More than 300 delegates and 36 speakers, representing Europe, America, the Middle East, Canada, Africa, Asia and Australia, convened in Berlin, Germany, in March 2015 for Smith & Nephew’s 6th International Negative Pressure Wound Therapy (NPWT) Expert Meeting. This meeting report focuses on the orthopaedic surgery workstream from this meeting.
This workstream reviewed the evidence for using traditional NPWT in trauma and the evidence for moving to using single-use NPWT on closed surgical incisions. Speakers highlighted the under-reported incidence of orthopaedic infections in hospitals (since most occur after hospital discharge), and discussed the patient-reported outcomes measures (PROMs).
NPWT is considered to be an essential tool for preventing post-orthopaedic surgery complications. NPWT works well in ‘disaster’ wounds and likely many other wounds. It has become a vital tool in managing both complex and high-risk incisional wounds, and is also being used in war zone field hospitals for major trauma surgery. NPWT appears to strengthen wounds and prevent dehiscence. Incisional NPWT (iNPWT) has positive effects on the development of both seroma and wound secretion following spinal surgery.
Increasing evidence supports the use of iNPWT in treating high-risk incisional wounds, as well as for routine use in orthopaedic surgery to minimise wound complications, improve wound healing and reduce length of stay. However, more research needs to be done to clarify the mechanism of action of iNPWT.
Following hip- or knee-replacement surgery, NPWT reduces the length of hospital stay. iNPWT could become the optimal post-operative therapy for use in hip and knee revision surgery. Further trials are necessary to confirm the trends observed in preliminary studies. In situations where wound complications occur frequently, the cost of NPWT is justified.
Trauma surgery: The management of complications following orthopaedic trauma surgery
Chair: Professor James Stannard
Orthopaedic surgeons have to manage complications that are the result of traumatic injury or treatment; this can be influenced by conditions such as diabetes, smoking or obesity. In the context of orthopaedic surgery, complications are typically:
• Wound- or bone-healing disorders
• Surgical-site infection
• Dislocation of hip prosthesis
• Plate fracture.
The effects of these (extended hospital stay, revision operations, distressed patients and increasing costs) are the same everywhere.
Everyone has bacteria on the skin, in the deep tissue and the joints, and most of these bacteria are building a biofilm, he said. Biofilm disease kills more people than cancer1 and is in 80% of implant infections, which means prophylaxis must be considered before surgery.
The relative risk reduction of deep infections following surgery for lower extremity fractures is estimated at 60% for a single-shot antibiotic prophylaxis prior to skin incision and 70% for multiple doses. Long-acting cephalosporins are preferable agents.
NPWT and PICO◊ can improve tissue management, but the surgeon must be aware of contraindications including necrosis, osteomyelitis, anastomosis and the use of anticoagulants with warfarin. NPWT is an essential tool in preventing orthopaedic post-surgical complications.
NPWT is an essential tool in preventing orthopaedic post-surgical complications
Dr Hans Goost
Trauma surgery: Incisional complications in trauma surgery
Professor James Stannard had reviewed the current evidence for the benefits of NPWT use following its introduction in the USA after FDA approval in 1995, initially for very severe injuries. Specifically how it works is unknown, but there are various theories, which include: promoting perfusion, which supports healing; removing excess interstitial fluid or oedema; reducing mechanical stress to the tissues, promoting wound healing/granulation tissue; and stabilising closed incision.
Soon after its introduction, researchers started to examine NPWT and found convincing evidence for its efficacy in traumatic injury management.2 It works well in treating disasters, but prevention would be better: prophylaxis is used routinely in medicine, and is preferable to – and less expensive than – treating a complication.
Investigators began to evaluate the use of NPWT on closed incisions, including one study in 2006 by Professor Stannard. The results were promising but needed more rigorous testing. Professor Stannard set up two randomised controlled trials (RCTs) to examine incisional NPWT’s (iNPWT) efficacy in high-risk fractures3 and the drainage of haematomas.4 The fracture results showed an approximate halving of infection and dehiscence rates in patients treated with iNPWT compared with those treated with standard dressings.
