A Biodegradable Polyurethane Dermal Matrix in Reconstruction of Free Flap Donor Sites

A Pilot Study

Marcus J.D. Wagstaff, BSc(Hons), MBBS, PhD, FRCS(Plast), FRACS; Bradley J. Schmitt, BAppSc, MPhys; Patrick Coghlan, MBBS; James P. Finkemeyer, BBioMedSci, BMBS; Yugesh Caplash, MBBS, MS, MCh, FRACS; John E. Greenwood, AM, BSc(Hons), MBChB, MD, DHlthSc, FRCS(Eng), FRCS(Plast), FRACS


ePlasty. 2015;15 

In This Article


A temporal pictorial record of each patient's course was generated, a selection of which has been included. Table 1 contains a summary of the outcomes of each case, including wound surface areas expressed as a percentage of the original wound at the time of definitive skin grafting and at the nearest time point to death (patients 1 and 2) or 1 year postimplantation. Scar scores at 1 year are also included. Additional pertinent information for each case is presented later.

Patient 1

The BTM appeared to integrate despite the patient's obvious physical frailty and slowness to heal in his other wounds. In theatre on day 22, following delamination, we saw that part of the polymer had failed to adhere and integrate over the intermuscular septum, due to the presence of an encapsulated seroma. This portion of the BTM was excised (24% of the total). The remainder was dermabraded and the skin graft applied. Despite an apparently vascularized bed, including over the muscle where the BTM had been removed, the graft failed except for a crescentic fragment along the lateral margin (over the integrated BTM), covering 14.5% of the total wound area.

The failed graft was removed on the ward and the wound redressed. The integrated BTM was refreshed by dermabrasion and the residual wound regrafted on day 34. Residual BTM was visibly retained in the wound following the second dermabrasion. He was discharged with 100% graft take. Shortly after an assessment at day 71, he died secondary to pneumonia. No scar assessment was made.

Patient 2

The BTM was inspected on day 3 and the patient appeared healthy. On day 6, the BTM showed gray discoloration along its medial border and on day 10, infection was clinically obvious. Incontinence secondary to a urinary tract infection had resulted in infected urine leaking onto his wound dressing. Enterobacter was cultured. The central part of the BTM (37% of the total) was excised. The wound underwent daily cleaning and fresh antimicrobial dressings (Acticoat). The remaining BTM (63%) continued to integrate into the wound. Delamination of the residual seal, surface dermabrasion, and split-skin grafting were performed at day 20. The graft was meshed to reduce potential graft problems related to the previous infection. There was 100% skin graft take across the whole wound. His last assessment was at day 213 prior to his death due to metastatic disease. No scar assessment was made.

Patient 3

The BTM was delaminated at day 20 and had failed to adhere and integrate over the peroneus longus tendon. This portion was removed (10% of the total wound area). The skin graft took anteriorly over the integrated BTM but failed posteriorly over the exposed tendon. Further grafting was unnecessary.

Patient 4

The clinical course proceeded uneventfully (Fig 1).

Figure 1.

Patient 4 temporal series (FOC). Implantation (a,b), integration (c,d), grafting (e), graft take (f), and maturation (g,h) to 1 year.

Patient 5

The BTM integrated fully; however, delamination, dermabrasion, and split-skin grafting were delayed until day 29 due to issues relating to the tumour site reconstruction.

Patient 6 ( Fig 2)

Figure 2.

Patient 6 temporal series (UF). Demonstrates complex ulnar forearm free flap donor site (a), BTM integration (b-d), appearance post-dermabrasion (e), grafting (f), and graft maturation (g-j) to 1 year.

A serous collection under the central area was noted (day 17) (overlying the tendon sheaths) with delayed BTM integration compared to peripheral areas. The seal was partially removed on day 19 allowing fluid escape. The BTM dermal component integrated over the next week. At day 36, the residual seal was delaminated, the BTM dermabraded, and split-skin graft was applied, which took completely.

Patient 7

The BTM integrated without issue. Readmitted for delamination, dermabrasion, and successful split-skin grafting at day 34 (the over-tendon integration time set by experience with patient 6).

Patient 8

During flap harvest, part of the rectus femoris muscle was devitalized (Fig 3). The BTM overlying this compromised muscle failed to adhere and was removed on day 10 (representing 16% of the total BTM on Visitrak measurement). On day 18, the muscle was obviously necrotic and required surgical debridement. A coliform/anaerobe abscess was discovered under the necrotic muscle. Its proximity had not affected the integration of the remaining adjacent BTM. A topical negative pressure dressing was applied to the whole wound. At day 25, the dressing was removed and the remaining 84% of the BTM was delaminated, dermabraded, and grafted, with 100% graft take across the whole wound.

