The Prevena Restor Bella.FormTM in the management of lower limb traumatic wounds

Objectives: The Prevena Restor Bella.Form TM is a novel closed incisional negative pressure wound therapy with a 14 day lifespan and a large contact area. This study aims to demonstrate the utility of the Prevena Restor Bella. Form TM in high risk lower limb traumatic wounds. Methods: 4 consecutive patients with complex traumatic lower limb wounds were included. The Prevena Restor Bella.Form TM was applied as a primary therapy or an adjunct to soft tissue reconstruction. Wounds were monitored fortnightly, limb circumference measured and patient satisfaction assessed by a questionnaire. All 4 patients healed within 6 weeks of Prevena application. Results: No cases developed wound complications. Limb oedema, assessed by circumference, decreased in all patients within 2 weeks. All patients were satisfied with the Prevena Restor Bella.Form TM with regards to comfort and mobility. Conclusions: Prevena Restor Bella.Form TM demonstrated clinical effectiveness in all patients, and was universally well tolerated.


Introduction
Between 2020 and 2021, traumatic injuries were responsible for 8.4% of the disease burden and 7.9% of healthcare expenditure ($8.9 billion) in Australia 1 .Lower limb injuries account for 25% of these injuries, representing a significant healthcare burden.Lower limb trauma presents many issues for wound healing, including the tendency to develop limb oedema as well as a vulnerability to vascular disease.Even directly closable wounds from a significant mechanism of injury, or in the setting of diabetes mellitus, is at risk of wound infection, oedema and dehiscence 2,3 .Any mechanism that can aid wound healing thus has great application for lower limb trauma.
Negative pressure wound therapy (NPWT) is one such mechanism, and has demonstrated many benefits, including reducing oedema, creating a sterile barrier, offering continuous negative pressure and reducing tension across a wound line 4 .Utilisation of closed incisional NPWT (ciNPWT) is in its infancy, however via the induction of angiogenesis, maintaining a sterile wound environment and wound oedema reduction, ciNPWT has clinical utility in wounds at high risk of breakdown.Previous studies on ciNPWT have predominantly focused on elective breast, elective abdominal and elective lower limb orthopaedic wounds, thus ciNPWT is now becoming part of routine wound management at some major centres [5][6][7] .A recent 2019 meeting in the United States of America found an expert panel who recommended the use of ciNPWT in high risk patients and high risk wounds 8 .This meeting neglected some of the highest risk wounds in surgery, those secondary to lower limb trauma.Despite meta-analyses describing the benefits of ciNPWT on wound infections and dehiscence in orthopaedic trauma 9 , this treatment modality is potentially under-utilised.
The Prevena Restor Bella.Form TM dressing is a larger ciNPWT with a 0.019% ionic silver impregnated dressing foam, made to surface large contoured wounds, such as in breast surgery and lower limb vascular amputations, and has demonstrated benefits in wound healing in those contexts 10 .The application of the Prevena Restor Bella.Form TM to lower limb wounds has great clinical potential, however is insufficiently studied.
As such, this study hopes to identify the impact of the Prevena Restor Bella.Form TM in a subset of high risk lower limb wounds.We aim to explore the dressing's effect on healing time, the rate of wound complication development, and the quantifiable impact on lower limb oedema in traumatic lower limb wounds.

Methods
This study was a case series of 4 consecutive patients referred to a single plastic surgeon between June and August of 2022 for advice regarding traumatic lower limb wounds.Inclusion criteria included being 18 years old or more, having a lower limb wound sustained from trauma, having capacity to consent to inclusion in the study and having a wound where NPWT was part of the appropriate clinical management.Oedema and lower limb swelling was a key component to the wound complexity in all patients and patients were either not fit for vascularised flap coverage or less invasive surgical reconstructions were preferred.The Prevena Restor Bella.Form TM was then applied, either as a sole therapy or as an adjunct to surgical management at the time of reconstruction with split thickness skin grafts (STSG).All patients were fitted with a loose compressive circumferential wool and crepe bandage from toes to knees.Mobility restrictions were decided on a case-bycase basis.All patients were advised to keep their leg elevated when at rest.Patients had their limb circumference measured 3cm proximal to the lateral malleolus, 3cm inferior to the fibula head and at a point halfway between these 2 landmarks at the time of Prevena Restor Bella.Form TM application.The Prevena Restor Bella.Form TM has a battery life of 2 weeks, so patients were followed up at 2-week intervals where they had their wounds inspected for signs of infection, dehiscence, discharge and skin integrity.Limb circumference was re-measured to assess degree of oedema at 2-and 4-weeks post application of the Prevena Restor Bella.Form TM .The Prevena Restor Bella.Form TM was ceased once the wound was clinically determined to be healed and stable.
Patients had their satisfaction with the device assessed once treatment was completed, consisting of 5 questions (Table 1).These questions were designed to assess impact of the device on daily activities, overall hospital experience, device comfort and mobilisation.This case series represents a predominantly qualitative study with purely descriptive statistics.No statistical analysis was conducted.The STROBE STATEMENT was used to ensure proper reporting of methods, results and discussion.

