a gravity displacement sterilizer for three minutes. Sterilization quality assurance is monitored by biological indicators that require a 24-hour incubation prior to reading. In this study, we compared a new biological indicator that provides results within 60 minutes with three conventional, 24-hour biological indicators for monitoring flash sterilization and three chemical indicators. DESIGN: Conventional biological indicators tested included the conventional Attest 1261, Proof Flash and Assert, while the rapid readout indicator tested was Attest 1291. Attest Rapid Readout detects the presence of a Bacillus stearothermophilus enzyme by reading a fluorescent product that is produced by the enzymatic break-down of a nonfluorescent substrate. Chemical indicators tested included Comply, Incheque, and Thermalog S. Survival at 132 degrees C in a gravity displacement sterilizer was measured by media color change after incubation for 24 hours at 56 degrees C for the three conventional biological indicators, fluorescence at 60 minutes for the Attest Rapid Readout biological indicator, and color change for the chemical indicators. Each exposure time was replicated four times with 10 of each biological and chemical indicator per run. RESULTS: The conventional biological indicators (Attest, Proof Flash, and Assert) had 90%, 48%, and 40% spore survival at two minutes exposure; 23%, 3%, and 0% at three minutes exposure; and 3%, 0%, and 0% at four minutes exposure respectively. The Attest Rapid Readout biological indicator had 88%, 33%, and 0% enzyme activity detectable at 2, 3, and 4 minutes exposure. The chemical indicators Comply, Incheque, and Thermalog S revealed sterilization failure rates of 100%, 100%, and 100% at 0 minutes exposure; 100%, 100%, and 45% at one minute; 0%, 0%, and 28% at two minutes exposure; 0%, 0%, and 18% at three minutes exposure; and 0%, 0%, and 0% at four minutes exposure, respectively. CONCLUSION: The sensitivity of the Attest Rapid Readout parallels the conventional biological indicators. These data suggest that a 60-minute rapid readout biological indicator is equivalent to the 24-hour biological indicators. If further studies demonstrate that a four-minute flash sterilization cycle provides a needed safety margin to ensure sterilization, then consideration should be given to requiring a four-minute flash sterilization cycle. Chemical indicators were too sensitive to the processing conditions (eg, steam) and are inadequate to ensure adequate sterilization.

Evaluation Studies as Topic↗
PubMed1993

[Measurement of ethylene oxide at a medical sterilization site].

Although ethylene oxide gas is widely used as a sterilizing agent for medical instruments because of its disinfection property, the effects of its use in medical settings have not been clarified. In the present study, we measured the ethylene oxide gas concentration (EOGC) within a hospital sterilization unit and in the ambient air near the unit. Before the sterilizer was turned on (about 9:00), the ambient air EOGC was below the detection limit (0.1 ppm). When the door was opened to place the instruments in the sterilizer, the maximum EOGC near the door of the sterilizer was 1.71 ppm. Before the sterilizer door was opened, the residual EOGC within the sterilizer was 0.10-24.56 ppm. During the operation of the sterilizer (9:00-17:00), ethylene oxide gas could not be detected in the air near the unit. When the sterilizer door was opened at the end of the routine operation of the sterilizer (about 17:00), EOGC near the door was 2.10-2.73 ppm. After the door was closed, the ambient air EOGC level was 0.5-0.57 ppm. These findings indicate that the personnel near the unit were exposed to ethylene oxide gas for about 15 min during the transfer. However, no ethylene gas could be detected by the ethylene oxide gas monitor (3M Co., #3551). The finding that EOGC in sterilized medical instruments after 24 h of aeration was about 2 ppm also suggests that the personnel using these instruments were exposed to ethylene oxide gas.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed2003

Effect of terminal sterilization with gas plasma or gamma radiation on wear of polyethylene liners.

