The Use of Bovine Collagen-glycosaminoglycan Matrix for Atypical Lower Extremity Ulcers

The primary purpose of this study was to evaluate the use of bovine collagen-glycosaminoglycan matrix on atypical lower extremity ulcers. A retrospective chart review was performed on patients who underwent application of bovine collagen matrix to a lower extremity ulcer with an atypical etiology including autoimmune disease, sickle cell anemia, radiation therapy, connective tissue disease, vasculitis, or coagulopathy from January 2009 to October 2014. The following outcomes were evaluated: rate of ulcer healing and closure, number of ulcers that received a split-thickness skin graft, improvement in pain, and complications related to the ulcer.Thirty-eight patients with 71 lower extremity ulcers were analyzed. The most common ulcer etiologies included rheumatoid arthritis, sickle cell anemia, and coagulopathy. After application of the bovine collagen matrix, 30 (42.3%) ulcers healed at a mean of 220.9 days. Of the 71 ulcers, 26 (36.6%) received a split-thickness skin graft after application of the matrix and 17 (65.4%) of those went on to complete healing. Ten patients had a local infection noted during follow-up, and 5 patients had dehiscence or dissociation of the matrix. Atypical lower extremity ulcers, such as those caused by autoimmune diseases and sickle cell anemia, proved difficult to heal. This case series shows that bovine collagen matrix can be a successful adjunctive therapy for the treatment of these challenging ulcers.  

Chronic lower extremity ulcers are an ever-growing health care problem and show a significant burden to the patient and health care team.^1,2 The potential etiologies for lower extremity ulcers is extensive, with the most common causes being venous disease, arterial occlusive disease, and neuropathic disease.^3,4 Uncommon or atypical etiologies include ulcers due to systemic autoimmune diseases, sickle cell anemia, radiation therapy, pyoderma gangrenosum, and other rare diseases.  

Ulcers of atypical origin are often only reported in the literature as small case studies or series with the incidence ranging from 2.1% to 23% and treatment varying.^5-7 Often, atypical ulcers are halted in the inflammatory state and do not have the ability to progress to proliferation, maturation and, ultimately, healing.^8-12 Treatment for atypical ulcers requires a multidisciplinary care team including plastic, podiatric, and vascular surgeons; rheumatologists; dermatologists; infectious disease specialists; internal medicine specialists; nutritionists; and others. A proper etiologic diagnosis is extremely important as it guides appropriate treatment and potential medical management of the patient.  

Patients with underlying autoimmune disease require medical optimization of their disease to help balance immunosuppression and ulcer healing.^11,12 Patients with rheumatoid arthritis (RA) are often on immunosuppressive medication such as anti-tumor necrosis factor alpha (anti-TNFα) or disease modifying antirheumatic drugs (DMARD).¹⁰ These medications can alter the typical ulcer healing process, as well as increase the risk of developing infection.

Due to the inflammatory state of many of these atypical ulcers, definitive tissue and ulcer coverage is not always possible on the first visit to the operating room. Cellular- and tissue-based products have been introduced and are used to achieve temporary coverage of the ulcer while waiting for medical and ulcer optimization. Bovine collagen-glycosaminoglycan matrix (BCGM) (Integra Dermal Regeneration Matrix, Integra LifeSciences Corp, Plainsboro, NJ) is an acellular, bilayered, dermoconductive bioengineered alternative tissue. It serves as a scaffold for vascular ingrowth and population of the matrix with host fibroblasts.^13,14 The BCGM is often used to achieve coverage to optimize the wound bed prior to a split-thickness skin graft (STSG) and helps reduce scar contracture.^15-21 The authors have extensive experience with this BCGM for all types of ulcers.^22-24 From their experience, they also believe it has some benefit in pain reduction, especially in this patient population where pain is more severe. 

The primary purpose of this study was to evaluate the use of the BCGM on atypical lower extremity ulcers.  From observations, the authors predict the BCGM will significantly help with ulcer healing and also help with pain reduction. A retrospective chart review was performed to determine the number of ulcers that healed, number of ulcers that received a STSG, time to STSG, number of BCGM applications, and complications.  

