Comparison of a Bioimplant Dressing With a Wet Dressing for the Treatment of Diabetic Foot Ulcers: A Randomized, Controlled Clinical Trial

Background. The authors aimed to evaluate the efficacy of a bioimplant dressing in comparison with a wet dressing in patients with diabetic foot ulcers (DFUs). Materials and Methods. Fifty-seven patients with diabetes who had an ulcer of Wagner Grades 2-4 were included in this controlled clinical trial. The study was conducted in the outpatient diabetic foot clinic of Dr. Shariati Hospital, affiliated with the Endocrinology and Metabolism Research Institute, Tehran University of Medical Sciences, Tehran, Iran, from November 2010 to March 2012. Fifty-seven cases of DFUs were equally and randomly divided into control and test groups. The bioimplant group received an amniotic membrane dressing while the control group was treated with a wet dressing. Both groups were evaluated once a week for 6 weeks for the degree of epithelialization and granulation tissue of the wound. Results. The complete healing rate (ie, wound closure) in the whole study population was 28.1% (control group, 16.7%; bioimplant group, 40.7%, P = 0.04). In 21 patients (77.77%) of the bioimplant group, granulation tissue was extended within the third visit. Amputation and hospitalization rates were higher in the control group compared to the bioimplant group; however, the difference was not statistically significant (relative risk [RR]: 1.11, 95% CI 0.91-1.34, P = 0.258; RR: 1.27, 95% CI 0.97-1.66, P = 0.076, respectively). Conclusion. The bioimplant dressing was significantly superior to the wet dressing in prompting the complete healing of DFUs. Ease of use, absence of adverse effects, and a facilitated wound healing process are among properties of amniotic membrane that make it an appropriate dressing in the management of DFUs. Additional research will shed more light on the promising advantages of this material in healing DFUs.

Diabetic foot ulcers (DFUs) are a common complication of diabetes mellitus, which have a major long-term impact on the morbidity, mortality, and quality of patients’ lives. The overall lifetime risk of DFUs in patients with diabetes is reported to be 12% to 25%.^1,2 Diabetic foot ulcers have a major economic impact as well; data have shown DFUs are a major cause of hospitalization for patients with diabetes.³ The prevalence of this diabetes-related complication is reported to be considerably high in Iran.^4,5

A DFU is a pivotal event in the life of a person with diabetes as it is one of the complications of diabetes that can be life threatening. Without early and optimal intervention, the wound can rapidly deteriorate, leading to amputation of the affected limb. There are different approaches for the management of DFUs such as achieving optimal diabetic control, removal of pressure, eradication of infection, and proper dressing.⁶  Identifying the underlying cause of the DFU during the patient assessment and, when possible, correction or elimination of that underlying cause is also an important part of DFU management. In addition, preparation of the wound bed by the means of debridement is one of the main cornerstones of any treatment option.⁷ 

Dressing is one of the most important aspects of treatment for DFUs. The aim of dressing application is to provide a moist condition to accelerate the healing process.^6,8 However, there is no single form of dressing suitable for all wounds. In fact, based on the characteristics of DFUs, various types of dressings should be applied to the ulcers.⁸ The most commonly used forms of dressings are nonadhesive dressings, which are simple, affordable, and easy for patient use due to their effectiveness and fewer side effects. Hydrogels are another option for the management of ulcers with necrotic tissue. Dressings containing iodine, silver, and antibiotics have also been applied with the aim of prevention and management of wound infections.⁹

Novel dressing methods for the treatment of DFUs have been developed and applied in recent years.⁶ Tissue-engineered skin (Apligraf, Organogenesis Inc, Canton, MA) is highly effective in terms of acceleration of the healing process and prevention of osteomyelitis and amputation.¹⁰ Recombinant platelet-derived growth factor is another adjuvant therapeutic agent demonstrated to be effective in the treatment of diabetic ulcers.¹¹ Semelil (ANGIPARS, Rose Pharmed, Tehran, Iran), a new herbal extract from Melilotus officianalis, has been formulated by Iranian scientists for the management of DFUs in recent years.¹² It is produced in oral, topical, and intravenous forms. The results of the complete set of preclinical and clinical trials (I-IV) demonstrated this drug is effective and safe.^13-16 