BACKGROUND: Although terminal sterilization with gamma radiation in air promotes cross-linking, which improves wear resistance, it also results in free radicals, which can oxidize and degrade the mechanical properties of polyethylene liners used for total hip arthroplasty. For this reason, non-cross-linked polyethylene components have also been sterilized with chemical surface treatments, such as gas plasma. In this study, we tested the hypothesis that conventional polyethylene liners cross-linked by sterilization with gamma radiation in air had better in vivo wear performance than non-cross-linked liners sterilized with gas plasma. METHODS: We retrospectively reviewed the wear rates in a series of hips treated with a Duraloc 100 cup, a 28-mm femoral head, and an Enduron liner that had been sterilized with either gamma radiation (sixty-one hips followed for a mean of 5.2 years) or gas plasma (sixty-three hips followed for a mean of 3.9 years). The irradiated liners had been stored with access to ambient oxygen for an average of 1.0 year (range, 0.05 to 5.72 years) prior to implantation. Multiple linear regression was used to assess the effect of the sterilization method on the wear rate while accounting for the possible influence of other factors, including liner geometry, femoral head material, patient gender, cup abduction angle, and age at surgery. RESULTS: The polyethylene liners that had been sterilized with gamma radiation in air had a significantly lower wear rate than did the gas-plasma-sterilized liners (0.097 compared with 0.19 mm/yr, p < 0.001). The sterilization method (p < 0.001) and age at surgery (p = 0.001) were the only factors that we analyzed that correlated with the wear rate. CONCLUSIONS: The in vivo wear of conventional polyethylene liners that had been sterilized with gamma radiation in air was, on the average, 50% less than that of non-cross-linked liners sterilized with gas plasma. LEVEL OF EVIDENCE: Therapeutic study, Level III-2 (retrospective cohort study). See Instructions to Authors for a complete description of levels of evidence.

Gamma Rays↗
PubMed2006

Comparison of hydrogen peroxide and peracetic acid as isolator sterilization agents in a hospital pharmacy.

PURPOSE: The efficacy of hydrogen peroxide and peracetic acid as isolator sterilization agents was compared. METHODS: Sterilization and efficacy tests were conducted in a flexible 0.8-m3 transfer isolator using a standard load of glass bottles and sterile medical devices in their packing paper. Bacillus stearothermophilus spores were placed in six critical locations of the isolator and incubated at 55 degrees C in a culture medium for 14 days. Sterilization by 4.25 mL/m3 of 33% vapor-phase hydrogen peroxide and 12.5 mL/m3 of 3.5% peracetic acid was tested in triplicate. Sterility was validated for hydrogen peroxide and peracetic acid at 60, 90, 120, and 180 minutes and at 90, 120, 150, 180, 210, and 240 minutes, respectively. RESULTS: In an efficacy test conducted with an empty isolator, the sterilization time required to destroy B. stearothermophilus spores was 90 minutes for both sterilants, indicating that they have comparable bactericidal properties. During the validation test with a standard load, the sterilization time using hydrogen peroxide was 150 minutes versus 120 minutes with peracetic acid. The glove cuff was particularly difficult for hydrogen peroxide to sterilize, likely due to its slower diffusion time than that of peracetic acid. Hydrogen peroxide is an environmentally safer agent than peracetic acid; however, its bacteriostatic properties, lack of odor, and poor diffusion time may limit its use in sterilizing some materials. CONCLUSION: Hydrogen peroxide is a useful alternative to peracetic acid for isolator sterilization in a hospital pharmacy or parenteral nutrition preparation unit.

Disinfectants↗
PubMed1998

Determining the capability of a drug product to be terminally sterilized: a case study involving a heat-sensitive, oxygen-sensitive drug product.

A decision scheme for determining the capability of a finished product dosage form to be terminally sterilized was presented and followed for a heat-sensitive, oxygen-sensitive drug product (DP). Studies were conducted first in a laboratory steam sterilizer and then in a production unit. When a nonheat-sensitive steam sterilization cycle produced unfavorable loss of potency and increases in the amount of impurities, a new heat-sensitive steam sterilization cycle was investigated. An acceptable product was produced by reducing the headspace oxygen level and reducing the heat delivered to the product during terminal sterilization. The amount of sterilizing steam heat delivered to the product was reduced by reducing the allowable temperature range from set-point of the terminal steam sterilizer, and by developing a new heat-sensitive cycle. The heat-sensitive cycle, with a model based upon a known relationship of the biological indicator, product D value, and the environmental bioburden, can achieve a 10(-6) sterility assurance level when it delivers an F0 > or = 4 min. When the standard terminal sterilization model and cycle produced unacceptable levels of degradation, formulation/production changes, and terminal sterilization model and cycle modifications were explored, before the DP was directed to aseptic filling. Acceptable moist heat terminal sterilization the DP was then achieved.

