Augmented Flap Reconstruction of Complex Pressure Ulcers Using Synthetic Hybrid-Scale Fiber Matrix

Flap reconstruction of pressure ulcers offers an important clinical means of decreasing morbidity in both inpatient and outpatient settings. Unfortunately, complication rates following pressure ulcer reconstruction using flap coverage are reportedly high, as patients commonly have multiple risk factors for postoperative dehiscence, hematoma formation, partial or complete flap necrosis, infection, and ulcer recurrence.^1-3 Risk of pressure ulceration in patients with spinal cord injury, the elderly population, and patients who are immobilized due to chronic conditions is significant.⁴ On average, the prevalence of pressure ulcer in patients across various care settings in the United States was reportedly 9%.^4,5 A novel method of managing chronic wounds was developed in which a synthetic hybrid-scale fiber matrix is applied prior to flap reconstruction. A retrospective study reported complete wound closure rates of 85% in diabetic foot ulcers and 91% in venous leg ulcers after 12 weeks when the synthetic hybrid-scale fiber matrix was included in the clinical approach.⁶

The structure of Restrata Wound Matrix (Acera Surgical, Inc) is similar to that of human extracellular matrix (ECM) and supports cell ingrowth, retention, and granulation tissue formation.⁷ This synthetic hybrid-scale fiber matrix is the only flexible, suturable, electrospun matrix for use in encouraging wound healing. The matrix is fabricated by solvent electrospinning polyglactin 910 poly (lactic-co-glycolic acid) (10:90) and polydioxanone, polymers approved by the US Food and Drug Administration, and it has been used in biomedical devices such as resorbable polymers.⁷ The synthetic hybrid-scale fiber matrix was analyzed per International Organization for Standardization-10993 standards, and results confirmed the safety and biocompatibility of the matrix.⁸ The matrix resorbs in 1 to 4 weeks depending on the wound condition and type.^7,9 The degradation products of the synthetic matrix are safe and can be cleared without the risk of biofilm formation.⁷ The matrix is composed of nonwoven, resorbable, synthetic hybrid-scale fibers with a structure and architecture that mimics that of native human ECM. Due to its unique design, the matrix resists enzymatic degradation, persists in the wound bed, has excellent biocompatibility, and supports cellular and/or tissue ingrowth. The unique properties of the synthetic hybrid-scale fiber matrix also offer ease of use, availability for use in both the inpatient and outpatient settings, and clinical versatility with significant logistical advantages over existing amniotic, allogenic, and biologic products.

Electrospun hybrid-scale fibers support cellular ingrowth, retention, and differentiation while directing and enhancing cellular activity. The porosity and progressive resorption of the matrix support continued cellular infiltration, tissue formation, and neovascularization. Prior studies confirmed that the synthetic materials are a unique alternative to allografts and xenografts in supporting wound healing.⁷ The primary objective to include the synthetic hybrid-scale fiber matrix in the treatment approach of pressure ulcers in this case series was to ensure (1) integration to the wound bed prior to flap closure to encourage granulation tissue formation at a later time, and (2) lasting successful wound closure following flap reconstruction.

Data were retrospectively collected via chart review by the treating physician at Nexus Wound Care in Shenandoah, Texas. Data from wound care patients treated with synthetic hybrid-scale fiber matrix between May 2019 and December 2019 were included in the study. Patient eligibility for treatment with the synthetic hybrid-scale fiber matrix was based on wound type, severity, and duration. Inclusion criteria were patients with stage 3 or 4 sacral, ischial, or trochanteric pressure ulcers for whom standard of care was unsuccessful and who required definitive closure between May 2019 and October 2019; no limitation was defined for patient age and sex. Patients with pressure ulcers that required wound debridement and/or primary closure without flap coverage were excluded. The synthetic hybrid-scale fiber matrix was applied to ulcers prior to flap reconstruction, based on physician assessment of wound status. Prior to application, sharp debridement of the wound margins and wound bed was performed. The patients were additionally prepared to accept the matrix via nutrition optimization, offloading of the affected area, and administration of intravenous antibiotics as indicated.