An RCT by Dr Grauhan5 studying the prevention of post-sternotomy wound infections in obese patients by the use of NPWT was ‘a really big deal’, said Professor Stannard. Up to one-third of high-risk patients (average age 68, mean body mass index [BMI] 37, 54% with diabetes) die each year following sternal wound infections. The trial found that with 6–7 days’ prophylactic use of NPWT, the incidence of SSI was reduced from 16% to 4%.
Gaps in evidence include the need for more published data about the PICO◊ system, the role of NPWT with haematomas and seromas, and the mechanism of action of iNPWT. This could be used for elective as well as trauma patients, for high-risk incisions, obese patients and those with poor skin. Single-use disposable systems have changed the opportunities remarkably and routine prophylaxis is becoming more feasible as the cost drops.
With 6–7 days’ prophylactic use of NPWT, the incidence of post-sternotomy wound infections in obese patients was reduced from 16% to 4%.
Professor James Stannard
Trauma surgery: Wound complications in lower-limb trauma
Dr Mazen Ali described his study into the use of PICO◊ in dealing with wound complications in lower-limb trauma. His hospital has a high percentage of traffic accidents so has a long tradition in treating severe and complex traumatic musculoskeletal wounds. The injuries often result in severe and extensive tissue loss and tissue devascularisation, which results in high rates of complication and increased morbidity.
Between June 2012 and June 2014, 37 patients with high-energy injuries were treated with a single-use NPWT PICO◊ dressing, applied immediately after surgery and left in place for five days.6 Wounds and surrounding skin were inspected immediately after removal of the PICO◊ and 30 days post-surgery.
The mean length of treatment was 16 days (8–21) and no complication was registered during or after NPWT PICO◊. It is easily applied, well tolerated and appears to positively improve wound healing outcome. Adequate debridement of wounds is vital before starting NPWT to maximise clinical outcomes.
It has become a vital tool in managing complex wounds and high-risk incisional wounds. It reduces time to wound closure, minimises wound complications, reduces length of hospital stay and improves patient quality of life.
NPWT has become a vital tool in managing complex wounds and high-risk incisional wounds.
Dr Mazen Ali
Trauma surgery: Role of NPWT in major trauma surgery
Professor Steven Jeffery spoke about his clinical experience in treating combat injuries. It is only in the last ten years that triple amputees have survived long enough to reach a surgeon. Now helicopters equipped with resuscitation equipment, blood and medical personnel to administer aid deliver them to a field hospital before they are repatriated.7
With old-fashioned bandages, infections were rife, he said.8 Now they use topical negative pressure, custom-made by Smith & Nephew, in all their field hospitals and ships.9 Conventional dressings often fall off heavily exuding wounds, but this stays in place as it is held in position by the suction.10 This device was designed to handle large-scale traumatic wounds and is the standard of care in field-based hospitals and ships. The dressing system is particularly suited to injuries of the limbs.11
Arthroplasty and spine: Clinical and economic challenges of incisional complications in total joint arthroplasty
Chair: Mr Sudheer Karlakki and Professor James Stannard
Records show there were over 1.3 million hip- and knee-replacement operations in the UK in the 10 years from 2003 to 2013. Each year this figure increases, with higher numbers of patients who are obese, older and have higher numbers of comorbidities. Surgeons therefore have to use chemical thromboprophylaxis, which has huge implications for wound healing and complications.
Mr Sudheer Karlakki’s hospital in Oswestry has done 3000 hip- and knee replacements in 2015 with 350 revisions; it is important to minimise and avoid complications where possible. The hospital, however, is under constant pressure to make cost savings. Length of stay (LOS) is a key performance indicator and Mr Karlakki’s own hospital faces demands to boost its current target of 50% discharge in less than three days, to 80% in the background of difficult staffing conditions brought about by staff shortages and inadequate training.
