Tendon and/or bone exposure commonly occurs in the foot and ankle region after acute trauma 1. The conventional treatment method used for these uncovered, open wounds in the foot and ankle is skin grafting after the formation of healthy granulation tissue by wet dressing 2. However, the duration of treatment may be prolonged, and patients may experience severe pain during dressing changes 3. Furthermore, it is difficult to form healthy granulation tissue by simple wet dressing, when a tendon, bone, or implant is exposed. Accordingly, free flap surgery is often required, which requires substantial effort and introduces the issue of donor site morbidity 4.

Negative pressure wound therapy (NPWT) was first described by Argenta and Morykwas 2. This technique can be used to cover exposed bone or soft tissue defects without frequent dressing changes, and reduces chronic edema and increases local blood supply, which enhances the formation of healthy granulation tissue. Several reports have been issued on the application of NPWT to soft tissue defects of the extremities, abdomen and chest 56. However, reports regarding its use in the foot and ankle region are limited, though in this region tendon and bone exposures frequently occur after external injury or due to chronic ulcerative disease. The purpose of this study was to determine how NPWT helps healing and whether the technique can reduce the need for flap surgery for the treatment of acute or chronic open wounds in the foot and ankle region.

Over the four year period from 2003 to 2006, 16 patients (12 males and 4 females) with soft tissue injuries in the foot and ankle region were treated with an NPWT device (V.A.C.,^® Vacuum Assisted Closure, KCI, San Antonio, United States) at the authors' institute. All 16 patients were followed for more than 12 months (mean: 19 months, range: 13–39 months). Mean patient age was 32.8 (range: 3–67). All patients had experienced an acute injury, caused by either a traffic accident in 12, a falling from a height in 2, and a crush injury in 2. Wound locations were on the medial side of the ankle in 3 cases, the lateral side of the ankle in 1 case, and of the dorsum of the foot in 12 cases. All patients had at least one tendon or bone exposed at the initiation of NPWT, and four had an associated infection (Table 1).

The mean duration of therapy was 18.4 days (range, 11–29 days), and dressings were changed 4.5 times on average. Mean wound size at treatment initiation was 56.4 cm² (9–151 cm²), and this reduced to 42.9 cm² (4–81 cm²) at treatment completion, an average wound area reduction of 24%. Fifteen of the 16 patients achieved an improved wound status, and in these exposed tendons or bone was covered with healthy granulation tissue (Figures 1, 2). After NPWT, skin grafting was performed to cover granulation tissue in 15 cases (a split-thickness skin graft in 14 cases and a full-thickness skin graft in 1 case). One patient experienced treatment failure, and required a free flap to cover exposed bone and tendon. The average wound grade was 2.69 at the start of treatment, and 1.13 at the end of treatment.

No complication occurred that could be directly attributed to NPWT, such as, a deep infection or bleeding. In terms of minor complications, four patients experienced itchiness of skin in the region of NPWT application. In addition, 2 patients experienced scar contractures in grafted areas, which were rescued using a releasing procedure.

Traumatic injuries around the foot and ankle are often associated with significant skin loss, which results in the exposure of tendons, bone, or hardware, and associated wound-management difficulties. These injuries are similar in many ways, to chronic ulcerative lesions of the foot associated with ischemic diseases, such as, diabetes mellitus. The rapid formation of granulation tissue and blood vessels are essential for the healing of these wounds. Traditionally, frequent wet dressing changes (3–4 times/day) are used to treat such cases, but this treatment is protracted and painful 37. Furthermore, interstitial fluid from open wounds reduces local blood supply and disturbs wound healing due to its collagenase and metalloproteinase constituents 89. From this viewpoint, NPWT is highly effective at clearing interstitial fluid, and in the majority of our patients, wounds were covered with healthy granulation tissue after 4.5 sponge changes, without additional flap surgery. DeFranzio⁵ also reported that NPWT enhances rapid granulation formation in over 80% of patients as compared with a simple wet dressing. Furthermore, it has been well reported that NPWT provides a continuous physical stimulus that enhances the formation of new vessels and granulation tissues 1011.

Soft tissue defects in the foot and ankle region usually require local or free flap surgery when a skin graft procedure is not applicable due to limited granulation tissue formation¹. A split-thickness skin graft is not recommended for wounds with exposed bone or neurovascular structures, or for wounds involving the weight-bearing surface of the foot 12. In a comparative study of traditional dressings and NPWT for lawnmower injuries of the lower leg 13, the need for free flap surgery was found to be decreased by 30%. A remarkable reduction in the requirement for secondary soft tissue operation is believed to be a big advantage of NPWT 14. Dedmond 15 also reported that wounds of grade 3 with an accompanying open tibial fracture healed without the need for a secondary soft tissue operation, such as, a free flap. In the present study, the severities of open wounds were noticeably reduced after NPWT; only one patient needed a free flap to cover exposed bone and tendon.

The prevention of deep infection is essential during the treatment of soft tissue defects, and simple wet dressing may be inadequate in this context, because wounds are inevitably exposed to the atmosphere. On the other hand, NPWT not only seals open wounds but evacuates hematomas, exudates, and possible pathogens by the application of negative pressure 101617. Furthermore, it has been reported that NPWT is effective at treating deep infections 18. In the present study, no case of infection during the treatment period occurred. Accordingly, we consider that NPWT probably also reduces soft tissue defect infection rates.

Some technical difficulties have been reported when NPWT was used to treat foot wounds 19, but we did not encounter these problems. In terms of complications, we did encounter 2 cases of skin graft scar contractures, which can reduce foot function. Successful scar release was achieved in these two cases. But, in certain cases, flap surgery may be considered to prevent scar contractures 20, instead of NPWT.

This study has several limitations that require consideration, namely, that the size of data is small, and there was no control group, which reduced objectivity. We suggest that a prospective randomized multicenter trial be undertaken to determine the merits of NPWT for the treatment of soft tissue defects of the ankle and foot. However, based on the results of previous studies on its use for the treatment of other injuries at other locations, it appears that NPWT plays a significant role in the formation of granulation tissue and in the prevention of infection 21.

Our results add to growing evidence that NPWT is a useful adjunctive treatment for open wounds around the foot and ankle. In the present study, it was found to facilitate the rapid formation of granulation tissue, to shorten healing time, and to reduce remarkably the need for additional soft tissue reconstructive surgery.

The authors declare that they have no competing interests.

CWO, HJL carried out concept design, patient recruitment and follow-up, data collection and analysis, and manuscript writing. JWK carried out literature search and data analysis. WKM carried out data collection, patient follow up, data analysis and manuscript writing. OJS, JKO, BCP, JCI conceived of the study, and participated in its design and coordination. All authors read and approved the final manuscript for publication.