Drug Stability↗
PubMed2000

[Oxidation of ultra high molecular weight polyethylene as a result of sterilization].

PURPOSE OF THE STUDY: To improve (UHMWPE) Ultra High Molecular Weight Polyethylene quality for use in arthroplastic components, sterilization related oxidative changes were investigated in raw and manufactured material. MATERIAL: To evaluate sterilization related effects, 15 x 15 mm samples of UHMWPE were taken from a defined area of raw manufactured UHMWPE plates. The raw manufactured plates were produced using the compression molding method. For sterilization, gamma irradiation with and without air, ETO-sterilization and autoclave sterilization were performed. METHODS: Infrared spectroscopy was used to detect oxidation damage of the implant in superficial and deep layers of the material. RESULTS: Gamma sterilization on air showed 40% more oxidation compared with air-free sterilization. The superficial oxidation on air was 0.33 and showed the lowest value without air on argon with 0.155. Using ethylenoxide sterilization, no great changes in superficial oxidation (0.229) were observed; the smallest change (0.07) was observed at a depth of 2.79 mm. Autoclave sterilization caused the greatest superficial oxidation with 0.622 but low oxidation at 0.094 mm depth. In all samples, further oxidation and ongoing crystallinity was seen with increasing storage time. CONCLUSION: Ethylenoxide sterilization should be recommended for UHMWPE since oxidative changes is lowest. Gamma sterilization can only be recommended without air and at low doses.

Joint Prosthesis↗
PubMedDate not supplied

Sterilization of a small caliber vascular graft with a polyexpoxy compound.

Sterilization of tissue based medical devices via cold sterilization processes has been limited to formaldehyde, glutaraldehyde, and mixtures of the same with alcohols and surfactants. The authors report the sterilization of a small caliber vascular graft with a combination of diglycidyl ether and ethanol. The sterilant contains 1-4% diglycidyl ether and 10-20% ethanol as an aqueous solution. Sterilization is achieved after exposure of the graft to the sterilant solution for a period of 7 days at an elevated temperature (30 degrees - 40 degrees C). The biologic indicator selected for efficacy studies was Bacillus subtilis niger ATCC 9372 (endospores). The grafts were inoculated with a concentrated endospore suspension and immersed in the sterilant solution for increasing time periods. After extensive rinsing over membrane filters to remove any residual sterilant, the grafts and filters were cultured in tryptic soy broth. D10 values were calculated using a fraction-negative, most probable number technique. Additionally, many representative bacteria and fungi were tested and found to be susceptible to the new sterilant developed. The diglycidyl ether/alcohol sterilant developed was found to be efficacious for sterilization of the tissue based vascular grafts tested.

Bacteria↗
PubMed2001

Effects of handling and storage on sterile dental instruments.

The microbial contamination post-sterilization of dental instruments has been the object of permanent study. The aim of the present study was to evaluate factors affecting long-term sterility of dental instruments sterilized in the dry-oven or autoclave at the Central Sterilizing Service of the School of Dentistry, University of Buenos Aires stored under room temperature and humidity conditions. Half of the 192 samples were placed in standard closed metal containers and sterilized in a dry-oven (D.O), and the remaining half were placed in perforated metal containers and sterilized in an autoclave (A). All the samples were placed in sterilizing paper bags for medical use. Post sterilization, each group (DO and A) was divided into: Group I: minimal handling (control); Group II: wrapping torn mechanically (1 cm); Group III: wrapping torn manually (1 cm). All the samples were stored a closed cabinet. Contamination was evaluated at 30 and 180 days, by seeding under aerobic and anaerobic conditions. Temperature was monitored throughout the experiment, and ranged between 20 degrees C and 31 degrees C (x: 24 degrees C +/- 3.9). Humidity was measured with a digital hygrometer, and ranged between 40% and 60% (x: 54% +/- 10). Group I evidenced no microbial contamination, unlike Groups II and III. Our results evidence that 1) dry oven or autoclave sterilized material that is handled properly during storage remains sterile regardless of variations in temperature and humidity; 2) improper handling affects sterility, and contamination is time-dependent.

Alloys↗
PubMed2005

[Is gestagen IUD a realistic alternative to female sterilization?].

