Use of a Synthetic Hybrid-scale Fiber Matrix in the Management of Chronic and Complex Wounds: A Retrospective Case Series

Complex wounds have various etiologies, including disease, infection, and trauma. The term complex wounds is associated with wounds that are chronic or that occur in patients with compromised vascularity or other comorbidities that negatively affect wound healing.¹ Patients with chronic or complex wounds often experience reduced mobility and social isolation, which negatively affect their quality of life.² The cost of caring for these wounds in the United States is estimated to be over $28 billion annually.³ With an aging population, increasing rates of diabetes and obesity, and approximately 40 million to 50 million major surgeries performed each year in the United States, it is vital to find novel solutions to manage wounds that arise as a result of these factors.^4,5

Use of SHSFM is gaining popularity in the management of complex and chronic wounds. The matrix is engineered to mimic the structure and size of native human extracellular matrix, which allows for cellular infiltration while resorbing via hydrolysis at the rate of tissue ingrowth and reepithelialization.⁶ The synthetic nature of the matrix allows for excellent biocompatibility and reduces the risk of inflammation and infection associated with the use of biologic materials.^6,7

Prior studies have shown positive results with the SHSFM, with wound healing rates between 75% and 85% in venous leg ulcers, DFUs, and other lower extremity wounds at 12-week follow-up.^8,9 The current retrospective case series assessed the efficacy of the SHSFM in the management of complex wounds of various etiologies in patients with various comorbidities.

This retrospective case series assessed the use of the SHSFM (Restrata; Acera Surgical, Inc) for the management of complex wounds of varying etiologies. Data were collected via a retrospective review of patient charts. Patients who received at least 1 application of the SHSFM between September 2019 and December 2021 were included in the study. 

Prior to application, the SHSFM was soaked in saline for 1 minute. The matrix was either applied meshed (when available), or it was fenestrated with a scalpel prior to application. The matrix was cut to the wound surface area and then applied either in the operating room or at the bedside, depending on clinical assessment of the wound and the patient. After the matrix was applied to the wound bed, a nonadherent primary dressing was applied. Depending on the wound, an antimicrobial or silver dressing was applied in conjunction with the matrix. In some cases, depending on wound depth, NPWT was used in conjunction with the matrix to stimulate granulation tissue formation.  

Wound healing was assessed at follow-up visits, and the SHSFM was reapplied as deemed clinically appropriate. At the wound assessment visits, the treating physician evaluated the amount of matrix that remained in the wound bed. If matrix breakdown was greater than 50%, the SHSFM was reapplied. However, if matrix breakdown was less than 50% and the treating physician observed a 10% wound closure rate per week, no additional applications were necessary to facilitate wound closure. 

Based on wound type and clinical assessment, either the wound was treated with the SHSFM until closure was achieved, or the matrix was used to promote granulation in the wound bed in preparation for skin grafting. Skin grafting was not the end goal for all patients treated with the SHSFM, and several patients were treated with the matrix until complete reepithelialization via secondary intention occurred. Prior to assessing if a skin graft should be considered for a wound, the treating physician determined whether the wound would heal in 3 to 4 weeks with the SHSFM. If the physician determined that this time frame was not feasible for complete closure with the matrix, the wound was considered for skin grafting, and the matrix was used to encourage regranulation of the wound in preparation for skin grafting. 

Eighteen patients with a total of 28 wounds were included in the study (Table 1). Wounds were located on the foot, lower and upper extremities, and other anatomic areas, including the groin, back, and sacrum. Wound etiologies varied, including 6 ulcers of venous, diabetic, and pressure origins; 6 surgical dehiscence wounds; 4 traumatic wounds; 9 necrotizing soft tissue infections (post-debridement); and 3 other wounds, including lymphedema and hidradenitis after resection. The average patient age was 59.2 years ± 11.4 standard deviation, and the average initial wound surface area was 43.4 cm² ± 52.7. Patients had multiple comorbidities, including type 2 diabetes mellitus, peripheral vascular disease, hypertension, dyslipidemia, obesity, end-stage renal disease, anxiety, depression, and neuropathy.

Overall, 89% of wounds (n = 25) achieved complete closure at an average of 196 days ± 146.7 (Table 2). The 3 wounds that did not heal were lost to follow-up. The number of SHSFM applications per wound ranged from 1 to 11. Unsuccessful previous treatment of these wounds included collagen, NPWT, antibiotic bioresorbable polymeric matrices, and various antibacterial dressings, in addition to control of comorbidities and standard wound care practices such as control of edema and blood glucoses.