Case 1
This 84-year-old female sustained an open tri-malleolar fracture following a fall which required open reduction and internal fixation (ORIF).She had a background of ischaemic heart disease, type 2 diabetes and previous strokes.She was referred with lateral leg incisional flap tip necrosis with threatened exposed underlying metalware at her initial wound review following ORIF (Figure 1).Given she was a poor free flap candidate due to her comorbidities, the decision was made to minimally debride and manage conservatively with the ciNPWT.Following her 2-week wound review which showed incremental improvement, the patient was transferred to a rehabilitation facility.After 6 weeks of Prevena Restor Bella.Form TM , secondary intention healing had adequately progressed and she was deemed fully healed and weight baring commenced, in keeping with orthopaedic recommendations and her stable wound.A 64-year-old male was referred with an open distal tibial periprosthetic fracture following a fall.He had a background of a tibial ORIF 10 years prior and obesity.He underwent debridement, removal of metalware, tibial ORIF and an ankle fusion.He had soft tissue loss laterally that was reconstructed with an anterolateral thigh flap.At day 21 there was delayed healing at the distal flap inset, as well as leg and flap oedema and a 5x5mm grade 2 achilles pressure ulcer.Given the wounds were at risk of deterioration, to prevent debridement and need for further reconstruction of exposed metalware, the decision was made to utilise the Prevena Restor Bella.Form TM to manage oedema and encourage wound healing.Following application of the Prevena Restor Bella.Form TM for 4 weeks, all wounds had fully healed with a reduction in oedema (Figure 2).

Case 3
A 39-year-old male with a crush from an excavator sustained midfoot and ankle fractures.He had a history of dorsal foot burns and a previous skin graft 5 years prior.Dorsal foot swelling progressed resulting in an 8x8cm area of dorsal foot skin necrosis over the previous skin graft requiring debridement at the time of ORIF (Figure 3).An artificial dermal matrix (ADM) was applied for coverage over the pre-existing scarred wound bed, and a Prevena Restor Bella.Form TM over the ADM.Following 4 weeks of NPWT, oedema had reduced and the ADM fully integrated.A STSG was applied with an overlying Prevena Restor Bella.Form TM .The patient was kept resting in bed, only allowed to ambulate to the toilet and kept in a CAM boot.After 2 weeks the graft had fully taken, and at 4 weeks the wound stable enough to cease NPWT (Figure 4).

Case 4
A 29-year-old female with a background of obesity developed a spontaneous lower limb compartment syndrome requiring fasciotomies and serial debridement of necrotic anterior and lateral compartment musculature.The resultant lower limb was grossly oedematous.The lateral fasciotomy wound was not directly closable and given the residual significant contour deformity to her medial leg, an ADM was applied with an overlying Prevena Restor Bella.Form TM .After 4 weeks the ADM was reconstructed with a STSG and the Prevena Restor Bella.Form TM applied again.She progressed well at her 2 week wound review and was fully healed at 4 weeks post-operatively (Figure 5).
Survey feedback was 100%.Patients universally were satisfied with the Prevena Restor Bella.Form TM and scored the dressing either 'Very Good' or 'Excellent' with respects to comfort and range of motion (Table 1).All 4 limbs demonstrated a reduction in their limb circumference following Prevena Restor Bella.Form TM application (Table 2).

