Commentary & Perspective

Commentary & Perspective on
"Comparison of Soap and Antibiotic Solutions for Irrigation of Lower-Limb Open Fracture Wounds: A Prospective, Randomized Study"
by Jeffrey O. Anglen, MD, et al.

Commentary & Perspective by
Mohit Bhandari, MD, MSc, FRCSC, Brad Petrisor, MD, MSc, FRCSC, and Emil H. Schemitsch, MD, FRCSC*,
Hamilton Health Sciences-General Hospital, Hamilton, Ontario, Canada

Patients with open fractures are at risk for the development of an infection, and the rate of infection can be as high as 50% if the open fracture is severe or becomes grossly contaminated due to the mechanism of injury¹. The single most important step in the initial management of open fractures is a thorough irrigation and débridement². Removal of all remaining contaminated tissues and foreign matter can be accomplished with copious irrigation of the wound. However, there is currently no clinical evidence with regard to the optimal volume or pressure of irrigation, whether pulsatile irrigation is preferable to nonpulsatile, or whether the type of additive influences infection rates and other important outcomes. The type of irrigating solution and its effect on the efficacy of wound débridement remains controversial.

Experimental studies have evaluated several irrigation additives, including antiseptics, antibiotics, and surfactants. Antiseptics have been shown to be toxic to host cells². Although antibiotics (such as bacitracin) and surfactants (such as castile soap) are routinely used for open wound irrigation, their relative effect on clinically important outcomes remains unknown. Laboratory studies found soap solution to be more effective than normal saline solution for the purpose of removing bacteria^3,4, but soap solution may be more effective for removing some types of organisms than others.

In an in vitro calvarial cell culture model, 1% soap solution preserved both alkaline phosphatase activity and bone nodule formation to the greatest extent when compared with other solutions (p < 0.05)³. Moreover, the soap solution preserved osteoclast numbers to the greatest extent. Povidone-iodine and chlorhexidine solutions resulted in the greatest decline in bone nodule formation, alkaline phosphatase activity, and osteoclast numbers (p < 0.001). The addition of a soap solution under low-pressure pulsatile irrigation removed the greatest number of bacteria from the contaminated tibia when compared with either the soap alone or the low-pressure irrigation alone (p < 0.01). Until now, we have relied primarily on such experimental data to drive much of our decision-making regarding wound irrigation.

Dr. Anglen should be commended for conducting a well-designed clinical trial of 400 patients with 458 open fractures to compare whether the addition of a detergent (castile soap) versus an antibiotic (bacitracin) additive to the irrigating fluid affects rates of infection, wound healing, and fracture healing. This study has several strengths, including randomization, concealed treatment allocation, standardization of interventions by an experienced trauma surgeon, clearly defined and objective measures of outcome, and a high follow-up rate (88%).

Anglen reports that castile soap led to a significant reduction in wound healing complications compared to bacitracin (eight of 199 [4%] vs. nineteen of 199 [9.5%]; p = 0.03). We can communicate this finding to patients as a relative risk reduction. Thus, castile soap solution reduced the risk of wound-healing complications by 58% (95% confidence interval: 1% to 73%). In addition, for every eighteen patients treated with castile soap instead of bacitracin, one adverse wound healing event can be prevented (Number needed to treat, 18.1).

The study had sufficient power (80%) to detect a 10% difference in infection rates between groups, assuming a 20% prevalence of infection in the bacitracin group; however, he found a 5% absolute difference between groups (p = 0.2). Although the findings are not statistically significant, they do generate important hypotheses and may not entirely represent "no difference." Castile soap reduced the risk of infection by 26% (95% confidence interval: -26%- 55%, p = 0.2). Although the study has a 28% power for this outcome, we cannot rule out a clinically important benefit to castile soap—or vice versa, a clinically important benefit of bacitracin. The point estimate, however, does suggest that the overall effect may favor castile soap solution. A sufficiently powered study to resolve the infection rates would require at least 1600 patients. Despite the large sample of patients in Anglen's study, a study four times larger may be needed to resolve this issue definitively. Until such time, Anglen's conclusions that "irrigation of open fracture wounds with antibiotic solution offers no advantages over the use of a nonsterile soap solution, and it may increase the risk of wound-healing problems" is an accurate reflection of current evidence.

The current study utilized a single irrigating pressure via a pressure irrigator (higher pressures) and was therefore unable to resolve the issue of whether different irrigating pressures make a difference in outcomes. The lack of clinical evidence regarding irrigating pressures has been reflected by altering preferences for open wound irrigation among surgeons. In a survey of 577 orthopaedic surgeons managing open tibial fractures, 39% preferred high-pressure irrigation whereas 45% used low-pressure irrigation in their treatment of open wounds⁵. Given the lack of consensus and conflicting biologic evidence, a clinical investigation of irrigation pressure may also be warranted.

In conclusion, the current trial by Anglen provides pivotal information to guide current practice. The estimates it provides to guide further study in the field are as important as its confirmation of the benefits of castile soap on wound healing. This trial has undoubtedly set the benchmark for future study in this field.

*The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

References

1. Tsukayama DT, Schmidt AH. Open fractures. Current Treatment Options in Infectious Diseases. 2001;3:301-7.
2. Anglen JO. Wound irrigation in musculoskeletal injury. J Am Acad Orthop Surg. 2001;9:219-26.
3. Bhandari M, Adili A, Schemitsch EH. The efficacy of low-pressure lavage with different irrigating solutions to remove adherent bacteria from bone. J Bone Joint Surg. 2001;83:412-9.
4. Anglen JO, Gainor BJ, Simpson WA, Christensen G. The use of detergent irrigation for musculoskeletal wounds. Int Orthop. 2003;27:40-6.
5. Bhandari M, Guyatt GH, Tornetta P 3rd, Swiontkowski MF, Hanson B, Sprague S, Syed A, Schemitsch EH. Current practice in the intramedullary nailing of tibial shaft fractures: an international survey. J Trauma 2002; 53:725-32.

Copyright © 2005 by the The Journal of Bone and Joint Surgery, Inc.