Long‐term follow‐up of negative pressure wound therapy with instillation: a limb salvage procedure?

Abstract

Negative pressure wound therapy (NPWT) is a treatment to reduce oedema, stimulate granulation tissue formation, remove wound exudate and diminish wound area, thus preparing it for secondary healing, skin grafting or coverage with flaps. The association of instillation to NPWT (NPWTi) is a new method for treating severe wounds, in particular, limb lesions at high risk for amputation. This therapy helps to deliver instillation fluid automatically into the contaminated wound, before application of negative pressure. These steps, repeated cyclically, help to remove infectious material, leading to a better moist environment, a necessary condition for wound healing. We report our experience of treating three patients with complex wounds and associated noble structure exposition conservatively with NPWTi and flap coverage. In a long‐term follow‐up (5 years), we were able to achieve a stable surgery reconstruction on preserved limbs, without evidence of chronic infection and other sequelae or complications. Despite the fact that our experience is limited , as it is based on only a few cases, it suggests how NPWTi could be considered useful in a conservative approach to the treatment of acute complex wounds of the lower extremities. In these patients with high risk of amputation, a long‐term follow‐up becomes fundamental in order to evaluate wound bed status after NPTWi.

Introduction

Negative pressure wound therapy (NPWT) is a treatment to reduce oedema, stimulate granulation tissue formation, remove wound exudate and diminish the wound area, thus preparing it for secondary healing, skin grafting or coverage with flaps.

This therapy, first proposed by Argenta and Morykwas in 1997, is based on negative pressure effects on the wound healing process (in the range of 75–125 mmHg) 1. NPWT is able to reduce wound healing time in comparison to advanced dressings because of its ability to increase granulation tissue growth 2.

This process allows achieving complete healing faster, by using different techniques to cover the prepared wound: skin grafts, myocutaneous flaps, fasciocutaneous flaps or other conservative treatments such as advanced dressings 3, 4.

Recently, a new device combining negative pressure and fluid instillation was introduced for wound infection treatment. Negative pressure wound therapy with instillation (NPWTi) was first described by Fleischmann et al. in 1998 5, 6. In 2009, Timmers et al., reported successful results in treating posttraumatic osteomyelitis with NPWTi 7.

NPWTi allows a combination of NPWT and timed and intermittent delivery of topical solutions. The NPWTi unit has an additional instillation tube that connects the dressing with an infusion bag containing the solution. Separate vacuum and instillation clamps open and close at set intervals, with the automated delivery of the solution (instillation phase) followed by a hold time for penetration and incubation (hold phase), and resumption of negative pressure for extraction of the solution from the wound bed and application of NPWT (vacuum phase). The three phases together form a therapy cycle 8.

For the instillation phase, a wide range of fluids are proposed, with the aim of their penetrating into the wound bed through the foam [antibiotics, antiseptics and anaesthetics 7], but currently no precise indications about the best solution to instill 9 are available in the literature.

Because of its characteristics, NPWTi could be an optimal answer to specific problems in complex wounds. In fact, acute traumas of the lower limbs can cause complex functional damage with associated skin loss, and soft tissue damage with exposed tendons, joints, bones and/or vessels, which will require a multidisciplinary approach 10.

One of the major challenges is the decision on whether to perform a limb salvage procedure or proceed with an acute amputation, as a result of the severity of the injury. In recent years, salvage has replaced amputation as the primary treatment for severe limb trauma in many trauma centres 11.

In the last two decades, medical and surgical developments have improved the ability to reconstruct a severely injured leg conservatively. In the orthopaedic trauma literature 12, 13, an extensive debate is ongoing regarding the decision whether to amputate or reconstruct a severely injured leg.

For high‐energy injuries to limbs, extremity salvage surgery should then be considered as the first option.

The decision to amputate a segment is challenging, given that amputation is irreversible. We should consider the fact that amputation causes major problems including functional loss, image problems and mood disorders. Comorbidities can be related to amputation level, above all causing repeated stump problems, phantom limb pain and comfort troubles (upper knee prosthesis) 14. Moreover, learning to walk with a prosthesis is a laborious task, requiring cognitive ability, conditioning and balance.

On the basis of these considerations, a conserved extremity can provide the patient with a good adaptation to social and daily life when compared with amputation, even in the presence of functional loss 15.

