Wound Healing Outcomes Following Treatment With Synthetic Hybrid-Scale Fiber Matrix After Resection of Soft Tissue Tumors or Infections

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Bone and soft tissue surgical resections are performed to treat various skin, bone, or connective tissue disorders.^1,2 Depending on the severity and location of the underlying disease, these resections can result in large open wounds which may involve muscle, fascia, bone, or joint capsules^.2-4 These wounds are often challenging to treat, and prolonged healing times can lead to further complications, including infection, amputation, and additional surgical procedures.⁵ Connective tissue cancers and bone cancers, known as sarcomas, and necrotizing soft tissue infections are 2 common etiologies that are managed via radical or wide excision of the affected tissue.^1-6

These resections are associated with a high rate of complications, including infection, dehiscence, necrosis, and hematoma.^1,5,6 Surgical resection of cutaneous and soft tissue infections due to mycobacterium are especially associated with poor aesthetic outcomes, such as hypertrophic scarring and disfigurement at the site of the infection.⁶ While skin grafting is often utilized to provide rapid coverage and a biologic barrier for these open wounds,⁷ this approach is not without limitations. Skin grafts require a well-prepared wound bed with healthy granulation tissue in order to successfully incorporate.⁷ In the instance of sarcoma and mycobacterium-infected tissue resections, the resulting wound can be complicated by exposed bone, joint capsule, or tendon, and is often not immediately prepared for skin grafting. NPWT has been used successfully to stimulate granulation tissue formation within deep wounds in preparation for skin grafting; however, it is limited in its ability to stimulate this over exposed structures within the wound bed.⁸ For granulation tissue to successfully cover these exposed structures, it must grow in horizontally as opposed to vertically.⁸ Use of NPWT in deep wounds with exposed structure may elicit more coverage over these structures when used in combination with wound healing matrices designed to encourage cellular migration.⁸

The healing process following large resections of tumors or infected tissues can be complex. Considering the high rate of complication following these procedures,^1,5,6 the inability to immediately skin graft due to exposed structures within the wound bed,⁷ and NPWT limitations over structures,⁸ new treatment methods should be considered to address the needs of this patient population. An SHSFM (Restrata; Acera Surgical Inc.) may provide a viable solution to the challenges currently associated with these procedures. The fully synthetic matrix is composed of 2 bio-resorbable polymers, polyglactin 910 and polydioxanone, which are utilized in many clinical applications such as dura substitutes, resorbable sutures, and orthopedic implants.⁹ These synthetic polymers offer ideal resorption rates that match those of tissue ingrowth, providing a controlled transition from the matrix to regenerated tissue.^9,10 Within the SHSFM, these polymers have been electrospun and engineered to mimic human extracellular matrix in both size and structure, thereby encouraging cellular ingrowth and neovascularization.^9,10 The SHSFM has shown promising outcomes in the treatment of surgical wounds and can be utilized either to prepare a wound bed for skin grafting or advance a wound to full reepithelialization.^7,11

The purpose of this retrospective case series was to determine the efficacy of an SHSFM in the treatment of complex surgical wounds resulting from bone or soft tissue resections.

A retrospective, single-investigator, single institutional study was conducted evaluating the use of the SHSFM in the treatment of complex surgical wounds resulting from bone or soft tissue mass resections. Data were collected by a review of patient medical charts. The medical charts examined included patients who underwent a resection of either sarcoma or infected tissue performed by a single orthopedic oncologist. Sarcoma and infected tissue procedures were selected based on the treating physician's patient population and clinical expertise. Patients within this population who had received a single application of the SHSFM in the operating room immediately following the resection were included in this review. Given the retrospective nature of the study and lack of identifiable patient information being collected, the study was deemed exempt per local institutional review board.

To be included in the review, patients must have been 18 years of age or older and treated with the SHSFM in the operating room following surgical resection of bone or soft tissue to manage either sarcoma or bacterial infection. Treatment with an SHSFM was selected in order to stimulate granulation tissue formation over exposed structures in preparation for successful skin grafting or encourage secondary intention healing in a population with large defects that were not candidates for primary closure. Both pre-meshed and solid SHSFM sheets were utilized. When solid sheets were selected, they were either manually fenestrated with a blade or pre-hydrated with saline and processed through a skin-graft mesher in the operating room. The SHSFM was then applied in full contact with the wound bed and edges and secured with resorbable sutures. Various wound dressing methods were utilized depending on the patient, including wound vacs, non-adherent cellulose acetate dressings, bacteriostatic foam dressings, gauze wrap, cast padding, petrolatum dressings, or abdominal pads. In 2 cases, the SHSFM was utilized in conjunction with urinary bladder matrix. In 1 case, the SHSFM was utilized in conjunction with a placental tissue allograft.

Medical records were examined for wound healing progress. Time to definitive closure was documented and defined by 100% reepithelialization of the surgical wound or by sufficient regranulation of the surgical wound bed in preparation for split-thickness skin grafting, plus confirmation of successful skin graft incorporation at the resection site. Additionally, demographic information, comorbidities, wound sizes, and any complications were collected and documented during the chart review. Images of healed wounds were assessed for scar quality using the VSS when available.

A total of 10 patients met the inclusion criteria and were analyzed. The patient population was 40% female and 60% male. The average patient age was 53.9 ± 12.6 years. Comorbidities included mycobacterium infection, seizure disorders, hypertension, renal cell carcinoma, gastroesophageal reflux disease, prior sarcomas, peripheral vascular disease, and clotting disorder.

