Control of methyl methacrylate during the preparation of orthopedic bone cements

Occupational hazards and pregnancy in orthopaedics: female surgeons are at increased risk of infertility and pregnancy complications

Female surgeons have increased rates of infertility and pregnancy complications compared to the general population. Reported infertility rates in surgeons are 32% compared to 10.9% in the general population. Reported pregnancy complication rates in surgeons range from 25% to 35%. In the orthopaedic operating theatre occupational hazards that have an effect on pregnancy outcomes include radiation, exposure to methyl methacrylate in bone cement, surgical smoke, sharps injuries, exposure to anaesthetic waste gases and the effects of the physical demands of surgery including prolonged work hours and night shift work. Outside the operating theatre exposure to nitrous oxide, formaldehyde, surgical scrub also have evidence of negative pregnancy outcomes. This review summarizes the available evidence as it relates to specific occupational hazards that face health workers in an orthopaedic operating theatre. This information, while targeted at orthopaedic health workers, is also relevant to anaesthetists, radiographers, nursing staff, medical device company representatives and female surgeons in other specialties.

A portable negative pressure unit reduces bone cement fumes in a simulated operating room

In this report, we demonstrate a versatile method for the removal of bone cement fumes from the vicinity of health care workers in a simulated operating room. The mixing of two component bone cement in the perimeter of an operating room releases volatile organic compounds (VOCs). The use of localized negative pressure within proximity of the mixing vessel is expected to reduce the concentration of VOCs dispersed near the airway of operating room personnel. A standard two component bone cement formulation was mixed in the perimeter of a simulated operating room. A median VOC concentration of 19 ppm was detected with a portable VOC detector. When a portable negative pressure unit was stationed near the mixing area at distances of 8 and 36 cm from the mixing vessel, the median VOC rise was reduced by approximately 97% and 83%, respectively, relative to the control. The use of a portable negative pressure unit provides a potential increase in the safety for all staff when working with materials that give off VOCs in the operating room.

Methyl methacrylate and respiratory sensitisation: a comprehensive review

Methyl methacrylate (MMA) is classified under GHS as a weak skin sensitiser and a skin and respiratory irritant. It has recently been proposed that MMA be classified as a respiratory sensitiser (a designation that in a regulatory context embraces both true respiratory allergens, as well as chemicals that cause asthma through non-immunological mechanisms). This proposal was based primarily upon the interpretation of human data. This review, and a detailed weight of evidence analysis, has led to another interpretation of these data. The conclusion drawn is that persuasive evidence consistent with the designation of MMA as a respiratory sensitiser is lacking. It is suggested that one reason for different interpretations of these data is that occupational asthma poses several challenges with respect to establishing causation. Among these is that it is difficult to distinguish between allergic asthma, non-allergic asthma, and work-related exacerbation of pre-existing asthma. Moreover, there is a lack of methods for the identification of true chemical respiratory allergens. The characterisation and causation of occupational asthma is consequently largely dependent upon interpretation of human data of various types. Recommendations are made that are designed to improve the utility and interpretation of human data for establishing causation in occupational asthma.

Bone cement usage modalities at a multi-site university hospital centre

BACKGROUND

Although cements are widely used during arthroplasty procedures, few recommendations exist regarding their optimal usage modalities, which, nevertheless, govern the long-term surgical outcomes. No detailed information is available on how cements are used in French hospitals. The objectives of this questionnaire survey among surgeons working at a multi-site university hospital in France were to describe practices, determine whether these varied with surgeon experience, and look for differences compared to recommendations.

HYPOTHESIS

Cementing techniques vary widely among surgeons at a university hospital.

MATERIAL AND METHODS

A questionnaire was sent to the five orthopaedic departments of our university hospital to collect data on the surgeons (age, sex, years of experience), their practice (type of implants used, annual number of arthroplasties with each arthroplasty type and each indication, and proportion of cemented arthroplasties), the type of cement used, and the cementing technique.

RESULTS

Of the 34 surgeons, 21 completed the questionnaire, 20 males and 1 female with a mean age of 41 years (range, 31-59 years) and a mean of 11 years (range, 1-29 years) of experience. High-viscosity antibiotic-loaded cement was preferred by 20 (95%) surgeons, notably for knee arthroplasties, of which the median annual numbers were 55 (range, 0-218) and 8 (range, 1-40) for primary and revision cemented procedures, respectively. Various cementing techniques in ambient air were used: 12/21 (57%) surgeons used pulsed lavage to prepare the bone before cementation and 18/21 (86%) applied the cement to both the bone cuts and the implant. Of the 18 surgeons who performed knee arthroplasties, 12 used pulsed lavage, including 9 of the 11 surgeons with more than 5 years of experience and only 3 of the 7 less experienced surgeons. Similarly, of the 12 surgeons who used pulsed lavage for cemented arthroplasties, 11 were among the 12 surgeons who performed more than 15 cemented arthroplasties annually and 1 was among the 6 who performed fewer cemented arthroplasties.

DISCUSSION

Cementing techniques varied widely, reflecting the dearth of recommendations and controversial results of published studies. In our centre, the use of pulsed lavage to improve bone preparation and cement application to both the bone and the implant should be promoted, as both techniques are universally advocated. Our study demonstrates the need to provide surgeons with opportunities to exchange their experiences about the other aspects of cementing in order to harmonise practices and to optimise the use of cement.