The synthetic hybrid-scale fiber matrix was fenestrated as necessary and then directly applied to the wound bed and secured in place with staples or sutures. Following application of the matrix, a nonadherent dressing was placed over the graft. Subsequently, a foam dressing was placed over the nonadherent dressing, followed by the application of negative pressure wound therapy (NPWT). Dressings were changed every 2 or 3 days prior to flap reconstruction. The synthetic hybrid-scale fiber matrix was left in the wound bed to achieve successful wound closure and complete wound healing following flap closure. The gluteal flap reconstruction technique was selected based on the wound anatomy. A gluteal flap uses gluteal muscle separation from its origin at the sacrum and rotated over the ulcer cavity as 1 tissue and then is inset with stitches. The overlying skin is either separated as a rotational skin flap or advanced with the muscle as a myocutaneous flap. The separation is necessary only when the flap will not properly turn, thus necessitating so-called cutbacks to allow for proper rotation without tension. Data on patient wound and health conditions are provided in the Table (Part 1 and Part 2).

In this retrospective study, patients with pressure ulcers for whom prior wound therapies were unsuccessful and who had various risk factors for postoperative complications were enrolled (Table Part 1 and Part 2). Wounds were managed by applying an appropriately sized synthetic hybrid-scale fiber matrix (covering the wound bed) prior to flap reconstruction. The synthetic hybrid-scale fiber matrix integrated to the wound bed, which encouraged granulation tissue formation in the wound bed; adherence over 3 days to 7 days helped confirm that flap coverage was justified and likely to heal. No complication was reported after application of the wound matrix and after flap closure. The patients were observed for up to 24 weeks and demonstrated continuous interval wound closure and complete healing. Overall, the wound bed preparation with the synthetic hybrid-scale fiber matrix resulted in an outstanding wound closure rate.

Case 1

A 53-year-old male with quadriplegia since 1986 had a left ischial ulcer that was open for 24 months and had not been successfully managed with NPWT (Figure 1A). The synthetic hybrid-scale fiber matrix was applied to the wound bed and allowed to heal for 7 days, after which flap reconstruction was performed (Figure 1B). The wound remained closed 2 weeks and 3 weeks after flap closure (Figure 1C, D). Complete wound healing was achieved within 10 weeks.

Case 2

The patient was a 19-year-old male with neuromyelitis and functional quadriplegia. A left trochanteric pressure ulcer was open for more than 4 months prior to the operation (Figure 2A) and had not been successfully managed with NPWT. After wound bed preparation, synthetic hybrid-scale fiber matrix was applied to improve the quality of new tissue formation (Figure 2B). After 4 days, the flap reconstruction surgery was conducted (Figure 2C, D). The wound completely healed after 9 weeks (Figure 2E, F).

Case 3

A 44-year-old male with incomplete quadriplegia (low cervical nerve injury at C5 and C6) had a pressure ulcer on the right ischial spine persisting for more than 6 months (Figure 3A). The use of topical wound therapies had been unsuccessful. Synthetic wound matrix was stapled to the wound bed to encourage granulation tissue formation (Figure 3B). After 7 days, a skin flap was rotated over the wound (Figure 3C). The wound was assessed at 3-week and 9-week follow-up; after 9 weeks, the wound remained intact and closed without any complication (Figure 3D, E).

Case 4

A 47-year-old female with Hurler syndrome and associated intellectual disability had a chronic stage 4 pressure ulcer on the left trochanteric prominence that was open for more than 6 months (Figure 4A) and had not responded to NPWT or osteomyelitis therapeutics. The wound was debrided (Figure 4B) and a synthetic hybrid-scale fiber matrix applied (Figure 4C). After 5 days, the wound was reconstructed with a fasciocutaneous advancement flap (Figure 4D). The closed wound remained intact, with no signs of dehiscence or infection 6 weeks postoperatively (Figure 4E, F).

Case 5

A 61-year-old male presented with an abdominal wound complicated by a myelodysplastic syndrome (Figure 5A). The wound, which had been open for more than 2 months, was initially debrided and managed with synthetic hybrid-scale fiber matrix (Figure 5B). After 12 days, the wound matrix partially degraded and granulation tissue formed (Figure 5C), allowing flap coverage (Figure 5D). The wound remained closed 4 weeks postoperatively (Figure 5E). The wound became abraded and macerated and fully healed within 3 months.