At the same time, when treating exposed fractures, early surgical procedures of bone coverage are usually mandatory, so as to prevent further contaminations. When the patient's general conditions are ideal, an immediate coverage with conventional and microsurgical flaps may be indicated. However, this approach is not always possible in patients requiring intensive care, such as those with severe multiorgan involvement or those in whom the management of limb wounds is secondary to life‐threatening problems; in these cases, definitive soft tissue coverage is usually delayed. When wound contamination is still present, bone vitality after surgical debridement is uncertain and there is the possibility of a progressive tissue necrosis, orthopaedic surgeons may sometimes expressly request delaying the definitive coverage until bone quality revaluation is carried out, to go for a conservative approach (limb salvage) 16.

In all these specific cases, NPWTi can provide intermittent wound irrigation and fluid removal together with negative pressure cycles in order to clean the wound and generate valid granulation tissue. Moreover, it also prevents secondary wound contaminations, thanks to its occlusive dressing. At the same time, NPWTi permits multispecialistic evaluations (by a plastic surgeon, orthopaedic, infectivologist, etc.) of the wound healing process step by step so as to achieve a definitive and stable reconstruction, acting as a bridge between debridements to prepare the wound bed for closure or grafting.

Even though other successful cases treated with NPWTi are reported in the literature, the evaluation of long‐term follow‐up results is of paramount importance in order to define surgical reconstruction quality together with the absence of secondary infections. To the best of our knowledge, this is the first paper reporting long‐term results after this procedure.

In selected cases, where a high risk of amputation was present, we had a positive experience using NPWTi and subacute surgery, which was confirmed in a long‐term follow‐up (5 years) showing a stable reconstruction, without any secondary infections.

Case reports

Case 1

Female, 45 years old, airscrew boat trauma victim (Figure 1).

Figure 1.

A 45‐year‐old female victim of airscrew boat trauma. (A) Medial region of the right knee necrosis. (B) Medial femoral condyle and knee joint exposition after surgical debridement. (C) Valid granulation tissue after 14 days of negative pressure therapy with instillation. (D) Six‐year follow‐up after reconstruction with tensor fasciae latae patch over the joint covered with medial gastrocnemius muscle flap and autologous meshed 1:2 skin graft.

She was transferred from another out‐of‐region hospital 15 days after the trauma, with a full‐thickness necrosis in the medial region of the right knee. The knee was red and warm, blood samples demonstrated white blood cell enhancement and fever was present.

We decided to perform an urgent surgical debridement in order to remove necrotic tissue, control infection and check the wound depth. The debridement exposed the medial femoral condyle, partly destroyed in the trauma and the open knee joint. Collaboration with orthopaedics was begun immediately in order to manage the treatment of bones, joint and skin successfully. During the same first surgical procedure, orthopaedics positioned external fixators in order to immobilise the joint in a position where it was stable.

Intraoperative bacterial swabs tested positive for Enterococcus faecalis; therefore, on the basis of the antibiogram, a systemic antibiotic intravenous therapy was started.

The patient was also considered at high risk for amputation because wound contamination did not allow immediate reconstruction and coverage. Together with the orthopaedics, we decided on a conservative approach.

NPWTi was positioned on the wound, with the cycle of aspiration at −125 mmHg for 4 hours, instillation of saline solution for 20 seconds and soaking for 2 minutes. Change of dressing was performed every 5 days at the patient's bed, without the requirement of anaesthesia. After 15 days, NPWTi produced a valid granulation tissue and intra‐articular swabs returned negative results.

At this point, at day 21 after admission, we decided to perform a stable reconstruction: a tensor fasciae latae patch was used to close the knee joint; then the joint was covered with a medial gastrocnemius flap and autologous meshed grafts. The take of flap and grafts was good, there were no complications and after 3 months the external fixators were removed.

A six‐and‐a‐half‐year follow‐up showed limited knee joint excursion (about 20 degrees), stable soft tissue reconstruction and no secondary infection. No further plastic surgery procedures were required.

Case 2

Male, 20 years old, with a high‐energy trauma injury after a car accident (Figure 2).

Figure 2.

A 20‐year‐old male victim of high‐energy car accident. (A) Front‐medial region of right knee complex wound with joint exposition. (B) Florid granulation tissue after 35 days of negative pressure therapy with instillation. (C) Reconstruction with medial gastrocnemius muscle flap covered with meshed 1:2 graft after 45 days. (D) Four‐year follow‐up.