Overall, 7 out of 10 wounds went on to achieve complete closure. The 3 wounds that did not have documented closure were a result of patient death from underlying cancer (n = 1) and completion of post-graft follow-up out of state with no access to local medical records (n = 2). One patient who was lost to follow-up did confirm healing via telephone call; however, there were no available medical records or images to confirm. The etiologies of the resections were either mycobacterium (40%) or tumorous (60%), including renal cell carcinoma metastasis, myxofibrosarcoma, and others. The initial post-resection starting wound size was 195.1 ± 190.3 cm². Out of the 10 patients included, 40% of patients received skin grafts and 60% reepithelialized via secondary intention.

For the patients who underwent skin graft reconstruction following use of the SHSFM, the average time to skin grafting was 59.3 ± 20.5 days. Considering that these resections were tumorous or infectious in origin, the treating physician elected to delay definitive closure with a skin graft until final pathology reports from the initial resection were made available to evaluate the possibility of local recurrence. The time to complete wound closure through either complete graft incorporation or secondary intention reepithelialization was 119.1 ± 32.6 days when reported.

One minor complication of hyper-granulation tissue formation was reported in one patient but was successfully treated with silver nitrate. This patient went on to heal by secondary intention with no further complications. There were no incidences of post-surgical infection. The average VSS score was 3.3 ± 1.9 when assessed. Individual wound outcomes can be found in the Table. Representative wound healing images can be found in Figures 1, 2, and 3, which were selected to represent varying wound etiologies and closure approaches.

The current retrospective study demonstrates positive preliminary results seen when utilizing the SHSFM in post-resection surgical wounds of varying origins. Prior studies assessing the success of standard-of-care graft incorporation in sarcoma resection wounds demonstrated a graft incorporation rate of 67.5%, with 5 out of 8 grafts partially lost.¹² The majority of those grafts (7 of 8) were applied directly to the muscle stump and tendon.¹² In the current study, the SHSFM was utilized to successfully granulate tissue over exposed structures prior to skin grafting, which is critical to ensuring healthy graft incorporation.⁷ The SHSFM was also utilized to reepithelialize post-resection surgical wounds by promoting secondary intention healing. Use of the SHSFM in this manner eliminated the need for skin grafting procedures. This approach may be beneficial for patients who are either unwilling to undergo additionally surgery or who may be at increased risk of either donor site morbidity or graft failure.^13,14

Wide resection of sarcoma and soft tissue infections are associated with a high rate of surgical site infections postoperatively,¹⁵ with surgical site infections reported to occur at rates as high as 18.4%.¹⁵ The presence of an open wound is one variable that increases the risk of postoperative infection. In the current retrospective case series, no patients developed postoperative infections, despite being at high risk for these due to history of mycobacterium infections, cancer, and/or presence of a large, open wound.¹⁵ The degradation byproducts of the 2 bioresorbable polymers that comprise the SHSFM have been known to demonstrate antimicrobial effects. Additionally, nonhealing wounds tend to be more alkaline, while healthy, intact skin is naturally acidic.⁹ The degradation byproducts of the synthetic polymers within the matrix, such as lactic acid and polylactic acid, introduce an acidic environment in the wound bed and may support wound healing by restoring normal pH to damaged tissue.⁹ This effect may contribute to the absence of post-surgical infections observed in the current case series and warrants further investigation.

The SHSFM demonstrated positive outcomes when utilized to treat wounds via secondary intention healing in this retrospective case series. Secondary intention healing of large defects can often result in scarring, intense inflammatory response, hyper-granulation tissue formation, and wound contracture.¹⁶ In the current study, average VSS score was 3.4 at closure for patients who healed via secondary intention. For the 5 patients in whom the scar was assessed, the vascularity was either pink or normal, pigmentation was normal, and no contracture was reported. The engineered design of the matrix is similar to human extracellular matrix, and through topographical cues can activate fibroblasts for scar remodeling, minimize inflammation, and encourage the natural wound healing process.^9,10 Prior retrospective clinical case studies of the SHSFM in post-Mohs micrographic surgery wounds and second-degree burns have demonstrated minimal scarification and return of skin pigmentation.^17,18

As a retrospective clinical case series with a small number of patients, this study possesses some limitations. Data collection was limited to the availability of medical records, and there was no standardized treatment protocol. As a single-arm study, there was no direct comparison to standard-of-care treatment or other advanced treatment modalities. Three patients in this retrospective case series were also treated with xenograft and allograft matrices, which complicates the ability to isolate the effect of the SHSFM in those 3 cases. Prospective comparative studies should be considered in the future to further elucidate the benefits of SHSFM in the management of large soft tissue defects resulting from surgical resections.

In the current study, an SHSFM was utilized to manage large soft tissue defects resulting from wide resection of tumors or infections and demonstrated its ability to be used successfully either alone or with other advanced wound therapies. The findings in this retrospective clinical case series support the use of SHSFM in wide resection surgical wounds by either 1) improving graft incorporation via supporting healthy granulation tissue formation over exposed structures, or 2) by reepithelializing large wounds without the need for skin grafting procedures.

Authors: Bennie Lindeque, MD, PhD; and Daniel Moon, MD

Affiliation: UCHealth Orthopedics Clinic, Anschutz, CO 

Disclosure: Acera Surgical, Inc. provided financial support for this study, including study coordinator hours, principal investigator oversight, and start-up and close-out fees. 

Correspondence: Bennie Lindeque, MD, PhD; UCHealth Medical Group, 1635 Aurora Court Anschutz Outpatient Pavilion, 4th floor Aurora, CO 80045; bennie.lindeque@cuanschutz.edu

Manuscript Accepted: December 19, 2023