Case 6

A 50-year-old female with calciphylaxis who was undergoing regular hemodialysis had an ischemic ulcer on the posterior aspect of the lower left leg measuring 12 cm × 6 cm (Figure 6A). The ischemic ulcer had been unsuccessfully managed with topical wound therapy and had been open for more than 3 months. The ulcer was initially debrided (Figure 6B) and managed with synthetic hybrid-scale fiber matrix to test tissue adherence (Figure 6C). After 4 weeks (Figure 6D), new granulation tissue formed at the wound site and rotational flap reconstruction was performed (Figure 6E). After 15 weeks postoperatively, the wound healed with a minor dehiscence of 2 cm × 2 cm (94.4% wound area reduction) (Figure 6F). No signs of infection were seen thereafter. Subsequent closure was achieved within an additional 2 months via outpatient wound care follow-up and conservative treatment (Figure 6G).

Case 7

A 77-year-old female presented with osteomyelitis of the sacral vertebra and severe scoliosis of the sacrolumbar spine that was further complicated by left hip replacement followed by removal of infected hardware. The patient had a stage 4 pressure wound of the sacrum with exposed bone measuring 3 cm × 3 cm for more than 5 months (Figure 7A). The ulcer was initially debrided (Figure 7B) and a bone culture obtained. Three days later, the wound was debrided again and synthetic hybrid-scale fiber matrix was applied (Figure 7C). After 4 days, rotational flap reconstruction was performed (Figure 7D). At 4 weeks postoperatively, the incision was intact (Figure 7E). The wound was nearly healed with minor dehiscence of 0.5 cm × 0.5 cm after 2 months (97.2% wound area reduction) (Figure 7F). No signs or symptoms of infection were seen.

Case 8

A 55-year-old female with functional quadriplegia and chronic right thigh osteomyelitis presented with a stage 4 right ischial pressure wound measuring 4 cm × 4.5 cm that had been open for more than 24 months (Figure 8A). The wound was initially debrided and a synthetic hybrid-scale fiber matrix applied (Figure 8B). After 5 days, the synthetic hybrid-scale fiber matrix started to resorb into the wound bed, which stimulated granulation tissue formation (Figure 8C), and rotational flap reconstruction was performed (Figure 8D). The surgical incision remained intact and infection free until discharge 20 days after flap closure (Figure 8E).

Case 9

A 52-year-old male with quadriplegia and chronic bilateral osteomyelitis of the right and left ischial spine presented with stage 4 pressure wounds of the right and left ischii measuring 3 cm × 3.2 cm and 3.3 cm × 3.2 cm, respectively. The ulcer was open for more than 36 months (Figure 9A [right], B [left]). Both wounds were initially debrided and synthetic hybrid-scale fiber matrix placed (Figure 9C [right], D [left]). After 5 days, rotational flap reconstruction was performed for both wounds (Figure 9E [right], F [left]). The incisions were complicated by chronic candidiasis of the skin, and after 3 weeks revision of the right ischial incision was performed (Figure 9G). Both incisions were completely healed by 8 weeks postoperatively (Figure 9H [right], I [left]).

Case 10

A 69-year-old male had multiple sclerosis and hemiplegia following a cerebral infarction affecting the left side. He presented with a stage 4 pressure wound to the left ischium that had been open for more than 3 months (Figure 10A). The patient underwent initial debridement (Figure 10B). A second debridement was done 3 days later, and synthetic hybrid-scale fiber matrix was placed on the wound bed (Figure 10C). After 4 days, rotational flap reconstruction was performed (Figure 10D). After 2 months, the incision was healed (Figure 10E).

Case 11

In an 80-year-old male, a stage 4 pressure wound to the sacrum developed following an intensive care unit stay for exacerbation of chronic obstructive pulmonary disease, subsequent metabolic encephalopathy, and bacterial pneumonia. The wound had been present for less than 6 months and measured 13 cm × 16 cm. Debridement was performed (Figure 11A), and synthetic hybrid-scale fiber matrix was applied to the wound (Figure 11B). After 2 days, the patient underwent rotational flap reconstruction of the sacrum under general anesthesia. The wound healing process was visible at the 3-week follow-up (Figure 11C), and the wound was completely healed by 6 weeks postoperatively (Figure 11D).

This retrospective study presented a novel treatment method for complex pressure ulcers. After sharp debridement, the synthetic hybrid-scale fiber matrix was applied to the wound bed. This matrix was applied to promote granulation tissue formation and enhance the natural wound healing process. Long-term success of flap reconstruction procedures has been correlated with the quality of granulation tissue within the wound bed.⁶ Application of grafts or other tissue matrices has been shown to improve tissue quality and coverage of exposed structures. In the cases reported here, flap reconstruction was performed between 4 days and 14 days after application of the surgical matrix. A follow-up period of 20 days to 165 days was commenced to evaluate the wound conditions.

