Diabetic foot ulcers cause substantial illness, hospital use, and lower-limb amputation. Between 19% and 34% of people with diabetes are likely to develop a foot ulcer in their lifetime (Armstrong et al., 2017). Ulcers often recur after healing. About 40% of patients have a recurrence within one year, and 65% within five years (Armstrong et al., 2017). NPWT for diabetic foot ulcers is available in many countries, but its benefit remains debated. This article reviews the randomised trial, systematic review, and guideline evidence. It then sets out the clinical conditions under which the evidence supports use.
What the randomised trials show
Two randomised trials provide most of the direct evidence for NPWT in diabetic foot wounds. Both report faster or greater healing with NPWT. Each is a single study, so the findings need careful interpretation.
Surgical wounds after partial foot amputation
The Diabetic Foot Study Consortium randomised 162 patients with partial foot amputation wounds across 18 centres over 16 weeks (Armstrong et al., 2005). Eligible wounds extended up to the transmetatarsal level, and patients needed adequate perfusion (Armstrong et al., 2005). Time to complete closure was faster with NPWT (P = 0.005). Adverse events were similar between groups, and wound infection was the most common (Armstrong et al., 2005). The authors described fewer re-amputations as a possible benefit, not a demonstrated one (Armstrong et al., 2005).
Chronic diabetic foot ulcers
Blume and colleagues randomised 342 patients with diabetic foot ulcers to NPWT or advanced moist wound therapy, which mainly uses hydrogels and alginates (Blume et al., 2008). Complete closure meant full skin coverage without drainage or a dressing requirement (Blume et al., 2008). By day 112, 43.2% of NPWT-treated ulcers had closed, compared with 28.9% of moist-therapy ulcers (P = 0.007) (Blume et al., 2008). The median time to closure with NPWT was 96 days (95% CI 75.0 to 114.0) (Blume et al., 2008). Secondary amputations were fewer with NPWT (P = 0.035). Complications such as infection did not differ at six months (Blume et al., 2008). The absolute difference in closure was 14.3 percentage points, calculated from the reported counts.
A P value below 0.05 suggests that a result is unlikely under no true effect. It does not show that the difference matters to patients. Closure is a surrogate outcome. It stands in for results that matter more to patients, such as avoiding amputation or infection and maintaining function.
Guideline positions
The International Working Group on the Diabetic Foot (IWGDF) updated its wound-healing guideline in 2023 (Chen et al., 2023). Its recommendations depend on wound type:
- Post-surgical foot wounds: consider NPWT as an adjunct to standard care. This is a conditional recommendation based on low-certainty evidence (Chen et al., 2023).
- Non-surgical diabetic foot ulcers: do not use NPWT as an adjunct to standard care. This is a strong recommendation based on low-certainty evidence (Chen et al., 2023).
The guideline states that NPWT may reduce time to healing after surgery. It found insufficient evidence that NPWT shortens healing time in chronic ulcers (Chen et al., 2023). All recommendations apply when best standard care alone has failed to heal the ulcer. Best standard care includes sharp debridement (removal of dead tissue with instruments), offloading, revascularisation (restoring blood flow) where indicated, and treatment of infection (Chen et al., 2023). The guideline also notes that NPWT may require moderate to high costs, which may reduce equity where access is limited (Chen et al., 2023).
Limitations and conflicting evidence
Several limitations affect how far these findings can be applied.
- Small and short trials. The Cochrane trials enrolled 15 to 341 participants and followed patients for 4 to 16 weeks (Liu et al., 2018).
- Risk of bias. The IWGDF judged all NPWT studies to be at moderate or high risk of bias (Chen et al., 2023).
- Industry funding. Two included trials were funded by an NPWT manufacturer (Liu et al., 2018).
- Limited applicability to poorly perfused wounds. The surgical trial required adequate perfusion (Armstrong et al., 2005). The IWGDF found insufficient evidence for chronic ulcers (Chen et al., 2023).
- Few patient-important outcomes. The IWGDF identified no studies reporting mortality. The Cochrane review found no evidence on quality of life or cost-effectiveness (Chen et al., 2023; Liu et al., 2018).
Conflicting findings on amputation
The Cochrane analysis suggests fewer amputations with NPWT in foot ulcers (Liu et al., 2018). The IWGDF found no difference in amputation in the studies with the lowest risk of bias, although those studies were relatively short (Chen et al., 2023). The conflict is unresolved, and the certainty of evidence is low on both sides.
Statistical significance is not the same as clinical importance. Healing is a useful outcome, but it differs from outcomes that matter most to patients, such as amputation, infection, and quality of life. The IWGDF calls for better trials, including those with health-economic analysis (Chen et al., 2023).
Clinical application
NPWT is supported in defined post-surgical situations. It is not a routine treatment for every diabetic foot ulcer.
When NPWT may be considered
- Post-surgical diabetic foot wounds, such as wounds after partial foot amputation or surgical debridement (Chen et al., 2023; Armstrong et al., 2005).
- Wounds that have not healed with best standard care, where trained staff and resources are available (Chen et al., 2023; Apelqvist et al., 2024).
When NPWT should not be used
- Non-surgical diabetic foot ulcers, as an add-on to standard care (Chen et al., 2023).