All these factors lead to an increased risk of surgical-site infections (SSIs), which can significantly affect patient quality of life, morbidity and extended hospital stay. Early but safe discharge is the key, said Mr Karlakki. Hastened discharge can lead to long-term post-discharge complications, which carry huge costs, for the patient and for hospital finances.
Department of Health (DoH) figures for the rates of SSIs in NHS hospitals in England, from 2011–12 showed that hip replacement (0.7% of 170 158 procedures) and knee replacement (0.6% of 182 566 procedures) had the lowest risk of infection.12 However, the DoH also concluded that a significant rise in the number of readmissions following knee replacements was probably because patients were being discharged too early and SSIs were being detected in the community, post-discharge.12
The National Joint Registry (NJR) 2014 annual report on PROMs, pre-operative and six months’ post-operative for total hip replacement (THR), supports this latter observation and points to a much higher rate of orthopaedic infection in the hospital environment.13 However, patients, district nurses and GPs tend to over-react to complications, while surgeons hugely underestimate them because they do not see follow-up; the truth might therefore lie somewhere between the two.
One frequently quoted paper14 found that each day of prolonged wound drainage was associated with an increased risk of infection: 42% after THR and 29% after total knee replacement (TKR).14 The NJR reported 0.8 THR revisions for infection per 1000-patient-years.15
Another paper studying major surgery over a two-year period16 reported an extra median LOS of 10 days attributable to SSI following major surgery (a total of 4694 lost bed days); an increase in readmission for patients who had SSI as an inpatient and an aggregate extra cost to the NHS of £2 491 424.16
Mr Karlakki went on to outline some of the literature relating to the prophylactic use of iNPWT in managing surgical incisions and his own review of the evidence.3,4,17 He concluded by saying there is increasing evidence for its efficacy in treatment of high-risk incisional wounds and evidence is accumulating for its routine use in orthopaedic surgery as a way to minimise wound complications, improve wound healing predictability and reduce LOS. He also referred his audience to a patient grading system to help them decide on whether and when to use NPWT on closed incisions.18
Professor Stannard sees the role of NPWT in trauma surgery as helping the wound to heal: reducing the incidence of infection and dehiscence in severely traumatised soft tissue, stabilising closed incisions and making them stronger.
He investigated the effect of applying iNPWT to the closed surgical incisions of 249 patients with 263 high-risk lower extremity fractures requiring open reduction internal fixation (ORIF), with the aim of preventing wound dehiscence and infection.3 The study was a prospective multicentre RCT, where patients were randomised to receive iNPWT in the study group and standard postoperative dressings in the control group. Results showed that the use of iNPWT with these patients reduced the incidence of infection and dehiscence by about half (19% control versus 10% iNPWT, infection) and (17% control versus 9% iNPWT, dehiscence).3
Professor Stannard, who referred to other studies showing a similar decrease with the use of iNPWT,19–21 said he believed that, with infection dehiscence, NPWT clearly seems to strengthen the wound and prevent dehiscence.
Data suggest there is a significant improvement in wound healing and prophylaxis against infection for patients treated with NPWT over the surgical incision. Professor Stannard wondered if it would be possible to prevent chronic draining postoperative wounds or to treat them. Could a haematoma be sucked out? If not, could the wound over the haematoma be sealed using NPWT?
He set up a prospective randomised study to find out.22 The study was IRB approved and monitored, and 93 patients with 96 wounds were enrolled between 2001 and 2006. Patients were only enrolled if they were draining heavily at five days post-surgery. They were taken to the operating room immediately if they developed an infection and were taken to OR for cultures and incision and drainage if drainage persisted for a total of 10 days.
There was no significant difference between the control and study group in continued drainage after 10 days: once established at five days the haematomas were unresolved. Officially there is no benefit to using NPWT to treat draining haematomas. However, when patients returned, six patients in the standard dressing group but only one in the NPWT group had developed infections, so it may have prevented the draining haematoma from becoming infected. It might have different results if applied immediately after surgery in high-risk patients.