This study was approved by the Biomedical Institutional Review Board of Georgetown University, Washington, DC). The study site is a tertiary referral center for limb salvage and ulcer care (Georgetown University Hospital, Center for Ulcer Healing, Washington, DC) that treats all types of chronic ulcers in a high volume of patients. The aim of the study was to evaluate the use of BCGM on atypical lower extremity ulcers. All patients who had application of the BCGM were identified using Current Procedural Terminology (CPT) codes (15271-15278), between January 2009 and October 2014 on an atypical ulcer. An atypical ulcer was defined as one associated with a systemic autoimmune disease (ie, RA, systemic sclerosis, vasculitis, or systemic lupus erythematosus), sickle cell anemia, radiation therapy, coagulopathy, or other cause deemed atypical by the investigator. A Patient Data Request Search through the university identified all the patients who had the above CPT codes associated with at least 1 of the following International Classification of Diseases, Ninth Revision codes²⁵: 135.0, 255.0, 273.2, 282.41, 282.42, 282.60, 282.63, 282.64, 282.68, 282.69, 286.6, 286.9, 425.8, 446.29, 447.6, 517.8, 558.9, 686.00, 686.01, 686.09, 686.8, 692.71, 692.82, 695.2, 696.0, 701.3, 710.0, 710.1, 710.2, 710.3, 710.4, 710.8, 710.9, 714.0, 714.3, 714.8, 714.9, 720.0, 728.9, and 909.2.  

Patients were excluded from the study if the primary etiology of the ulcer was from diabetes, peripheral vascular disease, venous insufficiency, or trauma. In addition, patients were excluded if their ulcer was not located on the lower extremity or the CPT code corresponded to application of a graft other than BCGM. Office notes, hospital records, and operative reports were analyzed. Data collected included age, sex, body mass index (BMI), comorbidities, etiology and location of the ulcer, immune-modulating medications, date of BCGM application, and ulcer cultures. Additionally, the following outcomes were evaluated: ulcer healing or closure, application of a STSG, pain scores (using a 0–10 numerical rating scale) before and after application of the BCGM, complications (ie, infection or dehiscence), or readmissions due to the ulcer. All data was collected and recorded by 2 of the authors (Garwood and Matai).   

Intervention
Prior to surgical intervention all ulcers had been treated conservatively by standard of care wound treatments including a variety of topical modalities, offloading, compression therapy, and antibiotics as needed. All surgical procedures and office visits were performed by 4 of the authors (Kim, Steinberg, Evans, and Attinger). All ulcers in the study were excisionally debrided in the operating room. Debridement included removal of all nonviable soft tissues and bone with the use of a scalpel, scissors, rongeur, curette, or hydrosurgery. Nonviable tissue included fibrotic or necrotic tissue. Debridements were performed until a healthy, bleeding ulcer base and perimeter were obtained. After debridement, the ulcers were pulse lavaged with 3000 mL of normal saline and hemostasis was obtained. The BCGM was then applied to the ulcer bed and secured with staples, prolene suture, or monocryl suture. The ulcer was then dressed, typically with a nonadherent, bolster dressing and triple-layer compression. 

Data was analyzed using descriptive statistics and a paired sample t test was performed.   

Thirty-eight patients with 71 ulcers met the eligibility criteria. The demographics and comorbidities were collected and analyzed (Table 1). Of note, the majority of patients (22, 57.9%) were female. The mean age was 61.6 years, and the mean BMI was 26.7, which is in the overweight category. Ulcer characteristics showed the mean size of the ulcer was 49.5 cm² ± 71.6 cm² at the time of the BCGM application (Table 2). The majority of the ulcers had an underlying etiology of RA, sickle cell anemia, or coagulopathy. Thirty (42.3%) ulcers were located on the ankle and 26 (36.6%) on the leg (Table 2). Patients who were included had a minimum of 1 ulcer and a maximum of 5.

Throughout the course of ulcer treatment some patients received adjunctive therapy in addition to surgical treatment of their ulcer.  Twenty (52.6%) patients were on immune modulators including prednisone, methylprednisolone, hydroxychloroquine, methotrexate, etanercept, abatacept, rituximab, hydroxyurea, immunoglobulin, pentoxifylline, and ruxolitinib. Seven (18.4%) patients received low-frequency ultrasound therapy with saline mist (MIST Ultrasound Healing Therapy, Alliqua BioMedical, Yardley, PA) during the course of the study, and 6 (15.8%) patients received hyperbaric oxygen therapy.  

Pain was assessed and recorded by the clinical staff on the preoperative office visit prior to application of BCGM and on the first postoperative visit (Table 3). It was recorded using a scale from 0 to 10 with 0 being no pain and 10 being the worst pain imaginable. When patients with a preoperative pain of “0” were excluded, there was a mean improvement in pain of 2.5 from preoperative to postoperative, and this was found to be statistically significant (P = 0.0086).  

