Published 8/2/2022
Brandon May

Topical Antibiotics Do Not Increase Nonunion Risk in High-energy Periarticular Tibia Fractures

Topical antibiotics may not increase the risk of nonunion when used in high-energy periarticular tibia fractures, according to study findings presented by Daniel Miles, MD, at the AAOS 2022 Annual Meeting.

Topical intrawound antibiotics have become commonplace to reduce the incidence of postoperative infections, which can be a devastating complication following operation for high-energy tibial plateau and pilon fractures, according to the study authors. “This approach has permeated throughout subspecialties in orthopaedics, including fracture care,” Dr. Miles told AAOS Now. “Topical antibiotics have been shown to be toxic to vital cells involved in fracture healing.”

Dr. Miles, an orthopaedic surgery resident in the department of orthopaedic surgery at the University of Tennessee College of Medicine Chattanooga, noted that studies reviewing intrawound antibiotics for the purpose of reducing postoperative infection are mixed. Most studies are based on type of injury, location of injury, and whether the surgery is elective or a component of acute trauma. “We wanted to determine if the theoretical decrease in infection rate with the use of intrawound topical antibiotics would outweigh a possible increase in the nonunion rate, which is just as devastating of an outcome,” he explained.

The study was a retrospective review of high-energy tibial plateau and pilon fractures conducted between 2017 and 2020 at a single Level 1 trauma center. In total, the review included 222 patients who received ORIF (open reduction–internal fixation) for AO Foundation and Orthopaedic Trauma Association (AO/OTA) type C tibial plateau or pilon factures. Patients were followed for at least 12 months postoperatively. The primary outcome was the frequency of nonunion, and secondary outcomes included superficial and deep postoperative surgical site infections.

The overall mean age was 50.5 ± 14.5 years, and 62 percent of the population were men. There were 121 tibial plateau and 101 pilon fractures in the retrospective cohort. The most common fracture type was C3 (70 percent C3, 19 percent C1, and 11 percent C2).

Among patients who received topical antibiotics at the time of definitive fixation, 21 percent had sustained an open fracture compared to 18 percent of patients who did not (P = 0.62). Patients who received topical antibiotics were significantly more likely to have had a higher AO/OTA subgroup classification (41C, P = 0.01; 43C, P = 0.003), received a Hemovac drain (51 percent versus 15 percent; P <0.001), received an incisional vacuum (68 percent versus 37 percent;>P <0.001), or had a temporary external fixator placed (87 percent versus 69 percent;>P = 0.001) before definitive fixation. Patients who received topical antibiotics were also more likely to have a delay to definitive surgery (13 days versus 9.5 days).

No difference was found between patients who did and did not receive topical antibiotics in regard to the number of superficial and deep infections. Although rates of nonunion were proportionally higher in patients who received antibiotics (15.8 percent versus 8.3 percent), the final adjusted logistic regression model found no significant increase in nonunion with topical antibiotics (odds ratio, 1.75; 95 percent confidence interval 0.66–4.93; P = 0.27).

Regarding limitations, Dr. Miles noted that the researchers attempted to stratify the topical antibiotic burden by extrapolating vancomycin use with vancomycin plus tobramycin, but the “contribution to each group is inconsistent and may have been confounded by increased antibiotic burden in worse injuries.”

“This study suggests topical antibiotic use in tenuous fractures is safe for now,” Dr. Miles concluded. “However, the influence of confounding variables due to the retrospective nature of this study may blur a meaningful and clinically significant effect.”

Dr. Miles stated that orthopaedic surgeons should take additional care when deciding to use topical antibiotics. First, he said, clinicians should consider that the use of topical antibiotics in fracture surgery is considered off-label. “Also, early basic science studies show topical antibiotics are toxic to cells that are vital to fracture healing. Additionally, fractures being treated may already have high-risk soft-tissue injury that predisposes them to nonunion.”

He added that a randomized, controlled trial is needed to examine nonunion rate as the primary outcome. “Nonunion criteria need to be standardized across multiple centers in order to determine a clinical effect,” Dr. Miles said. “Widespread use of topical antibiotics without proper evidence in this patient population should induce caution in surgical decision-making.”

He stated that another future area of investigation is differences in nonunion or infection rates based on where the antibiotics are placed, whether directly on fractures/plates or in the soft tissues during closure. “Surgeon treatment bias will be the most difficult confounder to overcome in these [future] studies, because it has become almost reflexive to place topical antibiotics in worse fractures and/or contaminated soft tissues,” Dr. Miles said. “Investigational institutions would have to be committed to the protocol in all injury types in order to produce accurate results.”

Dr. Miles’ coauthors of “Does Local Antibiotic Powder Affect Nonunion Risk in Operatively Treated Tibial Plateau and Pilon Fractures?” are Luis Felipe Colon; Mila Scheinberg; Michael Yee, DO; Bryce Alan Cunningham, MD; Jesse Forbes Doty, MD; Warren Ewing Gardner, MD; Dirk W. Kiner, MD; and Peter J. Nowotarski, MD.

Brandon May is a freelance writer for AAOS Now.