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 still harbour contaminants
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.”
Recent research from Aakash Agarwal and colleagues concurs with Burns, citing multiple issues with conventional reprocessing. Foremost among these is the increased rate of surgical infection. The incidence of surgical site infections in spine surgery is reported in the medical literature as up to 13%. Writing in a separate study also published in the Global Spine Journal, Aakash Agarwal et al write: “Surgical infection is undoubtedly a multifactorial phenomenon with implant handling and clean delivery being only one of these factors [influencing infection rates].” An increased infection rate necessitates longer hospital stays, and may mean that patients are required to undergo reoperations. In addition to the financial and logistical issues this causes, spending a longer time in hospital places an emotional burden on patients. The financial burden of surgical site infections is huge. According to the literature, the average hospitalisation cost for a surgical site infection resulting from orthopaedic surgery is estimated to be US$62,000 per case, at an average frequency of 5.5% of cases.
Speaking to Spinal News International, Aakash Agarwal (Department of Bioengineering and Orthopaedic Surgery, Engineering Center for Orthopaedic Research Excellence, University of Toledo, Toledo, USA), first author on four studies published this year investigating the impact of contamination of reprocessed pedicle screws, explains, “In the first phase, i.e. preoperative contamination, the pedicles screws undergo repeated bulk-cleaning with dirty instruments from the operating room, leading to residue build up at the interfaces and possibly on the surfaces too. This, due to its concealed nature, remains unnoticed by the Sterile Processing Department or other hospital staff.”
However, Aakash Agarwal goes on to note, “These can be avoided by using single-use pre-sterilised screws, which are becoming popular these days, with many countries issuing a ban towards repeated implant reprocessing.”
The second source of contamination is intraoperatively. This may occur, according to Agarwal, if “the sterile pedicle screw shafts are directly touched by the scrub technician with soiled gloves for loading onto an insertion device/screw driver, and is then kept exposed on the working table (either separately or next to the used instruments as the pedicles hole are being prepared).”
In order to avoid this contamination, Aakash Agarwal and colleagues recommend shielding the pedicle screws intraoperatively using a guard. Plastic surgeons and general surgeons have adopted a practice of using an additional layer of barrier against contamination of the implants (Keller’s funnel and wound edge protectors, respectively), and the study investigators suggest it is time for spinal surgeons to follow suit.
Aakash Agarwal argues that this two-step asepsis, involving pre-packaged and pre-sterilised screws, and then a shield, is critical: “Shielding the pedicle screws intraoperatively using a guard provides a superior level of asepsis than currently practiced. All unshielded pedicle screws were carrying bioburden of virulent bacterial species, which provides an opportunity for the development of postoperative infections.”
Many patients undergoing spinal surgery are immune-compromised, and the depth of the screw-bone interface in fusion renders the surgical site fairly inaccessible. Thus, as noted above, it is essential that bacterial contamination is minimised. Pre-sterilised, pre-packaged pedicle screws are still vulnerable to contamination once inside the operating room: during loading, they are touched by technicians, then they are exposed while lying on the tray and while the other pedicle screws are being loaded. Finally, the pedicle screws are touched by the surgeon when being fit checked.
In a study performed by Agarwal and colleagues, 25 pre-sterilised, pre-packaged pedicle screws without a guard were compared to the same number of pre-sterilised, pre-packaged pedicle screws with a guard at four different surgical centres. Following spectroscopy and streaking, it was revealed that there was bacterial contamination in 100% of the unguarded pedicle screws, and a complete absence of contamination in the guarded pedicle screws. In the unguarded screws, which had been preoperatively sterilised in exactly the same way as the guarded screws, 105–107 colony forming units were counted per screw (See image below). The species were identified as Staphylococcus Epidermidis, S. Aureus, S. Pettenkoferi, and Micrococcus Luteus.
Another recent study, by Lukas Leitner (Department of Orthopedics and Trauma, Medical University of Graz, Austria) and colleagues, published in the European Spine Journal, reports that pedicle screw loosening is correlated to chronic subclinical deep implant infection. The investigators conclude: “Chronic implant infection seems to play a role in pedicle screw loosening and ongoing pain, causing revision surgery after spinal fusion. Screw loosening and multiple prior spinal operations should be [grounds for suspicion] suspicious (sic) for implant infection after spinal fusion when it comes to revision surgery.”
While many experts believe the severity of bacterial contamination is underreported, and the ramifications—both in terms of cost and patient safety—are extensive, Agarwal is not alone in calling for a two-step asepsis process to reduce or eliminate bacterial infection at the surgical site.