LEVEL OF EVIDENCE

IV, questionnaire survey.

Airborne Exposure of Methyl Methacrylate During Simulated Total Hip Arthroplasty and Fabrication of Antibiotic Beads

As the use of cement remains prevalent in orthopedic surgery, so do concerns over the safety of its active ingredient, methyl methacrylate (MMA). The Occupational Health and Safety Agency (OSHA) limits the airborne exposure to 100 parts per million (ppm) averaged over an 8 hour period. We measured MMA exposure to operating room personnel during simulated total hip arthroplasty (THA), antibiotic bead fabrication and simulated spill of MMA. Cumulative and peak exposures during simulated THA and antibiotic bead fabrication did not exceed OSHA limits of 100ppm. Vacuum mixing and greater distance from the vapor source reduced measured MMA exposure. Spilled MMA led to prolonged and elevated MMA levels. MMA levels returned to a negligible level in all scenarios by 20 minutes after mixing.

Methyl methacrylate levels in orthopedic surgery: comparison of two conventional vacuum mixing systems

Poly-methyl methacrylate bone cements contain methyl methacrylate (MMA), which is known for its sensitizing and toxic properties. Therefore, in most European countries and in the USA, guidelines or regulations exist for occupational exposures. The use of vacuum mixing systems can significantly reduce airborne MMA concentrations during bone setting. Our goal was to test two commonly used vacuum mixing systems (Palamix(®) and Optivac(®)) using Palacos(®) R bone cement for their effectiveness at preventing MMA vapor release in a series of standardized trials in a laboratory as well as in an operating theatre. MMA was quantified every second over a period of 3 min using a photoionization detector (MiniRAE(®) 3000) device positioned in the breathing area of the user. Significant differences in MMA mean vapor concentrations over 180 s were observed in the two experimental spaces, with the highest mean concentrations (7.61 and 7.98 ppm for Palamix(®) and Optivac(®), respectively) observed in a laboratory with nine air changes per hour and the lowest average concentrations (1.06 and 1.12 ppm for Palamix(®) and Optivac(®), respectively) in an operating theatre with laminar flow ventilation and 22 air changes per hour. No significant differences in overall MMA concentrations were found between the two vacuum mixing systems in either location. Though, differences were found between both systems during single mixing phases. Thus, typical handling of MMA in orthopedic procedures must be seen as not harmful as concentrations do not reach the short-term exposure limit of 100 ppm. Additionally, laminar airflow seems to have an influence on lowering MMA concentrations in operation theatres.

Inhalation study of polymethyl methacrylate following radiologist exposure during percutaneous vertebroplasty

OBJECTIVE

To assess the atmospheric concentrations of methyl methacrylate (MMA) vapors during percutaneous vertebroplasty for the interventional radiologist and the other operating room staff.

MATERIALS AND METHODS

During percutaneous vertebroplasty, a polymethyl methacrylate (PMMA) mixture (about 20 mL) was prepared with a mixing system in a normally ventilated room. Atmospheric concentrations of MMA vapors were measured by a gas absorbent badge for individual exposure (GABIE) passive sampler attached to the surgical gowns of the interventional radiologist and the other operating room staff over a period of 460 min. Active sampling was performed over 15 min with an individual pump placed near the breathing zone of the radiologist. MMA vapor concentrations were then measured using gas chromatography and activated charcoal tubes.

RESULTS

Mean MMA vapor concentrations measured by the GABIEs over the period of 460 min were 0.51 parts per million (ppm) for the radiologist and 0.22 ppm for the other operating room staff. The emission peaks measured by using charcoal tubes over 15 min were 3.7 ppm.

CONCLUSION

MMA vapor concentrations during percutaneous vertebroplasty were well below the recommended maximum exposure of 100 ppm over the course of an 8-h workday.

Methyl methacrylate and respiratory sensitization: a critical review

Methyl methacrylate (MMA) is a respiratory irritant and dermal sensitizer that has been associated with occupational asthma in a small number of case reports. Those reports have raised concern that it might be a respiratory sensitizer. To better understand that possibility, we reviewed the in silico, in chemico, in vitro, and in vivo toxicology literature, and also epidemiologic and occupational medicine reports related to the respiratory effects of MMA. Numerous in silico and in chemico studies indicate that MMA is unlikely to be a respiratory sensitizer. The few in vitro studies suggest that MMA has generally weak effects. In vivo studies have documented contact skin sensitization, nonspecific cytotoxicity, and weakly positive responses on local lymph node assay; guinea pig and mouse inhalation sensitization tests have not been performed. Cohort and cross-sectional worker studies reported irritation of eyes, nose, and upper respiratory tract associated with short-term peaks exposures, but little evidence for respiratory sensitization or asthma. Nineteen case reports described asthma, laryngitis, or hypersensitivity pneumonitis in MMA-exposed workers; however, exposures were either not well described or involved mixtures containing more reactive respiratory sensitizers and irritants. The weight of evidence, both experimental and observational, argues that MMA is not a respiratory sensitizer.