Can The Combination Of Serial Irrigation And Debridement With Antibiotic Beads Have An Impact For Severe DFIs?

There were over 65,000 hospital admissions for amputation in patients with diabetes across the United States in 2009.¹ This does not take into account hospital admissions for foot infection that did not lead to amputation or that occurred in patients without diabetes. Although the number of hospitalizations for amputation per 1,000 patients with diabetes has been trending downward since 1996, the number of U.S. patients diagnosed with diabetes has been steadily increasing to a level of 20.9 million in 2009.¹ This translates to a likely increase in the number of hospitalizations for diabetic foot infection over time.

Therefore, foot and ankle surgeons must be fully prepared to manage these infections in order to provide the best possible outcome for the patient. A multidisciplinary approach is recommended to address comorbidities such as peripheral arterial disease, poorly controlled diabetes, renal disease and malnutrition, and to aid with management of psychosocial issues that could impair recovery. Involvement of an infectious disease specialist can be helpful in determining antibiotic selection and the duration of administration.^2-6 When patients require surgery, a specific protocol is beneficial in providing reproducible control of infection and can help facilitate improved long-term outcomes.

In a retrospective review of patients who had serial irrigation and debridement with polymethylmethacrylate antibiotic (PMMA) bead placement from March 2009 through October 2015, I recorded patient demographics, the type of surgery, time to healing, the number of procedures, residual bacterial growth, postoperative complications and recurrent ulceration. All patients were admitted to the hospital during the surgical phase of treatment. Postoperative instructions were dependent upon the procedure(s).

All of the patients in the study had irrigation and debridement (I&D) with wide excision of all infected soft tissue and bone, and subsequent pulse lavage irrigation of 2-4 liters of normal saline. In order to reduce spatter, I performed pulse lavage with the patients’ limb inside an X-ray cassette bag and a hole cut distally to facilitate irrigation. I obtained aerobic and anaerobic cultures of the surgical site after normal saline irrigation to identify any residual bacteria. Then I repeated pulse lavage with 2 liters of normal saline mixed with 50,000 units of bacitracin.

The patients subsequently received PMMA beads that were approximately 7 mm in diameter and comprised of 160 mg of gentamicin liquid and 600 mg of vancomycin powder. After attaching the PMMA beads to 2-nylon and inserting them into the surgical site, I applied a dry, sterile dressing. The beads were untouched for at least three days postoperatively. Then there was a repeat I&D with wound closure if the tissues were adequately clean. Some patients required additional I&D procedures with PMMA bead placement prior to definitive wound closure and some wounds in other patients closed by secondary intention after I performed the last I&D procedure. Anderson, Roukis and Schade previously described a similar protocol.^3,7

What The Retrospective Study Results Revealed
There were a total of 21 I&D procedures in 19 patients. One patient had initial serial I&D procedures for a partial, right first ray resection in November 2013 and received subsequent treatment for a recurrent ulceration with osteomyelitis plantar to the right second metatarsophalangeal joint (MPJ) in September 2014. Another patient had serial I&D procedures on bilateral feet.

All of the patients were male and ranged between 40 to 71 years of age at the time of surgery. Sixteen patients (84 percent) had diabetes with a hemoglobin A1C (HgA1C) ranging from 5.7 to 13.4. Two patients (10.5 percent) had peripheral arterial disease (PAD). Three patients (15.8 percent) were current smokers.

Aerobic cultures after initial debridement were negative after 13 (62 percent) of the I&D procedures. In regard to the other eight procedures, four had no growth on cultures after the second procedure. Of the 21 cases, 17 (81 percent) had two I&D procedures and four (19 percent) had three I&D procedures. There was wound closure by secondary intention in one patient, final delayed primary closure at bedside with the use of a skin expander for another patient and primary closure at the completion of the last I&D for all other procedures. Healing time varied from three weeks to 6.5 months.

Complications included four patients (21 percent) with some level of delayed healing or wound dehiscence, all of which healed with local wound care. One patient had an antibiotic bead left in at the time of wound closure and required an additional surgery to remove it. To avoid this, surgeons should count and document the number of beads inserted on the operative report or use intraoperative fluoroscopy to ensure all beads are removed at the time of surgery, particularly for deep wounds.

Five patients (26.3 percent) had recurrent ulceration. One ulcer occurred at the distal stump of a transmetatarsal amputation in a patient, who was treated at another facility with an unknown outcome. Another ulcer was at the base of the fifth metatarsal after a partial fifth ray resection, which eventually healed with local wound care. There was one transfer ulcer under the second MPJ after partial first ray resection that resulted in osteomyelitis with the subsequent need for amputation. Another patient had a recurrent ulceration at the I&D site plantar to the first MPJ, which I treated with local wound care.