Discussion
This study aimed to demonstrate the effectiveness of the Prevena Restor Bella.Form TM in treating traumatic lower limb wounds.In our series of 4 patients, the universal experience was of a healed wound within 6 weeks of device application or 4 weeks from the time of reconstruction.All patients had barriers to healing, particularly related to mechanism of injury and underlying comorbidities, yet none progressed in wound breakdown following application of the Prevena Restor Bella.Form TM .
Via its size, the Prevena Restor Bella.Form TM is able to create a near circumferential contact area over lower limbs.This enables it to broaden its effect to the entire zone of injury, and sometimes beyond this where dependent oedema accumulates.Limb oedema compromises wound healing, but also worsens post-operative pain and joint stiffness, incredibly important for limb surgery and facilitating earlier access to rehabilitation 11 .
Limb circumference reduced in all 4 subjects, with the most profound effect being within the initial 2 weeks of application (Table 2).Although not quantified in the literature, ciNPWT is speculated to decrease oedema by limiting subcutaneous potential space adjacent the zone of injury, and improving venous and lymphatic drainage 11,12 .Limb circumference is a readily accessible and reliable method for measuring limb oedema 13 , however it is crude and does not account for changes in muscle mass or soft tissue loss, as is the case in 3 out of 4 patients in our series.Future studies may investigate the impact of NPWT on oedema via modern bioimpedance measures 14 .Comparative studies assessing standard dressings, ciNPWT and the Prevena Restor Bella.Form TM may illuminate the quantifiable impact on limb oedema.
Another key finding was the universally positive experience patients had with the Prevena Restor Bella.Form TM , according to the feedback survey (Table 1).All patients were satisfied with the device with respects to daily life, their treatment and report either 'very good' or 'excellent' scores to the questions targeting comfort of the dressing.As previously stated, the dressing is near circumferential, thus is thought to profoundly reduce oedema.This reduction in oedema may result in less stiffness and pain, potentially contributing to the experienced comfort of the Prevena Restor Bella.Form TM .
Patients in cases 3 and 4 had previously been treated with the standard vacuum assisted closure (VAC) dressing prior to involvement in this study.Both patients experienced subjectively better comfort with the Prevena Restor Bella.Form TM , prompting one to report that the Prevena Restor Bella.Form TM "compared to the standard VAC [was] 100% better".Although short and user friendly, our questionnaire is not validated or standardised.Validated questionnaires may be employed in future studies to quantify the patient experience of the Prevena Restor Bella.Form TM .This would aid in comparison of patient experience with the Prevena  Restor Bella.Form TM with other dressings, and should be considered in potential future prospective study design.
Another advantage of the Prevena Restor Bella.Form TM is the 2 week life span of the dressing and its battery.Compared to the standard VAC, the Prevena battery is compact, lighter and not reliant on daily charging, being convenient to the patient and decreasing the regularity of clinic visits for both patients and hospital staff.This also increases the lifespan of the primary dressing applied at surgery to 2 weeks.Although various cost effectiveness studies have not demonstrated a clear cost benefit for the use of ciNPWT 15 , it is worth noting that these studies compared NPWT techniques versus standard simple dressings regimens.An internal comparison was made between the 14day Prevena Restor Bella.Form TM dressings and the cost of a standard VAC with a foam change at 1 week, demonstrating a cheaper price of AUD$795 for the Prevena Restor Bella.Form TM versus AUD$808 for the VAC.This is particularly beneficial for traumatic lower limb wounds with soft tissue loss requiring skin grafts where VAC dressings are used to stabilise STSGs, highlighting a potential subgroup of limb wounds where the Prevena Restor Bella.Form TM would be both clinically and economically superior.This case series demonstrates the successful use of the Prevena Restor Bella.Form TM on traumatic lower limb wounds.Limited by the small sample size and the lack of a control group, this study highlights the need for future larger randomised controlled trials exploring the use of Prevena Restor Bella.Form TM , in particular comparing the Prevena Restor Bella.Form TM with commonly used NPWT dressings and attempting to quantify oedema reduction by assessing tissue bioimpedance.

Figure 1 :
Figure 1: Case 1. Left -lateral leg wound with compromised necrotic flap tip pre-application of Prevena; Central -leg with Prevena in situ; Right -Fully healed wound 6 weeks following initial Prevena application.

Figure 3 :
Figure 3: Wound progression in case 3. From left to right: Dorsal foot skin necrosis following crush injury; Skin defect post initial debridement; Skin defect following mid-foot open reduction internal fixation and further debridement; Post application of acellular dermal matrix (ADM); Prevena applied over the ADM.

Table 1 :
Patient questionnaire responses following treatment course of Prevena Restor Bella.Form TM

Table 2 :
Leg circumferences in cm prior to Prevena Restor Bella.Form TM application and at 2-week intervals