Figure 3.

Anterolateral thigh flap donor site at creation (a), note the muscular color difference in proximomedial quadrant. Biodegradable temporizing matrix (BTM) integration (b) marred in the same quadrant. Obvious muscle nonviability (c,d) followed by excision of the nonviable rectus femoris and release of a coliform/anaerobe abscess deep to the dead muscle leaving defect (e). Note that the remainder of the BTM is intact despite the abscess proximity although delaminated in the proximolateral quadrant. After the negative pressure wound therapy (NPWT) treatment, total BTM delamination and dermabrasion (f). Graft 10 days later (h) and with maturation to 12 months (i,j).

Patient 9

On day 14, the BTM seal lifted over a turbid fluid collection (Fig 4). This area of raised seal was excised and a fluid sample sent for microbiological culture. Staphylococcus aureus was reported. Intravenous antibiotics were commenced and antimicrobial dressings were changed daily. The BTM persisted and subsequently fully integrated. The patient demonstrated no outward sign or symptom related to this infection. He was readmitted at day 35 for delamination of the residual seal, dermabrasion, and split-skin grafting.

Figure 4.

Patient 9 temporal series (RF) illustrating infection and resolution. Complex wound bed at flap harvest (a), progression of integration (b), and infection within the matrix at 14 days (c). Treatment by partial delamination and topical wound management eradicates the infection while the matrix persists (d). By day 35, BTM is integrated and grafted (e,f). Graft take (g), remodeling, and maturation (h,i).

Patient 10

On day 19, a turbid collection was noted under the BTM seal, lifting the seal locally. He was asymptomatic. The seal was windowed to allow fluid escape. A daily antimicrobial dressing regime was commenced with oral antibiotic administration. A wound fluid sample cultured mixed anaerobes. The BTM integration appeared slow over the tendons, and skin grafting was scheduled for 6 weeks postimplantation. However, domestic issues postponed delamination of the residual seal, dermabrasion, and skin grafting to day 49 (7 weeks). Although the skin graft adhered at 4 days postapplication and had visibly taken and was maturing at day 61, the central graft over the flexor carpi radialis tendon broke down following gardening trauma first noted at day 106. The underlying tendon was not exposed and remained covered with vascularized tissue. This was treated with dressings until healing was complete at day 239.

Local Adverse Reactions

Patient 2 exhibited signs of surrounding skin inflammation secondary to severe culture positive wound infection caused by contamination with infected urine. In patients 9 (Fig 4) and 10, where serous fluid collecting under the seal cultured positive for bacteria, the surrounding skin did not become inflamed, nor was inflammation seen around the wound containing the deep abscess in patient 8 (Fig 3). Patient 7 developed a reaction to the poliglecaprone sutures used to secure the graft first noticed on day 26 postgraft application, which settled after suture removal. No patients complained of pruritus or pain directly attributable to the BTM.

Wound Area

The ALT flap group (patients 1, 2, and 8) exhibited an overall slight increase in wound area during BTM integration, which then contracted to below the original size to around day 90 (representing a point of maximal scar activity). After this point the wound increased in size in both remaining patients over the remaining months of study.

The wound areas at grafting in 2 of the FOC flap group (patients 3 and 4) exceeded the original size. Patient 5's wound size (who was grafted at a later time point) initially increased to day 20 and then decreased over the next 9 days. Over the remaining months, all 3 wounds contracted to a mean of 69.15% of original size.

In the RF/UF flap group (patients 6, 7, 9, and 10), a decrease in wound area at skin grafting was noted in all patients (mean = 73.57%), which may reflect the overall trend of contraction relating to the increased time to graft afforded to these patients to allow for integration overexposed tendons (mean graft day = 38.5). These wounds contracted more than the other groups (power too small for statistical comparison), with a mean area of 36.64% of original size at 1 year.

Scar Outcomes

The POSAS Observer scale and MAPS scar assessments were completed on 8 participants at approximately 1 year (mean = 370.88 days) follow-up appointment. Only 7 participants were able to complete the POSAS Scale, as 1 patient (patient 5) was unable to communicate secondary to oral tumour recurrence. Table 2 contains a summary of scores from the 2 scar assessments. All participants reported no itch or pain (ie, score 1/10) from their scar in the previous 4 weeks on the POSAS Patient Scale.