Human amniotic membrane (HAM) has been applied as a biomaterial for the treatment of various wounds, including burns, bedsores, diabetic neurovascular ulcers, and venous stasis ulcers for more than 100 years. It has been suggested that enriched acellular human amniotic collagen membrane (AHAM) could potentially transfer autologous or allogeneic cells and also can be used for the treatment of a variety of conditions, including corneal defects, severe skin burns, and ulcers such as DFUs.¹⁷ It consists of 1 layer of epithelial cells, a basal layer, and a vascular connective tissue matrix. The membrane acts as a natural collagen extracellular matrix and facilitates cell migration.

In the current study, the authors aimed to assess the possible superiority of a new tissue engineered form of wound dressing containing AHAM in comparison with a wet gauze dressing. 

This randomized, controlled clinical trial was conducted at the outpatient diabetic foot center of Dr. Shariati Hospital, affiliated with the Endocrinology and Metabolism Research Institute, Tehran University of Medical Sciences, Tehran, Iran, from November 2010 to March 2012.

Inclusion criteria were male and female patients with diabetes > 18 years of age, who had DFUs with Wagner Grade classification 2-4; who had an ankle-brachial index (ABI) of ≥ 0.5; and who had a wound size of at least 2 cm². Patients excluded from the study were those with chronic kidney diseases (Cr ≥ 2.5 mg/dL) or cardiopulmonary diseases, with poorly controlled diabetes (HbA1c ≥ 10%), or with a Michigan Diabetic Neuropathy Screening Score (MDNS) ≤ 3; pregnant women; patients taking immunosuppressive medications; smokers; and recreational drug users.

The Ethics Committee of Tehran University of Medical Sciences approved the study protocol. All patients signed the written informed consent form after receiving adequate information about the study. Participants were then matched and assigned to receive either the bioimplant dressing, a tissue-engineered form of wound dressing containing AHAM (Life Patch, International Bioimplant Company, Tehran, Iran) or wet dressing. 

The bioimplant dressing is composed of a single layer of epithelial cells, a basement membrane, and a vascular connective tissue matrix. To produce these patches, donor mothers were screened at delivery for infections (HBs Ag, Anti-HCV, Anti-HIV1, Anti-HIV2, Anti-Human T-lymphotrophic virus [Anti-HTLV1, 2], and syphilis), malignancy, and neurological and autoimmune diseases. All the seropositive tissues for the viruses were discarded. The placenta, amniotic fluid, and membrane are typically discarded after childbirth; however, all donors were informed and ethical issues were observed by the manufacturer. Each bioimplant was then processed, sterilized, and stored at -20° C in a clean room in standard conditions. The patches are available in 3 different sizes: 2 cm x 2 cm, 5 cm x 5 cm, and 10 cm x 10 cm, and are stored at -20°C. At the time of application, the patches were softened at room temperature for 5-10 minutes and then directly applied to the wounds as the primary dressing. 

Demographic characteristics of all subjects were recorded. All patients underwent clinical examination and a full medical history was obtained. The results of paraclinical assessment as well as the characteristics of the wounds were recorded. Neuropathy was assessed by means of the MDNS. Peripheral neuropathy was present when the MDNS score ≥ three eighths.¹⁸ Vascular assessment was performed based on clinical examination and ABI measurement. Patients with an ABI < 0.8¹⁹ were considered to have peripheral vascular disease.

Patients were then randomized into 2 groups using a simple randomization method: one group (n = 27) was treated weekly with the bioimplant as the authors’ treated group and the other group (n = 30) was treated with the wet dressing as control. Patients were examined weekly up to a maximum of 6 weeks (42 days ± 2 days) if complete wound closure had not occurred. In cases of complete wound healing before 6 weeks, followup was ceased. During each examination of patients in both groups, wounds were first washed with sterile normal saline solution, and then calluses and necrotic tissues were removed surgically (layer by layer) until normal, healthy tissues appeared. In the next step, wounds were measured using a ruler, and a photograph was taken using a digital camera. Infection assessment was done by evaluation of the following parameters: secretion, erythema, edema, and fever. Patients received systemic antibiotics when indicated.

