Use of negative-pressure wound therapy (NPWT) is growing in the management of complex wounds as well as foot and ankle surgery. Researchers from Rush University Medical Center in Chicago and Wake Forest Baptist Health Center in North Carolina recently published a review of the evidence for NPWT in Foot & Ankle International. Their findings related to diabetic foot and neuropathic ulcers are excerpted here.
While its mechanism of action is not fully understood, NPWT is thought to foster healing via changes in growth factor expression, micro- and macro-deformation, blood flow, exudate removal, and bacterial concentration within the wound bed (see Table). Furthermore, the authors note that NPWT is believed to enhance wound healing by physically and biologically altering the wound bed to induce a cellular and tissue response to shearing forces created by the sub-atmospheric environment.
Diabetic and Neuropathic Foot Ulcers
NPWT may preserve limbs in patients with diabetic or neuropathic foot ulcers by diminishing their size to allow subsequent coverage procedures.
- Zhang et al (2014) performed a recent meta-analysis including 8 studies and 669 patients to determine the efficacy and safety of NPWT for diabetic foot ulcers (Level II evidence). The use of NPWT compared to treatment without NPWT had a relative risk (RR) of 1.52 (95% confidence interval [CI] = 1.23-1.89; P < .001) for healing, a greater reduction in the area of the ulcer (standardized mean difference = 0.89 cm2, 95% CI = 0.41-1.37; P = .003), and a shorter time to heal (standardized mean difference = −1.1 months, 95% CI = −1.83 to −0.37; P = .003). NPWT resulted in significantly fewer major amputations (RR = 0.14, 95% CI = 0.04-0.51; P =.003), but no significant difference in the rate of minor amputations.
- Goudie et al (2012) reported on limb salvage through NPWT and administration of recombinant platelet-derived growth factor after partial calcanectomy for large (>4-cm) heel ulcers in diabetic patients. Complete healing was achieved within 6 months in 20 of 21 patients, and the authors reported a limb salvage rate of 76% at 2 years (Level IV evidence).
- Stone et al (2011) reviewed the use of NPWT with resection arthroplasty and external fixation for first metatarsophalangeal (MTP) joint neuropathic ulcers (Level IV evidence). In all cases, the wound was left open and NPWT was initiated on the second day after surgery. At a median follow-up of 38 months, 6 patients went on to amputation, while the remaining 10 had resolution of their ulcer. The authors concluded that this approach was a safe and effective alternative to amputation.
- In a small prospective case series, Nather et al (2010) found NPWT decreased the size of foot ulcers between 18.4% and 41.7% and all wounds healed, the majority with an additional procedure (Level IV evidence). Nine patients healed subsequently with split-thickness skin grafting and 2 closed by secondary intention. Furthermore, all wounds achieved microbial clearance and complete wound granulation at a mean of 33 days.
Poor limb or local perfusion may limit the success of NPWT.
- Clare et al (2002) concluded that NPWT was an acceptable option, but cautioned its use for ulcers in patients with severe peripheral vascular disease (Level IV evidence; Hermans et al, 2013). Although 82% of the wounds in 17 patients healed successfully by a mean of 8.2 weeks, the authors reported the 3 patients who failed treatment had severe peripheral vascular disease.
- Sundby et al (2016) reported on 4 patients with lower-leg ischemia and complex leg ulcers managed with portable NPWT applied in home (Level IV evidence). This device cycled a negative-pressure wound environment by alternating closing or venting the system to air. After 8 weeks, 1 ulcer healed whereas the other 3 had not. The evidence supports the use of NPWT for diabetic and neuropathic ulcers; however, the adequacy of perfusion to the limb or local tissue must weigh in the decision to initiate treatment (grade B recommendation).
- While NPWT may be applied to an open or closed wound, the authors caution that certain wounds and clinical circumstances may respond differently to NPWT, require disparate plans of care, and have dissimilar rates of infection or failure of treatment. They conclude that further studies are needed to determine the effects and define the role of NPWT in the management of foot and ankle wounds.
Source: Kunze KN, Hamid KS, Lee S, Halvorson JJ, Earhart JS, Bohl DD. Negative-pressure wound therapy in foot and ankle surgery. Foot & Ankle Int. 2019;Dec 13: 1071100719892962. doi: 10.1177/1071100719892962. [Epub ahead of print] Copyright © 2019. Reprinted with permission from SAGE Publications. All rights reserved.