The first therapeutic approach was in the intensive care unit, because of the complexity of the trauma.

In the plastic surgeon's opinion, the patient had a deep and complex wound in the frontal and medial region of the right knee, the thigh and the leg. On the knee, there was complete deep ligament damage and joint exposition, together with a complete loss of anterior compartment.

On the thigh (distal third) and the leg, there was a soft‐tissue full‐thickness necrosis (skin and subcutaneous tissue) with muscular fascia integrity.

Again we collaborated with orthopaedics over the wound management. We started the surgical procedure with an early soft‐tissue debridement at day 3 after admission and the orthopaedics placed an external fixator in order to maintain the joint in a stable position.

Intraoperative bacterial swabs tested positive for meticillin‐resistant Staphyolococcus aureus (MRSA) and an antibiotic intravenous therapy was started on the base of the antibiogram.

As a result of contamination and unclear vitality of the exposed bones, immediate reconstruction was not considered acceptable.

After 5 days, the patient received skin grafts on both thigh and leg wounds.

For the knee joint, we decided on a conservative approach, also because the reaction of the patient's family to the proposal of amputation was negative.

We therefore started NPWTi on the exposed joint, with negative pressure at −125 mmHg for 4 hours followed by saline solution instillation for 20 seconds and soaking for 2 minutes. Change of dressing was performed every 5 days at the patient's bed under mild sedation.

After 35 days, NPWTi was stopped; the wound showed a valid granulation tissue and the intra‐articular swab result was negative. The orthopaedics performed a joint‐and‐bone debridement and definitive arthrodesis. External fixation was substituted with an Ilizarov circular external frame. During the same surgical operation, we covered the exposed bones with a medial gastrocnemious flap and a meshed skin graft.

Postoperative recovery was good with an excellent flap and graft take.

The Ilizarov fixator was removed 6 months later.

At a 4‐year follow‐up, we noticed stable soft‐tissue reconstruction with neither active nor passive range of motion in the knee joint. No secondary infections were detected. No further functional plastic surgery procedures were needed.

Case 3

Female, 55 years old, victim of necrotising soft‐tissue infection (NSTI) on left lower limb (Figure 3).

Figure 3.

A 55‐year‐old female with severe necrotizing fasciitis. (A) Soft‐tissue necrosis in the distal third of the leg with tendons and ankle exposition; the wound also extended to the dorsum of the feet. (B) Surgical debridement during negative pressure therapy with instillation. (C) Five‐year follow‐up after wound closure with meshed skin graft (medial view). (D) Five‐year follow‐up after wound closure with meshed skin graft (lateral view).

The patient came into our observation 20 days after admission to another regional hospital where she was treated for septic shock and acute kidney failure in NSTI.

Regarding soft tissue, there was loss of substance on the medial part of the foot, leg and popliteal fossae, with exposition of tendons, ligaments, fascia and lateral heel joint.

The patient was considered at high risk for amputation, also because her intra‐articular heel bacterial swab test showed positive results for MRSA and Escherichia coli; an antibiotic intravenous therapy was started on the basis of the antibiogram.

Together with the orthopaedics, we decided to postpone an immediate reconstruction because of the infection and the complexity of the wound, which had tissues of uncertain vitality. We decided on a conservative approach, and the orthopaedics inserted a Hoffman external fixator (Stryker Trauma AG, Selzach, Switzerland) while we positioned, after surgical debridement, NPWTi with negative pressure at −125 mmHg for 4 hours followed by saline solution instillation for 20 seconds and soaking for 2 minutes. Change of dressing was performed every 5 days at the patient' s bed under sedation.

After 20 days, NPWTi was removed; meanwhile, the intra‐articular swab became negative and the wound bed was ready to be covered.

We harvested an abductor digiti minimi muscle flap to close and fill the lateral malleolar joint; on it, and on all debrided tissue, a meshed skin graft was positioned. In the postoperative period a good flap and graft take was noticed.

The orthopaedics removed the Hoffman fixator 20 days later.

A 5‐year follow‐up showed a valid ankle joint excursion with a stable reconstruction. Even though the aesthetic outcome was not excellent, the patient satisfaction was high. Besides, the patient did not show any sign of secondary infection and no further cosmetic or reconstructive surgery was required.

