Jennie McKee

According to a paper presented yesterday, custom-made antibiotic-impregnated cement nails were effective in treating tibial infections that occur in tibia fracture patients who underwent intramedullary (IM) nailing.

Researchers conducted a retrospective study of 32 patients who underwent IM nailing of tibial fractures and in whom deep postoperative infection subsequently developed. They found that 75 percent of infections were cleared through the use of antibiotic-impregnated IM nails. In addition, persistent infections became apparent early, within the first 6 months after insertion.

“Intramedullary infection of the tibia after nail insertion presents a difficult clinical challenge,” they stated, adding that “treatment of the infection is especially challenging when the tibia is not yet healed, as is usually the case at the time of infection.”

According to the researchers, few data are available related to the efficacy of antibiotic nails in treating infection, despite their widespread use. This study, they noted, “provides valuable data on a relatively new treatment modality.”

Retrospective analysis
The investigators searched the billing database of a Level 1 trauma center to identify all patients who underwent IM nailing of tibia fractures between 2000 and 2010 (n = 1,205). A review of the medical charts of those patients found that antibiotic nails were placed in 41 patients to treat deep postoperative infection. Patients were excluded if they did not have at least 6 months of follow-up, unless they had evidence of infection, leaving 32 patients in the study group.

The average follow-up in the study group was 17.6 months (range: 6 to 76 months), and the average patient was 38 years old (range: 17 to 64 years). Study participants included 26 males and 6 females. Of the 32 patients, 30 (94 percent) had initial open fractures. Compartment syndrome developed in one of the two patients with closed fractures, requiring fasciotomies.

Methicillin-resistant Staphylococcus aureus (MRSA) was the most common infecting organism, found in 11 patients (34 percent), although the most common organism in patients with persistent infection was methicillin-sensitive S aureus (MSSA) (Table 1).

A stabilizing core, such as an Ilizarov rod or ball-tipped guidewire (based on the surgeon’s preference), was used as the core of the antibiotic nail. Vancomycin was then added to polymethylmethacrylate that already contained tobramycin. The authors noted that although it was not standardized in this study, 6 to 8 of vancomycin can be added to each 40 packet of cement to promote maximum efficacy. A 40 French chest tube is used as the antibiotic nail mold, and the cement is injected while still very liquid.

The surgeon’s preference, as well as each clinical scenario, also determined the number of subsequent débridement procedures and the number of exchange antibiotic nail insertions. For a minimum of 6 weeks following insertion of the antibiotic nail, all patients received intravenous antibiotics under the direction of the infectious disease service at the institution. In addition, the treatment course for patients with recurrent infection was also at the surgeon’s discretion and ranged from administration of suppressive antibiotics to revision with a ring fixator.

Analyzing the results
Of the 32 patients in the original cohort, 7 were infected with multiple organisms; 1 patient in the persistent infection group was infected with multiple organisms.

After treatment with the antibiotic-impregnated nail, 24 patients (75 percent) had no evidence of recurrent infection, while 8 patients (25 percent) had persistent or recurrent infections. In all eight patients with persistent or recurrent infection, the infection developed within the first 6 months following insertion of the antibiotic nail. Treatment of these patients was as follows:

Implications and limitations
The authors assert that one way of accomplishing the two goals of treatment—clearing the infection and healing the fracture—is to administer high concentrations of antibiotics inside the IM canal and provide some stability to the unhealed fracture.

Previous studies have found good results with this method; however, these studies have included mixed cohorts of patients with infections of the femur, tibia, and humerus. This study, in contrast, focused solely on the tibia to obtain data on this specific patient cohort.

“Our study showed that antibiotic nails are effective in the treatment of infected tibial fractures,” the authors stated, while noting that more study is needed to compare the effectiveness of antibiotic nails to other treatment strategies.

The study was limited in that it was a retrospective case series, which lacked standard protocols related to the numbers of débridement procedures and nail exchanges. Instead, the treating surgeon’s preference and the clinical scenario dictated these decisions.

Authors of “Do Antibiotic Nails Work for Treating Infected Tibial Fractures?” are Rachel M. Reilly, MD (lead, no conflicts); Theodore T. Manson, MD (senior, no conflicts); and Robert V. O’Toole, MD (Synthes and Stryker). They would like to acknowledge the assistance of Dori Kelly, MA, in preparing the manuscript.