Sterilizing and disinfection are not the same as cleaning. A device may be sterile. A sterile device may be left in an airtight container and remain sterile for years, perhaps decades. However, if the device is not clean, it can still negatively impact the host.
There are a number of potential negative impacts of non-viable residue on the host. For one thing, the host is not sterile, so oils and other contaminants on the device can provide “food” for host bacteria. Contaminants can interact with the host immune system and can interfere with device interaction with the host; for example, contaminants can interfere with osseointegration. Leachable contaminant residue can be toxic to the host.
In addition to minimizing viable contamination on medical devices, it is crucial to develop, define, validate, and control the cleaning process. There are many sources of contamination, viable and non-viable. Because assembly activities, process chemistries, and process materials inevitably contribute to contamination, it is important to physically remove undesirable surface material, whether or not that material is alive, dead, or has never been viable. Soil is matter out of place; cleaning is removal of matter out of place. With sterilizing or disinfecting, the issue is rendering the contaminant non-viable. With cleaning, the issue is physically removing contaminants from the surface without changing that surface in a way that interferes with product performance.
For practical purposes, critical cleaning includes removing soil and achieving the appropriate level of cleanliness (absolute cleanliness is not likely to happen), surface quality, and surface characteristics. The term industrial cleaning is often used to imply less exacting cleaning activities. However, there is a continuum of cleaning from initial fabrication to final assembly of the device. Because an inappropriate industrial cleaning process can result in adherent residues or surface damage, defining and controlling initial industrial cleaning is crucial for device quality assurance.