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Lead times for ethylene oxide (EtO) sterilization remain long, and backlogs remain high. For orthopedic companies without sufficient financial runway, these delays can become a significant barrier to new product commercialization.
The capacity challenges remain an ongoing concern for the industry, even as the deadline for medical device sterilization facilities to comply with EtO emission limitations imposed by the Environmental Protection Agency was extended to April 2028. Although EtO will continue to have its place in device sterilization, orthopedic companies must continue to explore effective alternative methods.
Radiation Represents the Future
From a process-capability standpoint, sterilization modalities are classified as photon-based systems (gamma and x-ray) versus electron-based systems (e-beam).
“Even within these categories, not all radiation beams behave the same,” said Rose LaRue-Slater, Director of Sales at SteriTek. “Photons have no mass or charge, which allows for deep penetration into materials. E-beam consists of charged particles, and penetration depth is energy-dependent. The higher the electron energy, the deeper the dose penetration.”
LaRue-Slater acknowledged that gamma is often perceived as the most effective option due to the number of sterilization facilities in which it’s used. She added that e-beam and x-ray are often viewed as advantageous because they are electrically generated. Still, each comes with trade-offs: e-beam requires careful consideration of product presentation and orientation to ensure dose uniformity, while x-ray systems are highly energy inefficient, which impacts operating cost and throughput.
There are also broader considerations to keep in mind. Unlike gamma, e-beam and x-ray don’t rely on mined radioactive sources from geopolitically sensitive regions such as the Democratic Republic of Congo, Venezuela and Russia. Gamma sources also decay over time, resulting in approximately 1.3% monthly capacity loss, and require ongoing transport and replenishment of radioactive material.
Claims that e-beam isn’t suitable for orthopedic devices are not totally accurate, and x-ray is not inherently superior to gamma, according to LaRue-Slater.
“Each technology has a purpose, and all are playing a role in safe healthcare,” she said. “The point is to make sure we have reliable methods of sterilization available. There’s only one supplier of radioactive cobalt in the world for gamma sterilization. It’s important to have another option.”
According to LaRue-Slater, gamma delivers a relatively lower dose rate and greater material effects due to greater time to oxidize and exposure to ozone. E-beam has the highest dose rate, therefore the lowest material effects due to the lowest time to oxidize and least exposure to ozone. X-ray’s variable dose rates depend on the system’s power.
In practice, modality selection is highly dependent on the application. LaRue-Slater said e-beam is well-suited for low-density or individually packaged products and less appropriate for thick devices or parts that are packaged in big, dense boxes. However, she noted, e-beam might still be applicable in these cases if the packaging configuration is changed.
X-ray can process any product suitable for gamma or e-beam, but its lower energy efficiency makes it most practical for full-pallet processing, where throughput can be maximized.
In terms of orthopedic applications, e-beam provides value in polymer crosslinking processes, smaller packaged components such as screws and fixation devices, and for certain gamma-sensitive polymer systems.
There are still e-beam-related limitations that companies must design around, primarily related to penetration depth.
High-density products, such as large implants, present challenges for uniform dose delivery. In contrast, x-ray sterilization is a compelling option because of its technical capabilities and practical considerations, such as increased global capacity and reduced dependence on traditional EtO providers.
Additionally, many new x-ray systems are being designed as pallet irradiators, eliminating the need for depalletizing and repalletizing, which improves sterilization efficiency.
For companies currently using gamma sterilization, evaluating a switch to e-beam or x-ray is straightforward, according to LaRue-Slater. “If a validated gamma dose already exists, the first step is typically to pass a dose audit in the new modality, followed by completion of a dose mapping study to confirm performance.”
Safe and Effective Gas Sterilization
Clordisys has developed a proprietary water-soluble chlorine dioxide technology that does not dissociate in the sterilization chamber, meaning it can penetrate virtually any space, including tiny cracks, crevices and small lumens.
Chlorine dioxide is non-carcinogenic, non-flammable and non-explosive. “That’s particularly important when sterilizing devices with embedded batteries, where many alternative modalities, often oxidizers, can present safety challenges,” said Emily Lorcheim, Vice President of Sterilization Technologies at Clordisys. “Chlorine dioxide is one of the gentlest oxidizing mechanisms available, making it compatible with most materials.”
The gas can also process cellulose-based materials, including packaging such as cardboard, unit cartons, instructions for use, and most other paper-based components.
Lorcheim referenced a study that found that chlorine dioxide is 1,075 times more potent than EtO under equivalent processing conditions, which addresses skepticism about whether chlorine dioxide can match EtO’s effectiveness.
The gas also has a molecular size of approximately 0.124 nanometers, allowing it to penetrate a device’s small features and fine surface imperfections.
“One of the key differentiators compared to ethylene oxide is the aeration phase,” Lorcheim said. “Aeration occurs within the sterilization chamber and is typically completed in about 30 minutes, significantly shorter than traditional ethylene oxide cycles.”
Additionally, the entire process operates at ambient temperature. There is no need to elevate temperature to achieve sterilization lethality.
Cycle times range from four to eight hours, depending on the application. The process also offers flexibility in pressure levels. For complex packaging or hard-to-reach areas in a device, a vacuum can be applied to enhance penetration. Alternatively, cycles can be run at ambient pressure when required by the product or packaging configuration.
Chlorine dioxide also has a high safety profile, particularly through its use in food and water applications. Lorcheim pointed out that organic fruit treated with chlorine dioxide can still be classified as organic and noted that it’s also widely used to treat public water systems. From a chemical standpoint, chlorine dioxide breaks down into chlorite and chloride, which are benign salts.
Lorcheim referenced a case study that evaluated chlorite and chloride levels on a device following sterilization with chlorine dioxide. No detectable levels of the minerals were found, supporting the effectiveness of the process in leaving minimal residuals.
Chlorine dioxide is significantly gentler than many other oxidizing sterilants based on how the gas is generated. Clordisys utilizes a 2% chlorine gas cylinder within its proprietary cartridge system to produce a form of the sterilant at greater than 99% purity, without chlorine breakthrough or the formation of acidic byproducts. This high level of purity contributes to chlorine dioxide’s material compatibility.
Not all chlorine dioxide systems are the same. Much of the variation in material compatibility is caused by differences in additives, coatings or processing aids within product materials. It’s therefore important to test the exact make-up of the materials you’re sterilizing.
Chlorine dioxide is like EtO in that it is a true gas sterilant that is compatible with cellulosic materials. It can be used in multi-pallet chamber systems and is capable of sterilizing complex devices and large volumes.
“However, there are also important differences,” Lorcheim said. “Chlorine dioxide is non-carcinogenic, non-explosive and operates with faster cycles with zero emissions. Residuals are non-detectable and safe, and sterilization systems can also be brought in-house if needed.”
It’s just one more option for orthopedic companies that continue to look for ways to limit EtO sterilization before the government forces their hand.
Editor’s notes:
Secure your spot at OMTEC 2026 to attend Rose LaRue-Slater’s in-booth presentation about the future of radiation sterilization in orthopedics.
Watch Clordisys’ on-demand webinar to learn more about the company’s chlorine dioxide sterilization technology.