Another patient had one ulcer medial to the second MPJ after a partial first ray resection and is currently receiving treatment. Recurrent cellulitis without recurrent ulceration occurred in one patient (5.3 percent) and I managed this with antibiotic therapy. Only one patient (5.3 percent) underwent a subsequent amputation on the same foot after healing of the initial procedures. Follow-up ranged from eight weeks to five years. However, for two patients, long-term follow-up occurred through progress notes from other facilities where patients had moved. Five of the patients are now deceased but this was unrelated to their foot surgery.

Can Serial Debridement Play A Key Role In Treating Diabetic Foot Infections?
Foot infections, especially in high-risk patients such as those with diabetes and peripheral arterial disease, can be difficult to treat and often lead to major amputations. Multiple authors have described the use of serial debridement as part of a protocol for limb salvage and found a reduction in below- and above-knee amputation.^5,8 Saving a usable and stable portion of the foot is beneficial for retaining an individual’s independent mobility and improving life expectancy.⁹ It has been well documented that the energy expenditure required to ambulate with a below- or above-knee amputation places greater stress on the heart, often leading to increased mortality rates.^10-13 Some patients are unable to return to their preoperative functional level, particularly if they had impaired ambulatory ability prior to amputation.^14-17 Patients undergoing below- or above-knee amputations secondary to critical limb ischemia also tend to have lower rehabilitation potential.^17-18

Although limb salvage can be a long process with many potential complications, the patients in the aforementioned retrospective study had good overall long-term results. Fifteen patients (79 percent) were healed within three months of the final surgery and all patients had complete healing by 6.5 months post-op. To date, with most of the patients having follow-up over one year, only one patient had another amputation on the same foot. Bacteria was eliminated after the second I&D procedure in 81 percent of the cases. Of the four patients with delayed healing and dehiscence, two were smokers, one had poorly controlled diabetes (defined as HgA1C greater than 8.0) and one had poorly controlled diabetes and PAD. There were no complications or delays in wound healing in seven (77.8 percent) of the nine included patients with poorly controlled diabetes. In all patients, serial I&D procedures led to predictable success with wound healing and prevented major limb amputation.

In regard to the aforementioned study, there are several weaknesses including the retrospective design, the small number of patients, incomplete follow-up and a lack of detailed statistical analysis of results. The results are not generalizable to the population at large but do show the benefit of following a routine surgical protocol to eliminate foot infection and reliably save limbs in a high-risk patient population.

In Conclusion
A surgical protocol of serial I&D procedures with antibiotic bead placement can lead to predictable control of foot infections in high-risk individuals. Utilizing such a protocol for limb salvage may reduce major amputation rates and lead to a better quality of life for patients.

Dr. Schweinberger is affiliated with the Veterans Affairs Medical Center in Cheyenne, Wyoming. She is a Fellow of the American College of Foot and Ankle Surgeons.

References

1. Centers for Disease Control and Prevention. Crude and age-adjusted hospital discharge rates for nontraumatic lower extremity amputation per 1,000 diabetic population, United States, 1988-2009. https://www.cdc.gov/diabetes/statistics/lea/fig3.htm . Updated October 2, 2014. Accessed March 10, 2016.
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15. Taylor SM, Kalbaugh CA, Cass AL, et al. “Successful outcome” after below knee amputation: an objective definition and influence of clinical variables. Am Surg. 2008;74(7):607-12.
16. Pernot HF, Winnubst GM, Cluitmans JJ, De Witte LP. Amputees in Limburg: incidence, morbidity, and mortality; prosthetic supply, care utilization and functional level after one year. Prosthet Orthot Int. 2000;24(2):90-96.
17. Peng CW, Tan SG. Perioperative and rehabilitative outcomes after amputation for ischemic leg gangrene. Ann Acad Med Singapore. 2000;29(2):168-172.
18. McWhinnie DL, Gordon AC, Collin J, Gray DW, Morrison JD. Rehabilitation outcome 5 years after 100 lower limb amputations. Br J Surg. 1994;81(11):1595-1599.

For further reading, see “An Update On Antibiotic Resistance And DFUs” in the March 2016 issue of Podiatry Today. For an enhanced reading experience, check out Podiatry Today on your iPad or Android tablet.