Data from other studies suggest that NPWT may be useful to prevent seromas and haematomas,4,23 but the evidence, to date, is inconclusive and that level 1 evidence is needed.
NPWT clearly works in ‘disaster’ wounds and very probably with many others. Good studies are needed that can prove everything; until then, the cost is justified in any situation where wound complications frequently occur.
There is increasing evidence for its efficacy in treatment of high-risk incisional wounds and evidence is accumulating for its routine use in orthopaedic surgery as a way to minimise wound complications, improve wound healing predictability and reduce LOS.
Mr Sudheer Karlakki
Use of iNPWT in high-risk patients with lower extremity fractures requiring open
reduction internal fixation reduced incidence of both infection and dehiscence by about half.
Professor James Stannard
Arthroplasty and spine: Perioperative medical management for total joint arthroplasty: the fast-track approach
Dr Amerigo Balatri described the genesis and effects of a fast-track approach to perioperative medical management of total joint arthroplasty (TJA).
Surgical materials and techniques were advancing, but the same postoperative care was in use until Professor Henrik Kehlet24 introduced the idea of enhanced recovery after surgery (ERAS) and fast-track programmes in the 1990s, first into colorectal then into orthopaedic surgery.24
ERAS and the fast-track programme were developed by considering, via evidence-based medicine, all the details connected to the perioperative stage, then making the process as efficient as possible, while maintaining safety.
The goal of ERAS is to optimise the patient’s condition prior to surgery and minimise recovery time afterwards: to send a patient home safely and more quickly, with consequent LOS cost savings and increased patient satisfaction. Some evidence also points to a decreased morbidity in perioperative time.
Improvements in the fast-track approach depend on surgeons’ ability to manage the physical aspects of haemostasis, pain and wound infections, but also to prepare patients mentally – aligning their expectations with the surgeon’s and making them feel involved in decision-making. Studies suggest that giving patients more control over their treatment and rehabilitation reduces their anxiety, which is a strong predictive factor for postoperative pain.25
Patient optimisation is not easy because of the short time between the pre-hospitalisation visit and because of the lack of patient compliance, but the aim is to find what you can change from the risk areas that include: poor nutrition, anaemia, diabetes and smoking.
Every day of wound drainage increases risk of infection,14 he said. The solution lies in surgery (irrigation and debridement) or NPWT. The results are the same,26 but now a portable NPWT is available with PICO◊, that is first choice: it doesn’t interrupt physical therapy, allows for discharge at day three.
The use of tranexamic acid (TXA) is a big advance in managing haemostasis, said Dr Balatri. At first there were fears it might give thrombosis and some hypercoagulation, but studies have revealed that there is no increased risk of deep-vein thrombosis (DVT) or pulmonary embolism, and there is a good decrease in blood loss.27 A further advantage is that it facilitates early mobilisation since it allows the elimination of the intra-articular suction drain, which is an obstacle. As a consequence, with early mobilisation, less anticoagulants are needed with a lower risk of haematoma, wound drainage and blood loss.
When asked for three key things in implementing the fast-track approach, Dr Balatri put TXA top of his list: administering 1g at induction plus 1g before the patient leaves the recovery room and ‘ideally’ followed with another dose after two days. The next things on his list are locally infiltrated anaesthetic and a low-dose anticoagulant.
The relationship between bleeding and thromboembolism in TJA appears to be the aspect of blood management that most affects the risk of wound-healing complications.
Medical associations began issuing guidelines for preventing DVTs and thromboembolisms in general several years ago. The American College of Chest Physicians Evidence Based Clinical Practice (ACCP) issued very strict endpoints in 2008, checking for distal asymptomatic DVT with no emphasis on bleeding. A high-dose regimen of anticoagulants soon led to wound-healing complications in TJA: haematomas, bad for the wound but worse for functional outcome, a higher rate of residual pain, prolonged wound drainage and – in the worst cases – skin necrosis.