Ulcer outcomes were analyzed, and the mean number of days of follow-up was 269.2 days (range, 33–795 days) (Table 4). Of note, 30 (42.3%) ulcers in the study healed at a mean of 220.9 days (range, 70–566 days) or 7.8 months. Twenty-six (36.6%) of the ulcers had received a STSG after application of the BCGM at a mean of 77.1 days (range, 15–271 days).  Of the 26 ulcers that received STSG, 17 (65.4%) healed. Figure 1 demonstrates a 36-year-old female with a sickle cell ulcer on her lateral ankle, who achieved complete healing of her ulcer after application of the BCGM and STSG. Fourteen (36.8%) patients had a minor complication of local infection or graft dehiscence during the follow-up period. The bacteria present in the ulcers, through qualitative culture methods prior to debridement and application of BCGM, was collected (Table 5). No growth on the ulcer culture was seen in 27 (38.0%) of the ulcers, and the most common bacteria noted were Staphylococcus aureus, Pseudomonas aeruginosa, and Proteus miribilis.  

Although the incidence can vary, clinicians must have a high suspicion for an atypical etiology of an ulcer especially if it remains nonhealing despite appropriate care and common ulcer etiologies. A study in 2011 by Shanmugam et al⁵ showed that approximately 23% of patients presenting to the authors’ tertiary ulcer care center had an associated immune disease that contributed to the etiology of their ulcer. This study also found that in patients with an immune disease, ulcers are larger than those on patients without an immune disease. Additionally, in patients with an immune disease, ulcers are associated with worse outcomes after STSG than ulcers in patients without an immune disease. Other studies^6,7 have shown a prevalence ranging from 2.1% to 6.6%.  A study⁷ from 2007 reported that 2.1% of ulcers presenting to a vascular clinic had an origin other than venous or arterial disease with etiologies including vasculitis, neoplasia, metabolic disorders, pyoderma gangrenosum, calciphylaxis, and other rare conditions.    

Healing was seen in 42.3% of ulcers in the current study. There was also a 65.4% healing rate in ulcers that received STSG after BCGM. This shows BCGM alone facilitates healing but may be even more beneficial when done in combination with STSG. This is a higher healing rate than has been reported in several studies^10,26,27 looking at ulcer healing associated with specific disease states. Healing rates have been noticeably low in complicated ulcers associated with RA and have been reported to be only 31% at almost 2 years follow-up.¹⁰ Wood et al²⁶ reported that 4 of 6 (67%) ulcers healed with application of a STSG for rheumatic ulcers. One study²⁷ reported the use of a collagen, oxidized cellulose dressing (PROMOGRAN Matrix Wound Dressing, KCI, An Acelity Company, San Antonio, TX) on patients with RA who had active pyoderma gangrenosum ulcers and reported 2 patients had healed completely and 2 others had a significant reduction in ulcer size.²⁷  

Other atypical ulcer types have similar challenges related to their unique etiologies. Radiation therapy, for example, can significantly affect ulcer healing by causing increased inflammatory responses, impaired ulcer strength, hypoxia, and lack of control of the other phases of ulcer healing.²⁸ In patients with sickle cell anemia, causes of ulcers can include venous incompetence, mechanical obstruction by sickled red blood cells, excessive vasoconstriction, thrombosis, anemia, and impaired endothelial function.^29,30 Coagulopathy associated with chronic ulcers is due to the evident alterations in coagulation that affect the phases of ulcer healing, most notably hemostasis.³¹ These examples of atypical ulcers demonstrate that various factors are at play and must be considered in surgical and medical treatment plans.

Many of these ulcer types require a multifaceted approach to treatment including various medical therapies to control the patient’s disease state. This includes the addition of immunosuppressive therapy or anticoagulation therapy in addition to standard ulcer management. It is not always possible to completely control inflammation and ulceration through management of the underlying disease state and thus surgical options and management of the ulcers are needed.