Case 1

A 40-year-old female presented to the treating physician after undergoing surgical excision of a ganglion cyst and hematoma evacuation. Dehiscence occurred after the procedure, and the patient was seen by the treating physician to manage wound healing. The initial wound presented with eschar, which was trimmed by the patient’s podiatrist 1 week after presentation to the wound clinic (Figure 1A). The patient returned to the wound clinic 1 month later and underwent weekly sharp debridement and treatment with antibacterial foam dressings for 2 weeks. At that time, the wound measured 9 cm² and treatment with the SHSFM was initiated (Figure 1B). The patient underwent 4 applications of the SHSFM to the wound bed over the next 3 months (Figure 1C-E). The matrix was applied approximately every 2 weeks, based on the rate of resorption of the matrix into the wound bed. Before each application, the physician debrided the wound and used a nonadherent cellulose primary dressing and an absorbent foam secondary dressing. The wound was fully reepithelialized 73 days after the initial application of the SHSFM (Figure 1F). After reepithelialization, steroid injections were administered into the scar contracture. 

Six months after initial wound closure was achieved, the patient had a recurrence of the ganglion cyst. Two cysts had developed on the right ankle and right dorsal foot, both of which required surgical excision. The initial wounds after surgical excision measured 2.5 cm² on the right ankle and 1 cm² on the right dorsal foot. Owing to the patient’s history of poor wound healing, treatment with the SHSFM was initiated 1 week after excision. At the follow-up visit in the wound clinic 2 weeks after initial application of the SHSFM (Figure 2A), the wounds were debrided and measured 2.5 cm² on the right ankle and 1 cm² on the right dorsal foot. Because the SHSFM had resorbed into the wound bed the matrix was reapplied, and a nonadherent cellulose primary dressing and an absorbent foam secondary dressing were placed. The patient was seen in the clinic 3 weeks after the initial application of the SHSFM (Figure 2B). The matrix remained in place, so dressings were changed and the SHSFM was left in the wound bed to continue to resorb. Five weeks after initial treatment with the SHSFM, the second application had fully resorbed. The wounds were debrided and measured 1.5 cm² on the right ankle and 0.3 cm² on the right dorsal foot (Figure 2C). The SHSFM was reapplied to the wound beds and the wounds were dressed. The patient returned to the clinic 7 weeks after initial application for a fourth application of the SHSFM (Figure 2D). Nine weeks after the initial application of the matrix, both wounds were fully reepithelialized (Figure 2E). Throughout the treatment course, the SHSFM was applied approximately every 2 weeks, based on the rate of resorption of the matrix into the wound bed. 

Case 2

A 43-year-old female with a history of hyperlipidemia, hypertension, peripheral artery disease, and uncontrolled diabetes, as well as a history of osteomyelitis of both feet necessitating bilateral transmetatarsal amputations, presented with a necrotizing soft tissue infection of the left upper posterior thigh (Figure 3A). The wound was surgically debrided, resulting in an initial wound size of 240 cm² (Figure 3B). The SHSFM was meshed, applied to the wound bed during the procedure, and stapled in place (Figure 3C). The wound was dressed with petrolatum-based fine mesh gauze containing 3% bismuth tribromophenate and an absorbent secondary dressing that was changed daily. The treating physician observed the wound 11 days later, at which time the SHSFM remained adherent to the wound bed and was left in place to continue to resorb. A petrolatum-based fine mesh gauze containing 3% bismuth tribromophenate and an absorbent secondary dressing were applied to the wound. Three weeks after the initial application of the SHSFM, the matrix had completely resorbed and significant regranulation of the wound bed was observed (Figure 3D). The wound was debrided and dressed as before. Continued wound healing was observed 5 weeks after initial application of the matrix, and reepithelialization was observed at the wound edges (Figure 3E).

Wound healing was assessed 9 weeks after initial application of the matrix. Continued regranulation of the wound bed was observed, along with further reepithelialization around the distal edges of the wound. The wound was debrided and measured 3.3 cm × 11 cm. The wound was dressed using petrolatum-based fine mesh gauze containing 3% bismuth tribromophenate and an absorbent secondary dressing. At 11-week follow-up, further reepithelialization of the wound’s outer edges was noted, and the wound measured 1.5 cm × 8.7 cm. Continued wound reepithelialization was noted at 13-week follow-up (Figure 3F). After debridement, the wound area measured 13.1 cm². At 15-week follow-up, the wound area measured 4.2 cm². At the final visit at 18 weeks, complete reepithelialization of the wound was observed. Complete closure was achieved 131 days after 1 application of the SHSFM (Figure 3G). 

Chronic and complex wounds can be painful and emotionally burdensome, and they can limit patients’ daily activities.³ New wound therapies are needed to improve patient quality of life and reduce the financial burden that long-term wounds often place on patients and the health care system alike.^1-3,10 The use of an SHSFM, as demonstrated in the current retrospective case series, shows promise in treating wounds of varying etiologies in various anatomic locations. 

