Human experience with a biodegradable polyurethane scaffold I: - - PowerPoint PPT Presentation

ABA 45th Annual Meeting, Palm Springs 23rd – 26th April 2013

A/Prof. John E Greenwood AM

BSc(Hons), MBChB, MD, FRCS(Eng.), FRCS(Plast.), FRACS Director, Burns Unit, Royal Adelaide Hospital

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

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
• wner/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.

Disclosure

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)

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™)

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

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)

10 20 30 40 50 60 70 80 90 100 5 10 15 20 25 30 35 40 45 50

Granufoam NovoSorb

Day Mean group wound size as a percentage of original wound size

p=0.37 p=0.52 p=0.76

54.4cm2 30.8cm2 27.5cm2 21.1cm2 20.2cm2 17.2cm2 11.2cm2 11.1cm2

Temporal series: Ischial wound with NovoSorb™ TNPT interface

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

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.

Foam retention with infection Difficult removal with bleeding

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

NovoSorb™ Fragmentation

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.

ABA 45th Annual Meeting, Palm Springs 23rd – 26th April 2013

A/Prof. John E Greenwood AM

BSc(Hons), MBChB, MD, FRCS(Eng.), FRCS(Plast.), FRACS Director, Burns Unit, Royal Adelaide Hospital

Human experience with a biodegradable polyurethane scaffold II: Long-term implantation

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

• wner/directors) owns 20% of NovoSkin Pty. Ltd. & NovoWound Pty.
• Ltd. The remaining 80% of NovoSkin Pty. Ltd. & NovoWound Pty. Ltd. is
• wned 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.

Disclosure

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

• f 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

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)

ABA 45th Annual Meeting, Palm Springs 23rd – 26th April 2013

Day 0 – ALT donor wound with BTM (131.9cm2)

Day 22 – pre-delamination (130.3cm2)

Day 22 – post-delamination post-dermabrasion (130.3cm2)

Day 34 – post-delamination post-dermabrasion (135.2cm2)

Day 34 – graft application (135.2cm2)

Day 46 – post grafting (118.3cm2)

Day 61 – post-implantation, 27 days post-grafting (130.6cm2)

Day 61 post-implantation (130.6cm2)

Day 0 (33.5cm2) Day 0 – post-BTM implantation Day 5 (31.7cm2) Day 14 (35.6cm2) Day 21 – post-delamination Day 21 – post-grafting Six weeks post-grafting (23.1cm2) Three months post-grafting

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