Rectifying Inadequate Debridement And Delayed Tissue Repair In Diabetic Foot Ulcers

The principles of diabetic foot ulcer management are well delineated in the United States as well as European and international guidelines.^1,2 These guidelines universally recommend debridement, when not contraindicated, of all nonviable tissue.  

Extensive literature is available from numerous medical sources supporting the purpose and benefits of wound debridement, including debridement of diabetic foot wounds. We know nonviable tissue promotes bacterial proliferation, which may lead to infection, increase inflammatory protease activity and delay wound closure.³ Nonviable cells not only lack the ability to proliferate, act as chemical mediators and aid in the repair process, they also no longer have active receptor sites needed for intra- and extracellular communication. The absence of cell receptors may negate the benefit of many expensive biological and pharmacological agents.

Growth factors, including those that clinicians apply topically to a wound bed, cytokines and living cell materials must interact with the wound environment to achieve the desired effects.⁴ When the wound bed contains primarily necrotic or nonviable tissue, advanced active modalities are ineffective and wasted.  

Necrotic tissue and high levels of bacteria also increase the levels of inflammatory matrix metalloproteinases, which are known to degrade any protein-based product. As growth factors, living cell products and even acellular matrices are protein-based, I believe the lifespan of these products in the wound is limited, resulting in minimal to no benefit from product application. Researchers have shown that application of expensive topical prescription growth factors, such as platelet-derived growth factor (PDGF), are of significant benefit to wound repair when one applies them to the appropriately selected and prepared diabetic foot ulcer.⁵ However, in the presence of high inflammatory protease activity, which may result from increased bacterial load or a high percentage of necrotic tissue, the growth factor may rapidly degrade and become inactive.

Nonviable tissue can also have a negative impact on device effectiveness. The success of negative pressure wound therapy (NPWT) depends on a variety of factors, one of which is the percentage of viable tissue present in the wound bed. Manufacturers recommend debridement of the majority of nonviable tissue prior to the application of NPWT. A healthcare provider who intends to use any product on a diabetic foot ulcer must first ensure that the wound has had adequate debridement. Failure to ensure appropriate wound bed preparation prior to NPWT increases the cost of patient care while minimizing the benefit of the chosen device.  

An Overview Of The Types Of Debridement
Many guidelines as well as consensus publications list the methods of wound debridement.^1,2 These include mechanical, biological, autolytic, enzymatic and surgical approaches. The choice of the type of debridement primarily depends on the medical status of the patient, wound status and the availability and familiarity of products to the healthcare provider.

The most rapid and effective form of debridement is still full excision of the wound to create a clean, viable wound while converting a chronic wound to an acute one. Provided one has performed a complete patient examination, especially the assessment of vascular status, and the healthcare provider is licensed and competent to perform the procedure, I have found the surgical approach is the most successful one.

Surgical tools, including hydrosurgery, are particularly effective in wound bed preparation as they not only assist with selective excision of nonviable tissue but evacuate the excised tissue along with any bacteria in the debrided area. A surgical blade may reintroduce bacteria into deeper tissue unless one changes it for a clean blade in the final stages of debridement. Hydrosurgery, through tissue and bacterial evacuation, avoids the latter problem. Hydrosurgery is not effective on all types of tissues and requires an understanding of the mechanism of action as well as experience with use of the instrument. Hydrosurgical debridement is best suited for intraoperative procedures although it is not contraindicated in the outpatient setting.

A clear understanding of the local anatomy and safety of debriding in the area of the ulcer is essential. The clinician must also be able to address any post-debridement issues, including bleeding. Following debridement, a clear understanding of the most appropriate dressing will further assist with optimal outcomes. Debridement aside, one must observe all principles of diabetic foot care, including offloading of the foot, as debridement is only one of the principles of diabetic foot ulcer management.

Case Study: When A Lack Of Debridement Leads To A Chronic DFU
The following clinical case is a classic example of the importance of debridement and subsequent care. A 43-year-old male with type 2 diabetes and without additional significant medical problems presented to an outpatient clinic with a plantar ulcer in the right foot that was present for over eight months (see photo on first page at left).  

The wound originated from trauma to the plantar foot. The patient had treatment with a variety of dressings including hydrogel, gauze, topical gels, foam dressings, alginates and antimicrobial dressings without a significant change in wound size. The patient’s blood glucose was well controlled. I identified no other significant problems in the patient’s past or current medical history, or physical examination. There were no clinical or other signs of infection. Vascular flow to the lower extremity and the area of the wound was adequate for healing.

Physical examination of the wound revealed a full-thickness plantar diabetic ulcer without clinical signs of infection. The wound bed was covered with indurated, desiccated and fibrotic tissue with a low level of serous exudate. The wound borders appeared to have a minimal amount of callus. The patient never had wound debridement.

Following cleansing and prepping of the foot, I performed sharp surgical debridement in the outpatient clinic. The photo at right illustrates a clean, viable wound bed. After attaining hemostasis with gentle pressure, I redressed the wound with an antimicrobial silver dressing. The patient got instructions to change the dressing every three days and continue offloading. Subsequently, the wound progressed to granulation and closure over a period of less than two months.

There are a few key points to consider from this case study.

1. In the absence of systemic factors that delay healing, a wound may remain recalcitrant to care without wound bed preparation.
2. Surgical debridement, when indicated, is rapid and effective. When surgical debridement is contraindicated or not possible, consider other modalities including enzymatic and autolytic debridement.
3. Following debridement, one must still ensure appropriate wound dressing selection, offloading, control of diabetes, patient education and other principles of wound management.

In Summary
Appropriate and complete debridement is an essential part of diabetic foot ulcer care. Minimal, incomplete or incorrect debridement may lead to poor treatment outcomes while defeating the purpose of using advanced technologies including biological materials, wound matrices and prescription growth factors. I strongly encourage the clinician to follow all the recommended guidelines and principles of diabetic foot ulcer care at every visit.

Dr. Mulder is a Professor of Surgery and Orthopedics at the Wound Treatment and Research Center at the University of California, San Diego.

References

1. Wound Healing Society. Chronic Wound Care Guidelines. 2007. Available at www.woundheal.org/documents/final_pocket_guide_treatment.aspx .
2. International Diabetes Federation. IDF Clinical Practice Guidelines. Available at www.idf.org/guidelines . /
3. Enoch S, Harding K. Wound bed preparation: the science behind the removal of barriers to healing. Wounds. 2003;15(7):213-29.
4. Mast BA, Schultz GS. Interactions of cytokines, growth factors and proteases in acute and chronic wounds. Wound Repair Regen. 1996;4(4):441-230.
5. Feng RC, Galiano RD. A review of becaplermin in the treatment of diabetic neuropathic foot ulcers. Biologics. 2008; 2(1):1-12.

For further reading, see “Can Ultrasound Debridement Facilitate Biofilm Removal From Diabetic Foot Ulcers?” in the August 2014 issue of Podiatry Today, “Current And Emerging Modalities In Wound Debridement” in the August 2013 issue or “Pertinent Insights On Effective Debridement Tools” in the September 2011 issue.