The positive outcomes in this case series parallel those achieved with the SHSFM in previous studies.^3,8 Barton and Abicht³ reported complete healing in 96% of wounds at an average of 96.1 days in a case series in which the SHSFM was used in the treatment of a variety of lower extremity wounds, including venous leg ulcers, DFUs, and transmetatarsal amputations. Regulski and MacEwan⁸ observed similar results in a case series of 82 lower extremity wounds, including venous leg ulcers, DFUs, and others. These wounds had been open for at least 4 weeks prior to first application of the SHSFM, and 85% of the treated wounds demonstrated complete closure by 12 weeks.

In the current case series, the average time to healing was 196 days ± 146.7, likely due in part to the large initial size of the wounds (average, 43.4 cm² ± 52.7). In the Barton and Abicht³ case series of lower extremity wounds, the average initial wound size was 18.7 cm² ± 18.8 and wound healing was achieved in an average of 96.1 days ± 53.8. The initial wound size in that study was approximately 57% smaller than the starting wound size in the current study. The ratio of wound size to time to healing is proportionally consistent between these 2 studies. The large standard deviation range observed in this retrospective case series is likely owing to the varied patient population. Adult patients of all ages and with a variety of wound sizes, comorbidities, and wound etiologies were assessed, and the wide range of healing times reflected patient status and wound etiology. In future studies, wound etiologies and patient populations should be isolated and assessed to determine more specific responses to the SHSFM. Twelve-week healing rates are often reported in studies of DFUs. However, given the large range of etiologies, severity of comorbidities, and large wound surface area (43.4 cm² ± 52.7 in the current study vs 2.1 cm² ± 1.46 and 3.1 cm² ± 3.58 in prior DFU studies¹¹), a 12-week time to healing was not a realistic goal for the patients in the current study. 

The patient population in this retrospective case review included patients with multiple comorbidities, including those that negatively affect wound healing such as peripheral vascular disease, diabetes, obesity, and end-stage renal disease.^1,12 The SHSFM has demonstrated positive results in this complex patient population in both the current retrospective case series and prior studies. A prospective study of DFUs managed with the synthetic matrix involved patients with multiple comorbidities, including cardiovascular disease, diabetes, and obesity.⁹ By 12 weeks, 75% of wounds in that study achieved closure, a marked improvement compared with the standard of care healing rate of 18% to 26% in this population reported in other studies. Tucker¹³ demonstrated efficacy with the synthetic matrix in conjunction with other advanced therapies to achieve closure of wounds resulting from amputation. In that retrospective case series, the patient population had complex amputation wounds in addition to multiple severe comorbidities such as type 2 diabetes, obesity, kidney disease, and heart failure. Overall, 7 of 9 patients included in that case series achieved complete closure at an average of 135.6 days ± 49.1 and did not require further amputation. 

The promising results observed in the current study are likely due in part to the engineered design of the SHSFM. The matrix is composed of 2 bioresorbable polymers that have been electrospun to mimic native human extracellular matrix.⁶ This engineered design provides a scaffold that encourages cellular ingrowth and proliferation via topographical cues. Through these cues, the matrix encourages cellular infiltration and neovascularization. As the matrix resorbs via hydrolysis, the porosity of the structure increases.⁶ This increase in matrix porosity allows for cellular differentiation and retention, and as the matrix resorbs via hydrolysis, it provides controlled offloading from the matrix to the newly formed tissue.⁶ Depending on the wound, this mechanism of action can be used to achieve the appropriate clinical end point, such as complete closure via reepithelialization or staging to a split-thickness skin graft.¹⁴

This study has limitations. It is a retrospective case series with no control group. Additionally, it was conducted at a single site by a single physician. Wounds of varying etiologies are reported in this case series, and the limited number of each wound etiology makes it challenging to draw conclusions regarding which wounds would benefit most from treatment with the SHSFM. As with all retrospective studies, this case series was also subject to selection and recall bias.¹⁵ Future studies should be considered to further evaluate the positive results noted in the current study, including comparative studies to analyze the cost of treatment of these wounds and review the cost-effectiveness of the SHSFM. 

Overall, treatment with the SHSFM resulted in complete closure of 89% of the complex and chronic wounds described in this case series. These positive clinical results were achieved despite multiple comorbidities, large wound sizes, and varying wound etiologies. The results of this retrospective case series indicate that the SHSFM is safe and can be used to treat wounds of multiple etiologies. This retrospective study also demonstrates that the SHSFM can be used to achieve various clinical goals, be they achieving complete reepithelialization via use of the graft alone, or encouraging regranulation of the wound bed to bridge to a skin graft. These results suggest that the SHSFM should be considered a viable treatment option in the management of chronic and complex wounds.