Conclusion

In recent years, NPWT has represented a revolution in the field of modern wound treatment. In fact, NPWT is a recognised and powerful tool in the wound care setting. Treatment of chronic and acute wounds of traumatic, surgical or other origin has had great success with the application of this therapy 17, 18, 19, 20.

With this positive experience, new applications of negative pressure have been introduced in the market, ranging from silver sponge to gauze 21 to surgical incision management 22 to fluid instillation (NPWTi).

In particular, the major goals of NPWTi are to clean wounds, clear infection and enhance granulation tissue formation for primary closure or flap/graft coverage, thereby facilitating limb and implant salvage and early hospital discharge, and reducing the requirement of complex reconstructive procedures.

With these preconditions, NPWTi has become an important adjunctive tool in the management of complex wounds. Generally, instillation therapy is indicated for acute, traumatic, dehisced and chronic wounds, and ulcers (pressure, diabetic and venous), that would benefit from vacuum‐assisted drainage and a controlled delivery of topical wound treatment solutions and suspensions over the wound bed.

More specifically, NPWTi is used in wounds with high levels of exudate and slough presence , as well as acute traumatic wounds or wounds acutely debrided as a result of infected soft tissue 23. The combined therapy has also been reported 24 to be successful in cases of large areas of post‐debrided exposed bone, prosthesis salvage and joint exposition, and in cases of critical bacterial colonisation levels, as an alternative to antibiotic‐impregnated beads, when appropriate.

Our cases confirmed that NPWTi could be suggested as a local wound therapy for salvage limb strategy. In the acute phase of treatment with instillation of saline solution, we have had a rapid growth of granulation tissue, along with swab negativisation.

Experts are still debating about the best approach to use, but the literature review did not show a gold standard 24.

NPWT with normal saline instillation has been reported to potentiate granulation tissue formation at a higher rate in an acute porcine wound model 25.

At the same time, we did not find any scientific reports on a long‐term follow‐up after NPWTi use. Follow‐up controls are essential to check reconstruction quality together with bacteria control.

In fact even in our past experience 26, we have seen that a good initial reconstruction could lead to subsequent episodes of cutaneous ulcerations, resulting from the weight bearing on the damaged bone structure or from secondary osteomyelitis together with the impossibility of providing adequate soft‐tissue coverage. These local conditions could become a serious handicap for the patient and, after further orthopaedic assessment, could lead to secondary amputation.

In our few cases, all with very challenging wounds, we had stable reconstructions at an average follow‐up time of 5 years, with neither secondary ulcerations nor requests for other surgical procedures.

NPWTi has been demonstrated to be useful in the management of these complex wounds, when coupled with an appropriate antibiotic strategy and the correct surgical approach for joint exposition; this clinical experience permitted us to create guidelines in our hospital, focused on the use of NPWTi as a limb salvage procedure (Table 1).

Table 1.

Negative pressure therapy in limb salvage procedures

When	In complex limb wounds at high risk for amputation, as soon as possible after acute surgical debridment.
Why	To remove exudate, to protect open joints and to create healthy granulation tissue.
Which	Negative pressure with instillation that combines vacuum‐assisted drainage with a controlled delivery of topical suspensions over the wound bed.
How long	Till valid granulation tissue is generated for definitive coverage (mostly flap) and/or swab negativisation (not mandatory).

It is interesting to note that in all our patients, we observed how local swabs became negative during NPWTi treatment. The combination of lavage and negative pressure may, therefore, have increased the benefit of dissolving biofilm, inhibiting bacterial growth and replication.

Despite the fact that our reconstruction clearly failed in improving cosmetic appearance, the patients were fully satisfied about the plastic reconstruction, in the light of the consciousness regarding the conservation of the extremities.

In these complex wounds of the extremities, collaboration with orthopaedics is fundamental for determining the correct therapeutic strategy – first of all, to evaluate bone vitality and the possibility of immediate coverage with graft or flap, and then, after the decision to adopt a conservative approach with NPWT, to position external fixator wires in order to leave enough space for our vacuum‐sealed dressing tool.

In conclusion, though our experience is based on only a few cases, NPWTi has shown how it could be considered useful as a conservative approach in the treatment of acute complex wounds of the extremities. Long‐term follow‐up experience is mandatory to evaluate reconstruction quality on the vital and bacteria‐free wound bed created by NPTWi in patients at high risk for amputation.