By 2012 the ACCP had recognised the problems and said ‘On balance, it was believed that the adverse consequences of a major postoperative bleeding event were approximately equal to those of symptomatic VTE.’28
The new guidelines for DVT prevention in primary joint arthroplasty allow a low-dosage regimen for anticoagulants plus the use of an intermittent pneumatic compression device (IPCD) where an early mobilisation protocol is enforced.
High-risk patients, for instance those with mechanical valves, atrial fibrillation or with a history of a previous DVT or pulmonary embolism, should follow a therapeutic dose-bridging regimen. That means even more anticoagulation therapy than in the previous guidelines.
Patients who require high-dose prophylaxis for cardiac or increased DVT risk must be regarded as at high risk of wound-healing complications.
Every day of wound drainage increased risk of infection by 42% following total hip
arthroplasty and 29% following a total knee arthroplasty…The solution lies in surgery (incision and drainage) or NPWT.
Dr Amerigo Balatri
Arthroplasty and spine: Single-patient use NPWT system (PICO◊) in primary THA/TKA: results of a prospective, randomised study
Mr Karlakki detailed the results of his prospective randomised study into the role of PICO◊ single-use NPWT system in preventing wound-healing complications.28
With 3000 joint replacements per year and a high bed occupancy rate in his own hospital, bed planning is crucial, and it is important to be able to predict patients’ length of stay. Determining factors include discharging wounds that affect mobilisation and increase the risk of superficial SSI, deep infection and revision surgery. Patients need to be discharged safely and on time.
The study was designed to test whether or not they could predictably improve wound exudates and send patients home early without increasing post-discharge complications. Its primary objectives, therefore, were to assess the effectiveness of single-use iNPWT dressing (PICO◊): levels of wound exudates and the effect on LOS. Secondary objectives were the number of dressing changes, wound complications and cost effectiveness.
A total of 220 patients enrolled in the study from October 2012–2013, all of whom were undergoing primary THR and TKR; patients were excluded where LOS was anticipated to be longer (for instance if they were scheduled for bilateral surgery or were on warfarin).
Patients must be self-sufficient when they are discharged and PICO◊ is a big help there: it is medically safe and keeps the wound safe, thereby allowing him to see many more patients in clinics rather than the hospital.
Results showed a statistically significant reduction of wound exudates with iNPWT and a significant reduction in post-discharge complications. There was also a statistically significant reduction in the number of dressing changes, although there was a large difference between the results of the three surgeons, one who did not stay while the dressing was applied and some of whose patients developed blisters. The PICO◊ dressing should not be stretched upon application and instead should be placed over the incision in order to minimise the potential of skin irritation.
NPWT reduces LOS demonstrably, although the difference is not statistically significant. iNPWT increases the predictability of discharge readiness because the wound becomes less of an issue, he said. There is a need for more evidence to investigate further the impact of PICO◊ on orthopaedic reconstruction.
Dr Antonio Mazzotti revealed the preliminary results of his prospective randomised study into the use of PICO◊ in revision total hip arthroplasty (THA) and total knee arthroplasty (TKA).
We know from the literature29 that the number of total hip and knee revision arthroplasties will increase exponentially in the next years, and the clinical and economic outcomes following primary and revision surgery are very different, in terms of complications during hospital stay, but also LOS and cost.
The aim of his study was to evaluate: the quality of wound healing with NPWT after prosthesis revision surgery (hip and knee); the patient’s pain and comfort during treatment; number of dressings per patient. Two groups were recruited with a diagnosis of prosthesis aseptic loosening, 50 with hip, 50 with knee. Each was subdivided into two groups of 25, one control and one experimental group. The single-use NPWT system PICO◊ was used in the experimental group. The ASEPSIS wound-scoring system was used at one week postoperatively by a blinded observer to evaluate the quality of wound healing.
