Human experience with a biodegradable polyurethane scaffold I: Short-term implantation

Transcription

1 Human experience with a biodegradable polyurethane scaffold I: Short-term implantation A/Prof. John E Greenwood AM BSc(Hons), MBChB, MD, FRCS(Eng.), FRCS(Plast.), FRACS Director, Burns Unit, Royal Adelaide Hospital ABA 45 th Annual Meeting, Palm Springs 23 rd 26 th April

2 Disclosure I have the following relevant potential financial relationship NovoSkin Pty. Ltd. & NovoWound Pty. Ltd. My company (Skin Pty. Ltd., of which I am one of two equal owner/directors) owns 20% of both NovoSkin Pty. Ltd. & NovoWound Pty. Ltd. The remaining 80% of NovoSkin Pty. Ltd. & NovoWound Pty. Ltd. is owned by PolyNovo Biomaterials Pty. Ltd. (the manufacturer and IP holder of the NovoSorb biodegradable polyurethane platform). I act to assist in the design of the polymer products (by specifying desirable properties) for the field of deep burn injury and wound management, and to perform the laboratory, animal and clinical research aspects during its development. I have not, and do not currently, receive any salary, or other payment, from this relationship.

3 Trial Objectives To assess what, if any, reaction might be observed by clinical signs, or identified by symptoms, in (and around) a wound which is exposed to the biodegradable polymer for a short length of time (48 hours) To assess the ability of the biodegradable polyurethane foam (NovoSorb ) to act as a Negative Pressure Wound Therapy interface and the effectiveness with which it performs that function, compared to a commercially available and widely-used alternative interface (Granufoam ) FDA releases - concerns regarding bleeding and infection using NPWT (mainly Granufoam ) in 2009 and 2011 (total 12 deaths and 174 injuries since 2007)

4 Trial Design Twenty decubitus ulcers (ischial, sacral or heel) being managed in the community with conventional dressings by RDNS nurses Aged between 18 and 70 years Short term admission for surgical debridement, randomisation and NPWT commencement Dressing changes every 2 or 3 days at home (Mon/Wed/Fri) until healing or 8 weeks (whichever came first) KCI supplied ActiVacs, tubing and TrakPads, sealing films and control foam (Granufoam ), PolyNovo supplied sterile, packaged treatment foam (NovoSorb )

5 Objective 1 NovoSorb safety in short-term exposure No signs of irritation, erythema, rash, blistering, peri-wound oedema were seen with any NovoSorb dressing No symptoms of adverse reaction (itch, discomfort, pain) were reported by any patient with NovoSorb dressings

6 Objective 2 NovoSorb efficacy as a TNPT interface Every wound, in every patient, with both materials demonstrated significant decrease in size over the trial period No significant difference in wound size reduction between Granufoam and NovoSorb groups at Day 15 (p=0.52), Day 35 (p=0.76) and Day 50 (p=0.37)

7 Mean group wound size as a percentage of original wound size Granufoam NovoSorb p= p= p= Day

8 Temporal series: Ischial wound with NovoSorb TNPT interface 54.4cm cm cm cm cm cm cm cm 2

9 Handling NovoSorb denser, more difficult to shape with scissors, but no fine filament shedding. Not suitable for bridging to Trak-Pad. Less is more. Difficult removal of foam in 40 of 50 Granufoam changes in ischial cavity wounds (80%). All NovoSorb changes in these wounds easy. No marginal invasion of granulation tissue into NovoSorb, therefore No granulation tissue trauma during NovoSorb removal and thus no cavity wall granulation bleeding seen in this study

10 Handling (2) Less fragmentation with NovoSorb (14/72 changes, 19.4%), compared to Granufoam (21/69 changes, 30.4%). Retention of foam in 5 patients (4 Granufoam, 1 NovoSorb ). NovoSorb fragments washed out completely with saline. Three of four (75%) Granufoam fragment retentions required sharp debridement for removal. Infection followed in these three patients by the next dressing change.

