Cleanliness Validation For Medical Devices

By Chris Pickles, Ph.D.

Residues on the surface of medical devices can cause implant failure and poor device performance. The main source of these residues is from materials used in the manufacture of the device, although contamination during the storage, cleaning and handling of the device is also known to occur. Small amounts of these surface residues can cause deleterious effects in patients, because the residues are in direct contact with body tissues and patients often have compromised immune systems (Beal, 2009). In addition, residues may often alter the surface chemistry and geometry of the device, so even inert residues can be a problem. For example, small amounts of non-toxic cutting fluid on an implant limit the ability of surrounding tissues to attach to the implant (Jackson and Ahmed, 2007).

In order to minimise contamination, the Federal Drug Administration (FDA) stipulates that medical device manufacturers follow specific cleanliness validation procedures (FDA, 2003). Firstly, they must identify all possible residues present on the device and set an acceptable residue limit (Luginbuehl et al, 2006). Then, they must use a cleaning regime that reduces residue levels below this limit, without leaving significant levels of cleaning agent behind. Finally documentation to verify that residue limits are not exceeded must be submitted to the FDA before the device can go on the market (Luginbuehl et al, 2006).

Despite these procedures being in place, some medical devices are failing to meet FDA requirements for cleanliness verification and validation. Since 2001, 173 medical devices have been recalled, some due to contamination issues (Medical Device Recalls, 2009). In just one year of sterility inspections, more than 483 FDA observations related to validation deficiencies - more than any other deficiency (Booth, 1999).