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Effective cleaning processes ensure orthopedic devices meet quality and safety standards before they enter the operating room, and validating those processes confirms that cleaning methods remove manufacturing contaminants, a key part of gaining regulatory approval before product commercialization.
It’s a straightforward process in theory, but oversights do happen. A review of best practices is always warranted, especially as orthopedic devices and manufacturing projects grow in complexity.
Organized From the Start
Matthew Homuth, Senior Validation Engineer at Cretex Medical | QTS, said cleaning processes should be designed based on manufacturing and device design commonalities.
When organizing devices for cleaning purposes, Homuth advised grouping devices under cleaning families instead of product families. According to ISO 19227:2018, a cleaning family is “a set of implants, cleaned with the same or an equivalent process being less critical or comparably critical with respect to the cleanliness specification of the worst-case specimen(s) and the risks to be in a contaminated state when the cleaning process has been completed as that of the worst-case specimen(s).”
Homuth said grouping devices according to common manufacturing processes is also helpful. “A cleaning family should share the same or very similar manufacturing sequences, including contact materials,” he added. “By doing so, the challenge to the cleaning process is normalized and the potential for outliers is greatly reduced.”
Cleaning risk associated with a device is driven by its intended use. Homuth pointed out that implantable devices require higher scrutiny compared to surgical instruments due to contact modality and duration. When defining a cleaning family, he said the acceptable residue limit should be based on the device with the highest clinical risk.
During cleaning validation, Homuth suggests choosing a device that represents a group of worst-case components based on device characteristics and manufacturing processes. Representative devices should have these worst-case device attributes:
- Surface Area. The largest device in a cleaning family typically has the most potential to carry the highest residue load.
- Challenging features like deep blind holes, threading and cannulations where fluid exchange is restricted will impact cleaning.
- Surface Finish. Rougher surfaces or porous coatings trap more residues than smooth surfaces, which can impact cleaning capability.
- Hydroxyapatite and antimicrobials require careful consideration during cleaning process development. These materials can interact with the cleaning agents and impact the intended use of the device. As a result, the worst-case device might need to be challenged before the coating is added. The extraction process used during testing should also be evaluated to ensure there is no interference from the coating.
It’s also important to identify which manufacturing process within the cleaning family could result in the largest preclean residues. “Finishing processes like anodizing and electropolishing inherently remove all manufacturing contact materials and strip a small layer of the base material, which effectively resets the residue profile,” Homuth said.
He added that the most complex manufacturing process does not always present the most risk to the cleaning process, and the worst-case device might not include all manufacturing processes.
When a cleaning family is proposed, there may not be a device that contains all challenge features in the family. In these cases, consider using a simulated device that includes all challenge features and worst-case manufacturing processes in the cleaning family.
“The simulated device should be of equal or greater challenge to the process than any of the components in the cleaning family,” Homuth said. “Remember, omission of some manufacturing processes — anodizing and electropolishing — should be considered to maximize the potential residue load.”
Any simulated device must be thoroughly vetted before use. Justification should firmly demonstrate how the simulation represents all risks associated with the capability of the cleaning process. Regulators will scrutinize the rationale for using simulated products, so associated rationale should be well documented and understandable, Homuth warned.
All device attributes — such as blind holes, small lumens, surface textures, knurling and tight threads, internal corners — should be considered during the design for manufacturing phase. Homuth said the manufacturing sequence is a major factor in assessing cleaning capability and feasibility, and he identified some factors to consider:
- It may not be feasible to consistently clean (or clean at all) a device that consists of assembled components. A component permanently fixed within another component or press fit mated surfaces present inherent challenges.
- Mechanical agitation during cleaning can impact assemblies. For example, set screws may loosen or even be removed under ultrasonic agitation.
- Coatings may need to be applied after the final cleaning process. In these cases, the coating process needs to be performed in a controlled environment to prevent contamination. Also, testing may be needed on the uncoated and coated device if a partial coating is used.
Keep in mind that detergents must reach all surfaces of a device and rinse agents need to reach the detergents. Detergents have low surface tension, so allow for adequate space to ensure the effectiveness of the cleaning and rinsing process.
Striving for Standardization
The same process does not always equal the same result when it comes to cleaning validations. “Orthopedic company reps sometimes believe that when an existing cleaning process on an existing cleaning machine is copied to a new machine, the validations are correct,” said Wesley Gensch, a MedTech Global Key Account Manager at Ecoclean. “Often, that’s not the case.”
Most cleaning failures are caused by variables that weren’t written into the SOP, according to Gensch.
“An SOP is a dashboard. It records time, temperature, chemistry and cycle,” he said. “But what actually drives proper cleaning lives in cavitation distribution, bath aging, water quality, loading geometry and operator habits. None of that shows up in the SOP, so you can transfer a validation flawlessly on paper and still fail in production.”
The features that are hardest to clean on a device — blind holes, lumens, internal channels — are usually addressed last during validation tests. “If your validation only succeeds when everything is perfect, you’ve validated your laboratory, not your manufacturing process,” Gensch said.
According to Gensch, approaches to cleaning validation and documentation differ widely among OEMs. Many organizations establish their own terminology, documentation structures and validation methodologies, creating consistency within their in-house operations but increasing complexity when expanding manufacturing networks or adopting new cleaning technologies.
He works with OEM customers to develop a standardized cleaning validation process. His first request is to connect with their cleaning operators, who often provide invaluable insights into what works with cleaning processes, and just as importantly, what doesn’t.
Difficulties often emerge when OEMs seek to harmonize cleaning procedures across multiple facilities or apply validation assumptions developed around legacy testing methods to newer technologies and more sophisticated measurement tools. Rather than simply duplicating existing validation models, engineers should assess whether modern measurement techniques provide a more representative picture of actual cleaning performance.
User Requirement Specifications (URS) play an important role by defining the functional requirements of a cleaning system. However, Gensch noted that these documents frequently focus on what the equipment must accomplish while providing less detail on how those requirements will be verified and validated.
As a result, disconnects can occur that make it difficult to transfer otherwise robust cleaning processes between machines, facilities or operating environments. To reduce these risks, some OEMs are incorporating validation activities into factory acceptance testing (FAT) and site acceptance testing (SAT). The goal is to ensure that cleaning equipment qualifications are documented, tested and delivered as part of the implementation process. Those tests must be clearly communicated to cleaning systems suppliers, Gensch noted.
“Know your FAT and SAT protocols and understand how we can implement installation qualification and operational qualification processes to set up our cleaning validation,” he said.
