Are Your Sterile Implants Really Sterile?

Two-Part Solution

The problem with pedicle screw contamination is twofold—first, contamination through reprocessing and second, contamination in the operating room, i.e., inside ‘sterile’ field.

The problem of contamination through reprocessing can be solved by using single-use, pre-sterilized screws. To combat the issue of intraoperative pedicle screw contamination, Agarwal and colleagues developed the method of intraoperative implant prophylaxis (IIP) that could reduce pedicle-screw led deep-bone surgical site infection and screw loosening (due to biofilm formation between bone and screw).

The researchers published their results in a Global Spine Journal article, “Efficacy of Intraoperative Implant Prophylaxis in Reducing Intraoperative Microbial Contamination,” and numerous conference proceedings.

The participating researchers included Boren Lin, Ph.D.; Jeffrey C. Wang, M.D.; Christian Schultz, M.D.; Dean Steve R. Garfin, M.D.; Vijay K. Goel, Ph.D.; Neel Anand, M.D.; Anand K. Agarwal, M.D.; Hossein Elgafy, M.D.; Dennis McGowan, M.D.; Josue P. Gabriel, M.D.; and Chris Karas, M.D. who are associated with University of Toledo in Toledo, OH; USC Spine Center in Los Angeles, CA; Apex Spine Center in Munchen, Germany; University of California in San Diego, CA; Spine Institute of Ohio in Hilliard, OH; OhioHealth Grant Medical Center in Columbus, OH; Kearney Regional Medical Center in Kearney, NE; and Cedars Sinai Medical Center in Los Angeles, CA.

To avoid intraoperative contamination, Agarwal and colleagues implemented a method of shielding the pedicle screws intraoperatively using a guard. General surgeons and plastic surgeons already do this, using wound edge protectors and Keller funnels to provide a better barrier against contamination.

In their multicenter studies, the researchers used two groups of prepackaged, sterile, single-use pedicle screws: the first group had an intraoperative guard and the second group did not have a guard. Each group consisted of 26 samples that were distributed over 23 time points (independent spinal fusion surgeries). Each was performed in a different operating room by different surgeons and surgical staffs.

During surgery, each of the screws were loaded on insertion devices by the scrub tech and was left on the sterile table. Approximately 20 minutes later, the lead surgeon who had just finished preparing the surgical site checked the pedicle screw for alignment. Then, instead of implantation, the screws were transferred to sterile containers using fresh sterile gloves for bacterial analysis.

Spectrophotometry detected saturated levels of turbidity within 24 hours for the group of screws that did not have a guard. The standard unguarded pedicle screws presented bioburden in the range of 10⁵ to 10⁷ (colony forming units/implant). The strains of bacteria that were found on the unguarded screws, included Staphylococcus epidermis, Staphylococcus aureus, Micrococcus luteus, and Staphylococcus pettenkoferi. The group of screws that did have a guard showed no turbidity or bacterial growth for the entire 14-day incubation period.

Significance of the Findings

OTW spoke with Agarwal about his team’s findings. He said, “Our research signifies the utmost importance of: ‘providing sterile implant to the operating theatre, and then making sure it remains sterile.’”

Agarwal explained that, “The likelihood of post-operative infection depends on three factors:

1. the dose of bacteria left from surgery;
2. the virulence of bacteria; and
3. the patient’s immune (natural or boosted by antibiotics) response at the surgical site.

Not all patients will have infections, but some will (the latest research shows 12.7% do; but even if 1% did we should still care).”

“A rate of 10% implies 100,000 people annually just in the U.S. alone. It is in patient’s best interest to be exposed to the least amount of bacterial dose during surgery; many of these patients are also immunocompromised and have at least one associated high-risk factor like older age, obesity, smoking, diabetes mellitus, ischemia secondary to vascular disease, irradiation, etc. that predisposes them to infection.”

Agarwal also noted, “I am interviewing but this research was fostered by Dean Steve Garfin, Profs. Jeffrey Wang, Neel Anand, Anand Agarwal, Vijay Goel, Chris Karas, Hossein Elgafy, Christian Schultz, Boren Lin, Dennis McGowan, Josue Gabriel and many more spine surgeons, scientists and hospital staffs.”

“The clinical evidences that what we have generated was a result of countess collaborations and effort over multiple institutions.”

“In addition to our extensive research work, I also recommend interested readers to other studies like Rehman et al. (2015) for glove change before handling pedicle screws, Leitner et al. (2018) for identifying the association between pedicle screw loosening and bacterial growth at the interface, Eren et al. (2018) for exemplifying reduction in deep bone SSI by disinfecting pedicle screws intraoperatively, etc.”

“We together are engaged in making the fair and evidence-based choices for patients; in absence of an appropriate regulatory or policy oversight on such matters. Hopefully that will follow soon.”

Amen!