Preliminary results showed that in the study group at day seven post-surgery, the surgical incision was dry. There were fewer local skin complications, and the ASEPSIS and VAS scores were lower in the experimental group than in the control group. The number of dressings and blisters were higher in the control group than in the experimental group.
The preliminary results showed fast wound healing with the result that patients could be discharged earlier without particular risks related to the wound, and iNPWT could become the optimal post-operative therapy in hip and knee revision surgery. After the presentation, he was asked about the statistical significance of his results, to which he replied that these are just trends and that he would like to enlarge the study and analyse the results further.
NPWT reduces length of stay demonstrably, although the difference is not statistically significant.
Mr Sudheer Karlakki
Preliminary results from a study into the use of PICO◊ in revision THA/TKA showed that iNPWT could become the optimal postoperative therapy in hip and knee revision surgery.
Mr Sudheer Karlakki
Arthroplasty and spine: NPWT for seroma prevention and surgical incision treatment in spinal fracture care
Dr Matthias Brem said he sees many traumatic spinal injuries in the large trauma centre at which he works in Nuremberg. Although he had seen increasing evidence for the use of iNPWT in orthopaedics recently, he had not seen much relating to spinal interventions, particularly after fractures.
All orthopaedic surgeons know there are large wounds following surgical intervention after spinal fracture, he said, so he wanted to investigate the use of iNPWT in their treatment. Dr Brem described his prospective RCT to examine iNPWT for seroma prevention and surgical incision treatment in spinal fracture care, and went on to reveal its findings.30
A total of 20 patients were randomised to iNPWT (PICO◊) and standard (dry wound) dressing, applied in OR over the wound area. The wound area under the skin is much bigger than the incision itself, said Dr Brem, so a bigger NPWT was used to cover the whole wound area and not just the incision in order to reduce oedema and seroma in the wound area. The wound was examined with ultrasound to measure for post-operative seromas or haematoma on days 5 and 10 post-surgery.
Total fluid collected in Redon drainages was 200ml less in the PICO◊ group than the standard dressing control group after two days. PICO◊ was kept on for five days, while several dressing changes were needed in the control group (10 minutes for PICO◊, 30 minutes for standard) and more material was needed for standard dressings.
There was no seroma of the wound after five days when PICO◊ was removed, but there was a small seroma in the control group. After 10 days, the ultrasound revealed a small seroma in the PICO◊ group (0.5 ± 1cm³); and in the standard dressing: (1.6 ± 2.6cm³).
There was a positive effect of iNPWT on the development of seroma after spinal surgery and on the development of wound secretion (a significantly lower amount in those patients who received PICO◊). There was also a significant reduction of nursing time and dressing material.
There was a positive effect of iNPWT on the development of seroma after spinal surgery and on the development of wound secretion…as well as a significant reduction of nursing time and dressing material.
Dr Matthias Brem
One delegate asked why Dr Brem had used a wider bandage in the spinal area. Professor Stannard returned to Dr Brem’s slides of the retraction and said: ‘Look at the wide area – there’s trauma from the trauma and there’s trauma from the surgeon. He’s applying it on the area he operated on, not just the incision. I think that’s really, really important.’
If the other proposed NPWT mechanisms are considered, it makes sense to consider covering the whole broader zone affected by the surgery. A good rule of thumb could be – how broadly do you retract? Look at the flaps underneath and try to cover most, if not all, of your flaps. This would make a very good study.
Professor Stannard replied to a question about NPWT use with amputation patients saying that he had used it with patients he thought were extremely high risk and it seemed to have worked, but it was case anecdote and not good science. He suggested it was a study gap to fill, because there are frequent problems with at least part of the incision line breaking down or developing necrosis, which has large implications on the end-bearing capability of the stump. PICO◊ can be used for an elective amputation, not for a traumatic one.
More published data are needed about how PICO◊ and incisional NPWT actually work; however, NPWT is considered an essential tool for preventing complications after orthopaedic surgery. NPWT is a vital tool for managing incisional wounds of complex patients with high risk of developing wound complications. It has been shown to reduce the length of hospital stay after hip- or knee-replacement surgery.