INTRODUCTION: For years, female sterilization has been regarded as the most reliable contraceptive method available. However, sterilization is irreversible and requires a surgical procedure. The purpose of our investigation was to see how many women who were offered a reversible, long-term, non-surgical method would prefer it as an alternative to sterilization. MATERIALS AND METHODS: All women referred to our unit for sterilization in the years 2000 and 2001 were offered a consultation in non-operative methods of long-term contraception. All women were offered a levonorgestrel intrauterine system (LNG-IUS) while waiting to be sterilized. The women who chose LNG-IUS were followed for 1-3 years to see if they were later sterilized. RESULTS: Of the 151 women, 14 didn't come in for consultation. Among the 137 remaining women, the primary choice for 69 (50%) was sterilization; 58 women (43%) chose LNG-IUS, and 10 (7%) chose other alternatives. By the end of the observation period, 6 (10%) of the 58 women in the LNG-IUS group had chosen to be sterilized. DISCUSSION: LNG-IUS is a long-term reversible contraceptive method with an efficacy comparable to that of female sterilization. The results suggest that all women referred for sterilization should be counselled about effective alternative methods before proceeding with sterilization.

Adult↗
PubMed2005

[Comparison between the efficacies of two different methods of preparing Esmarch bandages for sterilization].

OBJECTIVES: Sterile Esmarch bandages have a widespread use in orthopedic surgery. We evaluated the efficacy of two different methods of preparing Esmarch bandages for sterilization. METHODS: Two groups of Esmarch bandages were used, each group consisting of 25 bandages. The size of the bandages was 6.3 cm in width and 450 cm in length. Before sterilization, the bandages were tightly rolled in one group and loosely folded at a length of 10 cm in the other. An indicator was inserted at every five layers of all bandages. Sterilization was evaluated by subjecting both groups to ethylene oxide cycles and the autoclave method. A standard orthopedic surgical set was used as a control during each sterilization. RESULTS: Following sterilization with ethylene oxide, all the indicators were found sterile in both groups. Similarly, complete sterilization was obtained in the loosely folded bandages with the autoclave method. However, only the indicators placed in the first 15 layers and the fiftieth layer were fully sterile in the tightly rolled bandages after autoclaving. The number of sterile indicators in the remaining layers ranged from nine (36%) to 23 (92%). CONCLUSION: Ethylene oxide is a reliable technique for sterilizing Esmarch bandages. The bandages must be loosely folded, instead of tightly rolling, when the autoclave technique is used.

Bandages↗
PubMed1991

Sterilization. Disciplined microbial control.

The goal of instrument processing is to protect patients by preventing cross-contamination from instruments. The processing involves a series of sequential steps aimed at removing and killing microbes on contaminated instruments and maintaining those instruments in an aseptic state until they are reused. These steps must be conducted carefully to assure success and to reduce chances of disease spread or physical injury to those handling the contaminated instruments. Presoaking begins the cleaning process and facilitates terminal cleaning by ultrasonic or manual scrubbing. If instruments are not properly cleaned, subsequent sterilization may be jeopardized by insulation of blood- or saliva-coated microbes from the sterilizing agent. Items that would be destroyed by heat should be cleaned and sterilized in a properly prepared glutaraldehyde solution. Cleaned instruments must be packaged prior to heat sterilization to protect them from recontamination after sterilization and before reuse. Sterilization of cleaned, packaged instruments in steam, chemical vapor, or dry heat sterilizers must involve proper loading, processing, drying, and cooling. Routine use of spore tests and chemical indicators will provide quality assessment of packaging procedures and operation of the sterilizer, as well as assist in identifying processed packages during distribution. Using the results of sterilization monitoring to adjust procedures as a means of assuring sterilization provides quality assurance to the office staff and to the patients that the instruments have been properly processed. Carefully handling storage and distribution of the sterilized instrument packs or trays reduces the chances for recontamination until the instruments are reused. Instrument processing is a major part of the office infection control program. It must be performed in a controlled manner with proper monitoring to achieve the desired outcome of patient protection.

Dental Instruments↗
PubMed1982

Ethylene oxide sterilization of medical devices--with special reference to the sporicidal activity and residual concentration of ethylene oxide and its secondary products.