In the bioimplant group, the bioimplant dressing was applied directly to the wound bed in the clinic and then covered with gauze and fixed with an adhesive tape. Physicians applied the dressing weekly in the clinic; however, the patient changed the gauze and adhesive tape daily. 

Wounds in the control group were covered with sterile saline-moistened gauze before the dressing was secured with a bandage and adhesive tape. The patients changed their dressing daily, and the physician visited them weekly in the clinic. 

The state of healing was assessed by clinical examination, and final healing was defined as complete re-epithelialization of the wound in the absence of discharge. Wound surface area was measured with the use of image analysis computer software (Osiris 4.19, University of Geneva, Geneva, Switzerland). Any potential diabetes-related complication (eg, infection, necrosis, or allergic reaction) was recorded. The proper offloading devices such as half-shoes, felted foam, and pads were recommended to patients who had ulcers on weight-bearing sites.

Statistics
The primary objective of the study was to determine the percentage of patients with complete reepithelialization in their wounds or wound closure within the 6-week study period. Secondary objectives included 50% or greater reduction in the wound surface area, hospitalization, and the amputation rate at the end of the study period.

Data were analyzed using SPSS version 16 for Windows (SPSS Inc, Chicago, IL). The continuous variables were expressed as mean ± standard deviation, and categorical variables were expressed as frequencies (%). The mean difference of continuous variables between groups was assessed by Student t test. The comparisons of qualitative variables between groups were performed by χ2 test. The repeated measures analysis of variance (RMANOVA) test was used to compare the mean wound surface area between the bioimplant and wet dressing groups in various time intervals. A P value of < 0.05 was considered statistically significant

A total of 57 patients with diabetes (37 males and 20 females) with a mean age of 57.8 years ± 10.4 years were recruited in this study. There were no statistically significant differences with respect to demographic or baseline clinical presentations between the 2 groups (Table 1). 

At the baseline, the mean wound surface area was 948.15 mm² ± 935 mm² and 860.9 mm² ± 1005 mm², in the bioimplant and wet dressing groups, respectively. The mean duration of ulcer development was 37.1 weeks ± 24.8 weeks in the tissue-engineered form of wound dressing containing the AHAM group and 28.5 weeks ± 28.37 weeks in the wet dressing group. After 6 weeks, the overall complete healing rate among all patients was 28.1%. More than 50% reduction in mean wound surface area was seen in 48.1% of the patients treated with the bioimplant compared to 20% of the patients treated with wet dressings (P = 0.024). Complete wound healing occurred in 11 patients (40.7%) of the bioimplant group and in 5 patients (16.7%) of the control group (P = 0.04; Figure). In 21 patients (77.77%) of the bioimplant group, granulation tissue was extended within 3 weeks. 

Application of the 2-way repeated measurement method revealed a significant difference in wound size reduction percentage and healing rate between the 2 groups after 6 weeks (Table 2; Figure). 

Although both amputation and hospitalization rates were higher in the control group compared to the bioimplant group, these differences did not reach a significant level (Table 3) (relative risk [RR]: 1.11, 95% CI 0.91-1.34, P = 0.258; RR: 1.27, 95% CI 0.97-1.66, P = 0.076, respectively). 

Human amniotic membrane has been widely used in many surgical procedures dating back to the beginning of the last century when fetal membranes were used in skin transplantation to treat burned and ulcerated skin.²⁰ In the present study, the authors evaluated the efficacy and safety of AHAM as a bioimplant topical wound dressing material in patients with DFUs. They found a significantly higher percentage of patients (40.7%) in the bioimplant group achieved complete wound healing in 6 weeks, compared to the patients in the wet dressing group (16.7%). The results of the study demonstrated that within the study period, the use of AHAM in combination with appropriate wound care, including standard debridement and offloading if needed, is associated with a significantly higher rate of wound surface area reduction in comparison with the control.