A significant reduction in ulcer pain was seen in the present study when analyzing patients who were experiencing ulcer pain prior to surgery. The reason for pain reduction with the use of the BCGM is not clear, but there are several potential explanations. It has been theorized that the BCGM suppresses inflammation including pain, periulcer erythema, and edema.³² The inflammation pathway is never activated in the presence of the BCGM due to the lack of platelet adhesion. Similarly, the body does not produce a defense response against the BCGM because of the acellular properties and similarity to normal tissue. The chondroitin sulfate contained within the matrix may play a significant role in the anti-inflammatory properties as well, and this is already well known for osteoarthritis.^33-35 The bilayer matrix also serves to protect the ulcer from potential causes of inflammation including biofilm or external injury.³² Due to its regenerative properties compared to other products, there is no contracture or scar tissue formation, which may also contribute to less pain during healing. It is the combination of these effects that could explain the reason for pain reduction as well as healing potential with application of BCGM. It cannot be excluded from theory that some of the pain reduction in this study may have been from surgical debridement or elimination of the biofilm. 

Currently there are no major studies looking at the association between pain reduction and the use of BCGM, but there are a few case studies that mention the benefit. A study by Moyer et al³⁶ evaluated the treatment of chronic, painful burns. They excised the ulcers, applied BCGM, and then performed a STSG 3 weeks later. Complete reduction in scar pain was seen in 33% of patients; all patients had reduction of symptoms postoperatively, and there was a significant reduction in the amount of narcotics used per day.³⁶ Similar to the authors’ patient population, the reduction of pain may have been associated with the excision of the painful ulcer itself, the application of the BCGM, or the eventual closure of the ulcer.

Twenty-seven (38%) ulcers in this study had no bacterial growth on predebridement ulcer cultures. This is an interesting finding as it demonstrates that many of the ulcers were not infected. This confirms the chronic nature and nonhealing characteristics of the ulcers were not due to bacterial growth or infection in this subset, but were more likely due to the patients’ underlying disease states. A wide variety of organisms were found in the ulcers that had positive ulcer cultures. The organisms identified were likely contributing to a biofilm and thus also contributing to the chronic nature of the ulcers. It has been demonstrated that biofilms have prolonged the ability of an ulcer to heal, unless adequately managed with techniques such as surgical debridement, in the current study.^37,38  

This study presents several limitations including its retrospective design and reliance on medical records. The accuracy of data collected relies on proper documentation at the time of each patient encounter.  Another limitation is the wide variety of ulcers included in the data. This study looked at all atypical ulcer types and did not determine if any ulcer type had a better response than another. It was also not determined how well the patients’ comorbidities were medically managed and if this had any impact on ulcer healing. Additionally, there was no standard set of criteria the clinicians used to determine when an ulcer would receive the BCGM. Many patients also had adjunctive therapy such as hyperbaric oxygen and low-frequency ultrasound with saline mist, which could have confounded the results, as the treatments were administered at the clinical discretion of the surgeon based on ulcer type, quality, previous treatments, medical management, presence or absence of infection, and chronic state. Other potential confounding factors assessed include treatment with oral or intravenous antibiotics or additional standard of care treatment modalities.

Bovine collagen-glycosaminoglycan matrix has been successfully used on burn injuries, traumatic ulcers, diabetic ulcers, and other ulcers with common etiologies.^22,39-42 This study demonstrates the use of BCGM on recalcitrant lower extremity ulcers with atypical etiologies, where it has been shown to decrease ulcer pain, serve as a scaffold for ulcer healing, and serve to prepare the ulcer bed for skin grafting. The BCGM should be considered for use when conservative therapies are failing. It was successful in ulcer healing when used alone, but may be even more beneficial when used in combination with STSG. Although the BCGM has proved a positive addition to the ulcer care regimen, more robust and prospective studies are needed with a larger patient population to better evaluate the use of BCGM on these challenging ulcers.  

The authors would like to acknowledge Anagha Kumar, MS for his editorial and statistical analysis assistance.

Affiliations: MedStar Georgetown University Hospital, Washington, DC; Department of Plastic Surgery, Georgetown University School of Medicine, Center for Wound Healing and Hyperbaric Medicine, Washington, DC; MedStar Washington Hospital Center Podiatric Residency, Washington, DC; and Codirector, Center for Wound Healing and Hyperbaric Medicine, MedStar Georgetown University Hospital, Washington, DC 

Correspondence:
Caitlin S. Garwood, DPM, AACFAS
Diabetic Limb Salvage Fellow
MedStar Georgetown University Hospital
3800 Reservoir Rd, NW
Bldng 1, Center for Wound Healing 
Washington, DC
Caitlin.garwood@gmail.com 

Disclosure: Drs. Kim, Steinberg, and Attinger are consultants for Integra LifeSciences Corp. This study received no financial assistance.