A Closer Look At The Role Of Collagen In Healing Complex Diabetic Foot Ulcerations

By Ann Zmuda, DPM

Case Study: When A Patient Presents With A Chronic Open Sore Of Eight Months’ Duration On His Left Foot

The photo on page 1 shows a wound in a 46-year-old male patient who presented with a wound infection in the left foot. He had incision and drainage on the dorsal and plantar aspects of his left foot. He did not follow up with his previous physicians and presented eight months later complaining of a non-healing open sore on the bottom of his left foot.

   The patient’s past medical history included poorly controlled diabetes diagnosed at the age of 20, hypertension, dyslipidemia, chronic renal insufficiency, anemia, cataracts and a traumatic right leg disarticulation at the age of 9. He ambulates with a right prosthesis. The patient worked as a full-time janitor and had to walk five blocks to and from work. He adamantly refused any surgery as he could not miss work and was afraid of losing the only leg he had.

   The wound was initially 4.5 x 3.0 cm with a 0.4 cm depth. Over a two-month time period, his treatment consisted of several various regimens, including an offloading wedge shoe, oral antibiotics, sharp debridement, topical enzymatic debriding agents, silver dressings and total contact casting. Despite these efforts, the wound had increased in size to 5.5 x 4.7 cm with a depth of 0.4 cm and signs of infection. Lab values included C-reactive protein of 44 mg/L, an erythrocyte sedimentation rate of 108 mm/hr, a white blood cell count of 7.7 K/μL, mg/dL and HbA1c of 10.1%.

   At this point, magnetic resonance imaging (MRI) revealed fat between the ulcer and the first metatarsal head with intermediate signal intensity on T1 and T2 weighted images. There was abnormal signal intensity on T1 and T2 weighted images in regard to the marrow of the medial sesamoid bone that was compatible with osteomyelitis. There were also an increased T2 signal and a normal T1 signal within the lateral sesamoid and proximal phalanx of the great toe.

Keys To Treatment

I recommended surgical intervention as well as intravenous antibiotic therapy to try to save the limb. The procedure consisted of medial and lateral sesamoid removal, first metatarsal head resection through a dorsal incision, incision and drainage of the plantar ulceration with the use of Versajet (Smith and Nephew), and the subsequent application of the Integra Bilayer Matrix Wound Dressing (Integra LifeSciences).

   Integra is an advanced wound care dressing comprised of a porous matrix of cross-linked bovine tendon collagen and glycosaminoglycan, and a semi-permeable polysiloxane (silicone layer). The semi-permeable silicone membrane controls water vapor loss, provides a flexible adherent covering for the wound surface and adds increased tear strength to the device. The collagen-glycosaminoglycan biodegradable matrix provides a scaffold for cellular invasion and capillary growth.7 I chose this product to provide wound coverage and the structural support needed to complete the wound healing process.

   The patient tolerated the anesthesia and procedures well, and wore a wedge shoe for offloading. At the first postoperative visit, there was healthy granulation tissue through the intact silicone layer of the Integra graft. At three weeks, I removed the staples and silicone layer, and there was a healthy, healing wound bed. Approximately six weeks later, the wound was healed and the patient was able to return to work in protective shoe gear.

In Conclusion

This is just one example of the many collagen products available for use in the treatment of complex diabetic foot ulcerations. It also illustrates the use of surgical as well as advanced wound technology methods to salvage these high-risk limbs. Belatti and colleagues recently published a study showing a marked decline in the use of lower extremity amputations in the Medicare population over the last decade as well as an increase in distal, limb-conserving amputation locations, and a sharp increase in orthopedic/surgical treatments for diabetic foot ulcerations.8 However, one must never neglect the basic fundamentals of wound care including debridement of non-viable tissue, offloading, resolution of infection and adequate perfusion.

   Dr. Zmuda is an Assistant Professor in the Section of Endocrinology in the Department of Orthopedic Surgery at the University of Chicago.

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