For the sterilization of disposable medical devices, ethylene oxide gas is used in most cases. When this sterilization method is used, ethylene oxide (EO) and its secondary products, i.e., ethylene chlorohydrin (ECH) and ethylene glycol (EG), remain in the medical devices after sterilization. If their concentration is high, these residues are liable to cause hemolytic activity and dermal or mucous membrane irritability in the human body. For this reason, in 1978 the FDA announced a proposal to regulate the residual limits of EO, ECH and EG. Our studies were done to examine the conditions of EO sterilization from the viewpoints of the sterilization effect and the residual chemical substances and to find the optimum conditions for sterilization. Further, the aerator was fabricated for the exclusive purpose of reducing, within a brief period, the concentration of EO and other substances remaining in the medical devices after sterilization and we examined the condition of aeration by using this aerator. As the result, it was found that a satisfactory sterilization effect could be obtained under the sterilization conditions of an EO gas concentration of 500 mg/liter, a sterilizing temperature of 55 to 60 degrees C and a sterilizing time of two hours, and under these conditions the concentration of the residual substances such as the EO could be made comparatively lower. It was also clarified that the minimum required aeration conditions by using the exclusive-use aerator were a temperature of 55 to 60 degrees C and an aeration time of 24 hours and over.

Equipment and Supplies↗
PubMed1993

[Sterilization--the microbiology between claim and reality].

Sterilization means to free an object from all living and viable germs. To fulfill this claim, the microbiology is confronted with some fundamental problems. Under the action of a microbicidal agent the microorganisms do not die at the same time, even if there is a homogeneous population. The destruction of microorganisms follows a special destruction order. The number of dying organisms is always proportional to the number of viable organisms present. On theoretical grounds it is, therefore, impossible to free an object from all living and viable germs; there will ever be left a certain proportion of viable germs, even if this proportion may be very small. The aim of sterilization must be to keep that proportion very small. To reach this goal in a practical time without damaging the objects to be sterilized, microorganisms of high resistance should be excluded, i.e. the objects to be sterilized should not be contaminated by microorganisms of high resistance to the sterilizing agent(s). The assurance level that an object is free from all living and viable germs must be so high that it is practically impossible to proof this by a test for sterility. On the other hand, the absence of microorganisms of high resistance in the objects to be sterilized makes it feasible to use microorganisms of high resistance as test organisms for the manufacture of microbiologic indicators. Such indicators enable to record as an integral the action of all microbicidal parameters of the noxious agent(s) far beyond the region for which the application of a test for sterility is sensible. Nevertheless, bioindicators have a similar status as the physical and physico-chemical controlling instruments. Microbiological indicators make it possible to guarantee the application of a certain (minimal) efficacy of the microbicidal agent(s). Whether this efficacy is sufficient to reach the wanted sterility assurance level depends, last not least, on the microbiological contamination (bioburden) of the object to be sterilized. Each sterilization process has its own prerequisites.

Anti-Bacterial Agents↗
PubMed1996

Overview of polyethylene as a bearing material: comparison of sterilization methods.

Polyethylene has been used for more than 30 years as an orthopaedic bearing material; however, there has been recent concern regarding the early failure of a small percentage of the polyethylene bearings. The damage seen in some retrieved polyethylene components has been linked to gamma radiation sterilization in air, which was widely used by the industry for years. Gamma radiation in air has been documented to cause an increase in oxidation and degradation of mechanical properties with time. The degradation of polyethylene initiated by gamma sterilization in air has led the orthopaedic industry toward alternative sterilization methods, including gamma radiation in an inert gas or vacuum environment, ethylene oxide gas sterilization, and gas plasma sterilization. For many of these alternative techniques, little clinical performance data exist. This study is a comparative evaluation of sterilization methods using the same analytic techniques that have been used to document the effects of gamma sterilization in air on polyethylene. Fourier transform infrared spectroscopy, electron spin resonance, and uniaxial tensile testing are used to compare, respectively, the oxidation levels, free radical concentration, and mechanical properties of material sterilized by each method. The polyethylene is evaluated before sterilization, poststerilization, and postartificial aging. All examined alternative sterilization methods, when compared with gamma sterilization in air, caused less material degradation during a component's preimplantation shelf life.

Electron Spin Resonance Spectroscopy↗