Flap reconstruction of chronic pressure ulcer is associated with various complication rates, including wound dehiscence (31.2%¹) and ulcer recurrence (27%¹⁰ and 28.6%¹). In the current study, however, no adverse event was observed after wound matrix application and ensuing flap reconstruction. Overall, synthetic hybrid-scale fiber matrix was used successfully to manage pressure ulcers, with a wound closure rate of 90.9% (10 cases of complete wound closure and 1 case of 97.2% wound area reduction).

The synthetic hybrid-scale fiber matrix provides added benefits compared with the existing biologic solutions. The synthetic nature of this matrix makes it resistant to the enzymatic degradation that causes premature degradation of collagen-based material due to overexpressed protease in the chronic wounds.⁷ Moreover, it has been previously reported that the degradation products formed upon hydrolysis of the synthetic hybrid-scale fiber matrix, including lactic acid and polylactic acid, demonstrate antimicrobial effects that may be beneficial to wound healing.^7,11 The surface area and porosity of the matrix allow for cell infiltration and attachment. When the matrix is applied to the wound site the porosity increases as the matrix gradually biodegrades, which supports cellular infiltration, neovascularization, and reepithelialization. The advantages of synthetic construction and similarity to the structure of native ECM make the synthetic hybrid-scale fiber matrix a novel wound therapy that warrants further detailed investigation.

Future studies may be conducted to comparatively evaluate the healing rate of wounds managed with synthetic hybrid-scale fiber matrix versus other advanced therapies, including dermal regeneration template (Dermal Regeneration Template; Integra LifeSciences Corporation), bilayered bioengineered skin substitute (Apligraf; Organogenesis), regenerative matrix (Hyalomatrix; Medline Industries, Inc.), homologous grafts, or synthetic matrices. In a study by Prystowsky et al,¹² the dermal regeneration template, which is composed of a matrix of cross-linked fibers and an outer silicone layer, was used in the management of leg ulcers. Complete wound healing was achieved in 25 of 31 wounds. In a randomized clinical study,¹³ 33 patients with neuropathic diabetic foot ulcer were treated with the living bilayered skin substitute made of an epidermal layer including keratinocytes and a collagen-based dermal layer including fibroblasts.Twelve weeks postoperatively, 51.5% (17/33) of wounds had healed, compared with a 26.3% (10/38) healing rate for wounds managed using standard dressings. The regenerative matrix composed of fibers made of a benzyl ester of hyaluronic acid (HYAFF; Anika Therapeutics) with a silicone outer layer that acts as a barrier against external agents, encourages cell migration and leads to new dermal tissue reconstruction. In a clinical study,¹⁴ deep partial-thickness burns in 300 patients were managed with regenerative matrix.Of those, 83% (250 wounds) healed with minimal complications.  Data available to date suggest that the synthetic hybrid-scale fiber matrix is more efficient in supporting the wound healing.^7,15 Overall, conducting a study to evaluate healing of chronic wounds managed using the synthetic hybrid-scale fiber matrix compared with other competitive products may reveal more benefits of using this matrix.

A limitation of this study was the absence of a control group including patients who received the standard-of-care treatment. To determine the efficiency of managing pressure ulcers with the synthetic hybrid-scale fiber matrix, treatment outcomes should be compared with outcomes of the standard-of-care treatment in a double-arm clinical study.

Use of synthetic hybrid-scale fiber matrix allows cellular ingrowth and granulation tissue formation, which improves tissue quality and wound site preparation for subsequent surgery. The outcomes of this study show the potential benefits of the synthetic hybrid-scale fiber matrix integration to the wound bed prior to flap closure and successful lasting wound closure following flap reconstruction. The present study demonstrates the feasibility of using the synthetic hybrid-scale fiber matrix in the setting of pressure ulcer reconstruction. Future studies will aim to build on these findings and expand the investigation of augmented flap reconstruction to a larger subset of patients across multiple health care facilities.

Authors: Mary Vallery, RN; and Thomas Shannon, MD

Affiliation: Nexus Wound Care, Shenandoah, TX

Correspondence: Thomas Shannon, MD, Wound Care Medical Director, Nexus Wound Care, 300 Vision Park Blvd, Shenandoah, TX 77380; tomshannon@att.net

Disclosure: The authors disclose no financial or other conflicts of interest.