11 Difficult removal with bleeding Foam retention with infection Patient 3 (Granufoam ) displaying infection at the site of foam retention and demonstrating friable, vascular granulations with slight bleeding

12 NovoSorb Fragmentation

13 Summary No symptomatic or clinical sign evidence of adverse wound, or peri-wound, reaction to the presence of the biodegradable polymer foam (NovoSorb ) interface. No statistically significant difference in efficacy between NovoSorb and the control material, Granufoam in wound area decrease with time. Foam removal (particularly in deep cavity wounds) easier, and thus less traumatic to granulations, with NovoSorb. Retention higher and more frequently requiring sharp debridement with Granufoam in deep cavity wounds. Infection commonly followed retention and its debridement.

14 Human experience with a biodegradable polyurethane scaffold II: Long-term implantation A/Prof. John E Greenwood AM BSc(Hons), MBChB, MD, FRCS(Eng.), FRCS(Plast.), FRACS Director, Burns Unit, Royal Adelaide Hospital ABA 45 th Annual Meeting, Palm Springs 23 rd 26 th April 2013

15 Disclosure I have the following relevant potential financial relationship > NovoSkin Pty. Ltd. & NovoWound Pty. Ltd. > My company (Skin Pty. Ltd., of which I am one of two equal owner/directors) owns 20% of NovoSkin Pty. Ltd. & NovoWound Pty. Ltd. The remaining 80% of NovoSkin Pty. Ltd. & NovoWound Pty. Ltd. is owned by PolyNovo Biomaterials Pty. Ltd. (the manufacturer and IP holder of the NovoSorb biodegradable polyurethane platform). > I act to assist in the design of the polymer products (by specifying desirable properties) for the field of deep burn injury and perform the laboratory, animal and clinical research aspects of its development. > I have not and do not currently receive any salary, or other payment, from this relationship.

16 Trial Objectives To assess the ease of handling, use and fixation during surgical implantation of the optimised BTM (Biodegradable Temporising Matrix) To monitor and evaluate the integration of the BTM over the subsequent three weeks in terms of wound size and health To assess the quality of integration and vascularisation by its ability to receive autograft To record the longer term cosmetic and functional results

17 Trial Design Ten patients with deep free-flap donor sites (anterolateral thigh, fibular or radial forearm) Aged between 18 and 70 years BTM implanted at first operation Monitoring as in- or out-patient over the next 21 days BTM delaminated, dermal surface refreshed by dermabrasion and split-skin autograft applied at Day 21 Ongoing monitoring for graft health and take, wound size, function (mobility, suppleness) and appearance (depression, colour)

18 Day 0 ALT donor wound with BTM (131.9cm 2 ) ABA 45 th Annual Meeting, Palm Springs 23 rd 26 th April 2013

19 Day 22 pre-delamination (130.3cm 2 )

20 Day 22 post-delamination post-dermabrasion (130.3cm 2 )

21 Day 34 post-delamination post-dermabrasion (135.2cm 2 )

22 Day 34 graft application (135.2cm 2 )

23 Day 46 post grafting (118.3cm 2 )

24 Day 61 post-implantation, 27 days post-grafting (130.6cm 2 )

25 Day 61 post-implantation (130.6cm 2 )

26 Day 0 (33.5cm 2 ) Day 0 post-btm implantation Day 5 (31.7cm 2 ) Day 14 (35.6cm 2 ) Day 21 post-delamination Day 21 post-grafting Six weeks post-grafting (23.1cm 2 ) Three months post-grafting

27 Summary Six of ten patients recruited at this stage (3 anterolateral thigh flaps, 3 fibular flaps) Although model far from ideal (patients generally elderly, unwell with malignant disease, undergoing extensive and lengthy surgery, etc.), BTM seems to integrate well and rapidly into these cold wounds Wound size reduction occurs post-delamination and autograft application, but wound size largely maintained during BTM take Result flush with surrounding skin despite depth of wound and thickness of BTM, mobile and robust HREC approval for pilot burn trial (20-50% TBSA) once BTM trial concluded