- Untreated osteomyelitis or malignancy in the wound (Int Wound J, 2013).
- Exposed blood vessels, anastomotic sites, organs, or nerves, where the foam must not contact them directly (Int Wound J, 2013).
- Non-enteric or unexplored fistulas (Int Wound J, 2013).
- Necrotic tissue with eschar, until debridement is complete (Int Wound J, 2013).
- Sensitivity to silver, for silver-containing foams (Int Wound J, 2013).
- Wounds with inadequate perfusion, because the supporting surgical trial required adequate perfusion (Armstrong et al., 2005).
Practical requirements
Before starting NPWT:
- Complete sharp debridement and treat infection first (Chen et al., 2023).
- Confirm adequate perfusion, and offload pressure from the wound (Armstrong et al., 2005; Chen et al., 2023).
- Confirm that trained staff can set up the device, change dressings, and troubleshoot alarms (Apelqvist et al., 2024).
During therapy:
- Apply negative pressure, usually between 75 and 125 mmHg (millimetres of mercury) (Apelqvist et al., 2024).
- Change dressings about every two to three days (Apelqvist et al., 2024).
- Respond to alarms and device faults promptly (Apelqvist et al., 2024).
For home care:
- Provide patient and caregiver education, clear discharge routines, and remote monitoring where available (Apelqvist et al., 2024).
Training should begin before NPWT starts and continue over time (Apelqvist et al., 2024).
VACUHEAL position
The evidence supports NPWT in defined situations, most clearly after foot surgery. It does not support routine use for every ulcer. The guideline positions and trial populations point to the same practical conditions: careful wound selection, perfusion and infection managed first, and trained staff. This is why protocol and support matter. VACUHEAL's Scientific Office provides clinical support and training for hospital and home-care teams.
Frequently asked questions
Does NPWT heal diabetic foot ulcers?
NPWT may increase the proportion of diabetic foot ulcers that heal, but the certainty of evidence is low (Liu et al., 2018). Guideline support is limited to post-surgical foot wounds, where healing time may be reduced (Chen et al., 2023). Guidelines advise against NPWT as an add-on for non-surgical ulcers (Chen et al., 2023).
Is NPWT recommended after foot surgery?
The IWGDF gives a conditional recommendation to consider NPWT as an adjunct to standard care for post-surgical diabetic foot wounds (Chen et al., 2023). The recommendation rests on low-certainty evidence and applies when standard care alone has not healed the wound (Chen et al., 2023).
Does NPWT reduce amputation?
The evidence is uncertain. A pooled analysis of three studies suggested lower amputation risk, but the certainty is low (Liu et al., 2018). The IWGDF found no amputation difference in the studies with the lowest risk of bias, which were relatively short (Chen et al., 2023).
What pressure is used?
Usual settings are 75 to 125 mmHg, with exceptions up to 200 mmHg in selected cases (Apelqvist et al., 2024). The Cochrane review could not determine whether 75 and 125 mmHg differ, because only one 40-participant study compared them (Liu et al., 2018).
Clinicians who want to discuss case selection, protocols, or the evidence in this review are invited to contact the VACUHEAL Scientific Office. Scientific discussion and clinical support are available for hospital and home-care teams.
References
- Liu Z, Dumville JC, Hinchliffe RJ, Cullum N, Game F, Stubbs N, Sweeting M, Peinemann F. Negative pressure wound therapy for treating foot wounds in people with diabetes mellitus. Cochrane Database of Systematic Reviews. 2018;(10):CD010318. doi:10.1002/14651858.CD010318.pub3. Cochrane record
- Armstrong DG, Boulton AJM, Bus SA. Diabetic foot ulcers and their recurrence. New England Journal of Medicine. 2017;376(24):2367–2375. doi:10.1056/NEJMra1615439
- Armstrong DG, Lavery LA; Diabetic Foot Study Consortium. Negative pressure wound therapy after partial diabetic foot amputation: a multicentre, randomised controlled trial. The Lancet. 2005;366(9498):1704–1710.
- Blume PA, Walters J, Payne W, Ayala J, Lantis J. Comparison of negative pressure wound therapy using vacuum-assisted closure with advanced moist wound therapy in the treatment of diabetic foot ulcers: a multicenter randomized controlled trial. Diabetes Care. 2008;31(4):631–636. doi:10.2337/dc07-2196
- Chen P, Campillo Vilorio N, Dhatariya K, et al. Guidelines on interventions to enhance healing of foot ulcers in people with diabetes (IWGDF 2023 update). Diabetes/Metabolism Research and Reviews. 2024;40(3):e3644. Epub 2023. PubMed record
- Apelqvist J, Fagerdahl A, Téot L, Willy C. Negative pressure wound therapy: an update for clinicians and outpatient care givers. EWMA Document. Journal of Wound Management. 2024;25(2 Suppl 1):S1–S56. doi:10.35279/jowm2024.25.02.sup01
- Negative pressure wound therapy: past, present and future. International Wound Journal. 2013;10(Suppl 1):15–19. doi:10.1111/iwj.12170. [Author list to be confirmed against the journal record before publication.]
In-text citations use author and year. The label Int Wound J, 2013 refers to reference 7.