It should be noted that Aakash Agarwal is director of research and development for Spinal Balance, a company providing sterile and proprietary no-touch orthopaedic implants; Anand Agarwal holds a stock option in Spinal Balance.
My dad had zimmer screws put in, and he developed infection and is right now admitted in the hospital. I was upset and angry, and asked the doc about this. He told me that even if he had put in the other screw (I believe Medtronics) that they are currently using in the hospital, it is still washed again and again in the hospital. I am surprised why isn’t this standard.
Sorry to hear that. Postop infection is debilitating, especially at old age. Wish him speedy recovery.
In my practice we have been using post op vancomycin but the rate of infection hasn’t reduced. We are putting together a manuscript on that.
I was unaware of this method up till now. I will reach out to my Globus and see if they can provide me this capability. I already knew that nothing good comes from exposing the implants but it was industry standard which I cannot change unless I present evidences of such. Now we do have them. Great work.
Hi Rajat. To introduce myself: I am the Editor of Spinal News International, and the author of this article—nice to ‘meet’ you, and thank you for engaging with the story. Would you be able to get in touch regarding a follow-up piece. I would like to discuss a potential pitch with you. My email is [email protected]. Thank you!
Very interesting article. May I ask what is meant by the word guarded? Is it covered with a sterile drape or something different?
Hi Paula. The guard mentioned in this specific context is a sheath; the Libra sheath by Spinal Balance
Very good article. Many other medical studies are too complicated or left open to interpretation for me to understand (even though i am a gastroenterology nurse by profession) but this seems so instinctive that i am really surprised they aren’t already doing it.
I saw this article at the minimally invasive society meeting, LV. It said “reprocessed pedicle screws” vs “pre-sterilised, pre-packaged pedicle screws”, I must still have a copy on my desk.
But now I see the bacterial image footer and it mentions that both were “pre-sterilised, pre-packaged pedicle screws” and difference is “without guard” and “with guard”. Could you clarify which is what?
Hi Olivia, the online version of this article is the correct one. The print version was in error: the difference in bacterial presence shown on the front page of the paper, and here in the article, is actually between unguarded pre-sterilised, pre-packaged pedicle screws and guarded pre-sterilised, pre-packaged pedicle screws. Hope that helps.
Also could you share the link or directory to all the studies mentioned in your article?
It would help me make a report for my manager, if he would want me to explore this further.
Links now added to the story
Infection is horrible. My mom passed away due to this after back surgery. They removed the screws and put new ones but her body wasn’t strong enough to take it 😔.
Doctors said they did all by the book, and gave her more than normal dose of antibiotics! 😡
I will pass this discovery along to my friends and family in Facebook and twitter. This needs to change NOW! 💪
Thank you Suzie for writing with such clarity!
In the world of information overload, many necessary measures fall through the crack. I hope your viewers (practicing spine surgeons, industrial medical device providers, policy makers) and most importantly the public won’t let this slip by.
You were the first media personnel
who caught these evidences and brought it to a broader audience. I am grateful and I know the entire community will be too.
I never understood before why biofilm grows between pedicle and screw threads, as that site isn’t exposed like the rest of the superficial surgical site. Now I completely understand. It is concerning, as we transmit it there ourselves. And a lot of clinical evidences now are available capturing the bacterial dose and SSI rates. Also in hindsight, common sense!
Ingenious! A physical cover vs expensive antibiotics
Both reducing deep infections:
I choose Cover!
How to get this in Turkey?
I have been considering surgery past 6 months now and it seems like all standard screws carries a substantial amount of infection risk. The other option my spine specialist gave me was a device (coflex) that goes inbetween the two spine bones but doesn’t penetrate deep inside the bone like screws. He also mentioned that the surgery is safer than inserting screws.
Coflex is not a universal substitute, and pedicle-screws are necessary for most cases and pathologies.
Regarding the hygiene problem with these screws, it is due to the logistics and handling. The industry and regulatory body should take care of it.
We are also insisting, I asked the Medtronics rep recently about this, but the initiatives has to come from them. Besides the invisible bacteria, i see visible bone or tissue particles stuck in the central channel of the screws every now and then.
You as a physician cannot be serious about it, that is just sad. Seeing it in your theatre and not doing a thing. And you expect businessmen and politician who are not medical doctor to do that for you then there is no hope left in the system.
States- the most expensive healthcare system in the world. This article proves higher cost doesn’t always equate higher quality.
#broken healthcare system