14th September 2018
Contaminated pedicle screws cost hundreds of thousands of US dollars a year, and through an increase in surgical site infections result in additional and avoidable patient morbidity. Anand Agarwal (University of Toledo, Toledo, USA) and colleagues are calling for a change in the standard of care revolving around implant handling and delivery, cutting costs and improving patient safety.
Less widely recognised is the fact that contamination of pedicle screws still occurs in the sterile field, with intraoperative bacterial contamination needing an urgent solution.
So the issue of contamination is two-fold: outside of the operating room, concerning the reprocessing of pedicle screws, and inside the operating room, when pedicle screws are left exposed on trays and are infected with several common bacterial strains.
Reprocessed pedicle screws have been shown to still have residual microbial and non-microbial contaminants on them. In a study conducted by Aakash Agarwal (Department of Bioengineering and Orthopaedic Surgery, Engineering Center for Orthopaedic Research Excellence, University of Toledo, Toledo, USA) and colleagues, published in the Global Spine Journal, traces of saccharides (including biofilm, endotoxins and fatty tissue), soap residue, and salt residue were identified on six pedicle screws randomly selected from four different trays of cleaned, wrapped and purportedly sterilised implants. In fact, there is evidence that the amount of carbohydrate residue increases following reprocessing. The investigators also found corrosion stains present on the outer surface of the implants.
The screws were retrieved using clean gloves, and immediately placed inside of clean zip-lock polybags before undergoing optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and Fourier transform infrared spectroscopy.
That reprocessed pedicle screws are not always fully sterile has already influenced policy decisions in some nations. Japan and Scotland have banned the reprocessing of spinal implants used for spinal surgery. The Scottish Health Department said in a statement that repeatedly reprocessing implants in the hospital “is a suboptimal procedure”, following a letter in 2006 from the then chief medical officer for Scotland, Harry Burns.
Burns wrote: “Most orthopaedic units in NHS Scotland use screws, small plates and other small orthopaedic implants which have been repeatedly reprocessed (cleaned and sterilised) by the local Central Decontamination Unit in racks or trays. Concerns have been raised that these implants cannot be properly cleaned, and we have photomicroscopic evidence that they retain or acquire organic and/or chemical residues during reprocessing. Legally, many of these devices are classified as ‘single use’, which means they must not be re-used following contact with a patient, but also that they should only be cleaned and sterilised once, prior to first use. We suspect many of these devices have been recirculating for many years, some perhaps for over two decades. Besides generic concerns over infection and CJD [Creutzfeldt-Jakob Disease] contamination, there is evidence to suggest that reprocessed steel implants can cause inflammatory reactions to a much greater degree than ‘pristine’ devices as delivered by the manufacturer, and there are also issues of corrosion and weakening caused by repeated processing. This has clear implications for reducing implant failures, and we have no option but to address the legal, regulatory and governance issues this practice raises.”