Acellular human amniotic membrane has some biological properties that make it a valuable material for several medical purposes. When used as a wound dressing, this material is known to better control infection as well as promote wound healing via its anti-inflammatory, antimicrobial, antifibrosis, and antiscarring characteristics, as well as its low immunogenicity.²¹

Better management of DFUs using amniotic membrane has been reported by other researchers. Letendre et al²² evaluated the application of a decellularized, dehydrated human amniotic membrane (BIOVANCE, Alliqua BioMedical, Yardley, PA) to determine the healing rates for partial-thickness or full-thickness noninfected DFUs over a 12-week period in 13 patients. The 9 patients who completed the 12-week study period were categorized as follows: group 1 consisted of 5 patients (55.5%) with 100% wound closure, group 2 consisted of 3 patients (33.3%) with 50% to 100% wound closure, and group 3 consisted of 1 patient (11.1%) with < 50% wound closure. Although complete wound closure was not achieved in all patients enrolled in this study, the percentage of wounds that positively responded to the treatment (88.8%) was significantly higher in the decellularized, dehydrated human amniotic membrane group compared to the control group. In addition, Letendre and colleagues²² reported no adverse events with this product.

In a prospective comparative study in India,²³ 200 cases with nonhealing lower limb ulcers (eg,  ischemic, neuropathic, venous, and posttraumatic wounds) were randomly assigned to either receive the amniotic membrane dressing or the normal saline dressing. Among the enrolled patients, 66 had diabetes mellitus. Patients were evaluated and compared at the end of weeks 1, 2, and 3 according to ulcer epithelialization, percentage of granulation tissue, pain control, and infection prevention. By the end of the third week, 88 patients in the test group showed epithelialization as compared to 52 in the control group (P < 0.001). The authors concluded that amnion is a good material for the treatment of nonhealing ulcers.²³

In a randomized, controlled, single-center trial, Zelen et al²⁴ compared the efficacy of dehydrated amniotic membrane graft (EpiFix, MiMedx, Marietta, GA) in the treatment of diabetic lower extremity ulcers versus standard care treatment. Following surgical debridement, all patients underwent weekly dressing changes. In the dehydrated amniotic membrane graft group, 92% of patients achieved complete wound healing in 6 weeks compared to 8% in the standard care treatment group. 

In the present study, the rate of complications such as amputation and hospitalization was lower in the bioimplant group compared with the wet dressing. However, this difference was not statistically significant.

Werber and Martin²⁵ treated 20 foot and ankle chronic wounds (14 ulcers were attributed to diabetic neuropathy and 6 to arterial insufficiency) with cryopreserved amniotic membrane and fluid allografts for 12 weeks. Among the 20 patients, complete healing occurred in 18 subjects (90%) and none required amputation.

Abrams²⁶ treated 20 patients who failed to have at least 50% closure within 4 weeks of standard treatment with a processed human amniotic membrane allograft (EpiFix, MiMedx, Marietta, GA). The results were 100% full closure, and 42% and 50% reduction in cost and time to closure, respectively. 

There are some limitations attributable to the current study. First, patients who had neuropathic (ABI > 0.8) or neuroischemic (ABI = 0.5–0.8) ulcers were recruited in this study. Moreover, the authors did not compare the response to treatment based on the ulcer type (ie, neuropathic or neuroischemic).

The results of the present study demonstrated the bioimplant dressing tested can be considered an effective adjunctive treatment in the promotion of wound healing in patients with DFUs. Furthermore, the availability, easy application, and affordability of amniotic membrane make it a superior dressing option in the management of DFUs. However, further research is warranted to shed more light on the advantages of this novel dressing for DFUs.

The authors would like to acknowledge the Endocrinology and Metabolism Research Institute and the Center for Research and Training in Skin Diseases and Leprosy for providing patients and the necessary staff for this study. 

Affiliations: Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran; Center for Research and Training in Skin Disease and Leprosy, Tehran University of Medical Sciences; and Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences

Correspondence:
Bagher Larijani, MD
Professor of Endocrinology and Metabolism
Endocrinology and Metabolism Research Institute
Tehran University of Medical Sciences
5th Floor, Dr. Shariati Hospital
North Kargar Avenue
Tehran, Iran 14114
emrc@tums.ac.ir

Disclosure: The International Bioimplant Company (Tehran, Iran) provided the dressing tested in this study.