1. Wolcott R. PLoS Biol 2007;5:e3071.
2. Orgill DP, Bayer L. Plastic & Reconstructive Surgery 2011;127:105S–15S.
3. Stannard JP, et al. J Orthop Trauma 2012;26:37–42.
4. Stannard JP, et al. J Trauma 2006;60:1301–6.
5. Grauhan O, et al. J Thorac Cardiovasc Surg 2013;145:1387–92.
6. Ali M. International NPWT Expert Meeting. 2015 (www.smith-nephew.com/education/resources/video/2015/june/npwt-expertmeeting/wound-complications-in-lower-limbtrauma-clinical-experience-with-pico-singleuse-npwt-system; accessed 10 March 2016).
7. Nicholson Roberts TC, Berry RD. Continuing Education in Anaesthesia, Critical Care & Pain 2012;12:186–9.
8. Penn-Barwell JG, et al. Eplasty 2011;11:e35.
9. Penn-Barwell JG, et al. J Bone Joint Surg 2011;93:51 2.
10. Gomoll AH, Harris LA. J Orthop Trauma 2006;20:705–9.
11. Taylor CJ, et al. J Hand Surg 2011;36A:1848–51.
12. Surveillance of surgical site infections in NHS hospitals in England 2011–12
(Public Health England, DoH publication) (www.gov.uk/government/uploads/system/uploads/attachment_data/file/364326/SSI_annual_report_England_2011_12.pdf; accessed 4 November 2015).
13. Health and Social Care Information Centre. Finalised Patient Reported Outcome Measures (PROMs) in England. April 2012 to March 2013. Published 14 August 2014.
14. Patel VP, et al. J Bone Joint Surg Am 2007;89:33–8.
15. National Joint Registry for England, Wales and Northern Ireland. 11th Annual
Report 2014 (www.njrreports.org.uk/2013; accessed 3 November 2015).
16. Jenks PJ, et al. J Hospital Infec 2014;86:24–33.
17. Karlakki S, et al. Bone Joint Res 2013;2:276–84.
18. Stannard JP, et al. Ostomy Wound Manage 2009;55:58–66.
19. Reddix RN Jr, et al. Am J Orthop 2009;38:446–9.
20. Suh H, et al. Negative pressure wound therapy on closed surgical wounds with dead space: animal study using a swine model. Ann Plast Surg 2014; 4 July epub ahead of print (doi: 10.1097/SAP.0000000000000231).
21. Reddix RN, et al. J Surg Orthop Adv 2010;19:91–7.
22. Karlakki S. International NPWT Expert Meeting (www.smith-nephew.com/education/resources/video/2015/june/npwt-expertmeeting/
single-patient-use-npwt-system-picoin-primary-thatka-results-of-a-prospectiverandomized-study/; accessed 10 March 2016).
23. Pauser J, Nordmeyer M, Biber R, et al. Incisional NPWT hemiarthroplasty:
femoral neck fracture. Int Wound J 14 August 2014, epub ahead of print
24. Kehlet H. Br J Anaesth 1997;78:606–17.
25. Pinto PR, et al. PLoS ONE 2013;13:e73917.
26. Hansen E, et al. Clin Orthop Relat Res 2013;4714:3230–6.
27. Husted H, et al. Acta Orthopaedica 2014;85:548–55.
28. Balatri A. International NPWT Expert Meeting (www.smith-nephew.com/education/resources/video/2015/june/npwt-expertmeeting/
approach/; accessed 10 March 2016).
29. Kurtz S, et al. 2005 to 2030. J Bone Joint Surg Am 2007;89:780–5.
30. Nordmeyer M, et al. Negative pressure wound therapy for seroma prevention and surgical incision treatment in spinal fracture care. Int Wound J 2015; 30 April epub ahead of print (doi: 10.1111/iwj.12436).