Pedicle screws harbor microbial and non-microbial contaminants due to repeated reprocessing and intraoperative exposure, which are then transplanted deep in the bone and can lead to infection.
Aakash Agarwal, PhD, is the director of research and development at Spinal Balance, an adjunct professor at the University of Toledo (Ohio), and the lead author of Global Spine Journal studies on pedicle screw infection control. He recently spoke with Becker's Spine Review about the implications of his team's research for spine surgery practice.
In one study published in Global Spine Journal, researchers randomly selected six "sterile" pedicle screws that underwent repeated reprocessing and sterilization, which they assessed using optical microscopy. Study authors identified three types of contaminants: corrosion, saccharides of unknown origin and soap residue.
A single-center study published in Global Spine Journal, a multi-center study presented at the North American Spine Society 2018 Annual Meeting in Los Angeles, Sept. 26-29, and a multi-center study presented at the Society for Minimally Invasive Spine Surgery 2018 forum in Las Vegas, Sept. 6-8, assessed the bacterial growth on pedicle screws in the sterile field during live surgeries. They found all unshielded pedicle screws harbored virulent bacterial species. When an intraoperative pedicle screw guard was used, however, no such bacterial growth occurred.
Previous researchers also agree that both repeated reprocessing and sterilization as well as intraoperative handling seem to lead to contamination of sterilized implants, according to a study published in Global Spine Journal . Researchers conclude that using a terminally sterilized device may mitigate repeated reprocessing and sterilization. But only the use of fresh sterile gloves for handling each implant and/or a permanent shielding technique could potentially avoid recontamination at the operating theater.
Question: What are the biggest study takeaways for spine surgeons?
Dr. Aakash Agarwal: Our research work provides a consistently reliable and effortless method with no compliance required by hospital or operating room staff and surgeon to provide 'quantified' safety and savings to the community.
The studies also strongly corroborate and complements our colleagues' discoveries, such as:
- A high correlation of screw loosening with the presence of bacterial growth in the interfacing tissue (Leitner et al 2018) ,
- Reduced surgical site infection rates when changing gloves before handling screws (Rehman et al 2015)
- Reduced SSI rates when disinfecting pedicle screws in an antibiotics bath intraoperatively (Eren et al 2018)
Q: How should spine surgeons advocate for pedicle screw led infection control?
AA: This question was also raised earlier at the NASS 2018 solution showcase presented by Dean Steve Garfin, and panel discussions led by Neel Anand, MD, and Michael Stauff, MD. Spine surgeons can now reasonably demand their respective implant provider or industry representative to provide:
1. Prepackaged pre-sterile single use pedicle screws.
2. A mechanism to keep the pedicle screw sterile during surgery while the scrub tech is loading them onto the insertion device, waiting fully-exposed besides other instruments and when a surgeon checks the fit of the screw just before implantation. The mechanism shouldn't depend on glove change or disinfecting implants using antibiotics, because they add the issue of compliance, extra steps and supposedly cost to the operating room.
Also, due to the availability of extensive set of evidences over multiple independent research teams, it deserves a spot in NASS advocacy guidelines. No one, including patients, surgeons, hospital, industry, insurance companies or policy makers, benefits from not complying with this. The best part of this 'evidence-based practice' is there are no side effects or exclusion criteria.