This is a plain English summary of an original research article
Negative pressure wound dressings are neither more nor less effective than standard wound dressings for severe open fractures of the lower leg. Any difference between groups was neither clinically important nor statistically significant. The outcomes included self-rated disability at one year, quality of life and deep surgical site infections at one month which occurred in around 7-8% in each group.
Open fractures of the leg, where the broken bone is exposed by the original injury or has burst through the skin, are prone to infection. Usually, the wound is thoroughly cleaned, damaged tissue removed (debridement), the bone stabilised and a standard dressing applied. Negative pressure wound therapy requires a special dressing and an additional vacuum pump. This removes surplus blood and fluid from the wound, which was expected to improve the chances of healing and reduce deep tissue infections.
The results of this NIHR-funded trial suggest that this more expensive option offers no significant gains for patients.
Why was this study needed?
Open fractures of the lower limbs are particularly vulnerable to infection, with some estimates running as high as 27%. In more severe cases the wound cannot be closed, and a dressing is applied to cover it.
Use of negative pressure wound dressings has become widespread despite a lack of evidence of their effectiveness. Before this trial, there had been only one randomised controlled trial of 59 people with open fractures. It found that fewer people developed deep infections with negative pressure wound therapy, occurring in two people compared to seven with standard dressings.
This trial aimed to assess whether they improved healing rates, reduced infection or had any impact on quality of life.
What did this study do?
The WOLLF randomised controlled trial compared outcomes between 226 people who received negative pressure dressings and 234 who received standard dressings. All had a severe open fracture where the wound was not stitched together.
The main outcome was the self-reported Disability Rating Index score at 12 months, a scale 0 to 100 with higher scores indicating more disability. Eight points represents a clinically important change equivalent to the difference between the ability to climb stairs or run with “some difficulty” compared with doing so with “great difficulty”.
Standard treatment varied in terms of the specific dressing used and represented usual practice. The pragmatic trial was based at 24 major trauma centres in the UK, so is likely to be representative of UK practice.
What did it find?
There were no clinically important differences in disability, deep infections or healing.
- The mean Disability Rating Index score at 12 months was 45.5 in the negative pressure group and 42.4 in the standard treatment group (adjusted mean difference [aMD] -3.9, 95% confidence interval [CI] -8.9 to 1.2).
- Deep surgical site infection at 30 days occurred in 16 (7.1%) people in the negative pressure group and 19 (8.1%) people in the standard treatment group (difference 1%, 95% CI -4.2% to 6.3%). By six weeks, the wound had healed in 52% of the negative pressure group and 51.7% of the standard treatment group (odds ratio 1.0, 95% CI 0.6 to 1.6).
Quality of life was similar in both groups throughout, and by 12 months:
- Average scores on the EuroQol 5-dimensions questionnaire (range ‑0.59, worse than death to 1.0, perfect health) were 0.55 in the negative pressure group compared with 0.56 in the standard treatment group (aMD 0.01, 95% CI -0.06 to 0.07);
- For the Short form-12 Physical Component Score (range 0 to 100, with higher score indicating better health), the negative pressure group average score was 32.2 compared with 32.7 in the standard treatment group (aMD 0.4, 95% CI -3.0 to 3.8);
- Scores on the Short form-12 Mental Health Component Score (range 0 to 100, with higher scores indicating better health) were 44.7 in the negative pressure group compared with 44.3 in the standard treatment group (aMD -0.2 (95% CI, -2.1 to 1.6).
What does current guidance say on this issue?
The NICE 2016 guideline on complex fractures previously stated that for open fractures where debridement has taken place, but the wound remains uncovered, negative pressure wound therapy can be utilised. However, this recommendation is being revised in 2018 to include new evidence from the findings of the WOLFF trial.
What are the implications?
The findings from this trial have been incorporated into an updated Cochrane review, plus two other small trials completed in 2016. It is the only one that provides 12-month outcomes for disability and quality of life and indicates that the more expensive negative wound pressure dressings are no better. The pooled data shows uncertainty about whether negative wound pressure reduces deep infections for open wounds following open fractures. These findings are likely to be seen as important for orthopaedic practice.
Not offering this treatment would potentially save money for use on other therapies and help simplify the care pathway. Negative pressure dressings are used in other surgical contexts, and these might be suitable for a similar study.
Citation and Funding
Costa ML, Achten J, Bruce J, et al; UK WOLLF Collaboration. Effect of negative pressure wound therapy vs standard wound management on 12-month disability among adults with severe open fracture of the lower limb: the WOLLF randomized clinical trial. JAMA. 2018;319(22):2280-88.
This project was funded by the National Institute for Health Research Health Technology Assessment Programme (project number 10/57/20).
Stannard JP, Volgas DA, Stewart R, et al. Negative pressure wound therapy after severe open fractures: a prospective randomized study. Journal Orthop Trauma. 2009;23(8):552‐7.
Iheozor-Ejiofo Z, Newton K, Dumville J, et al. Negative pressure wound therapy for open traumatic wounds. Cochrane Database Syst Rev. 2018;(7):CD012522.
NICE. Fractures (complex): assessment and management. NG37. London: National Institute for Health and Care Excellence; 2016 (updated 2017).
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