Wound healing is a continuous and complex procedure which involves cell proliferation, cell migration and eventually the restoration and closure of the wound. Still, even though in our time, there is a plethora of treatment options for wound healing such as systemic and local antiseptic administration, different dressing types even hyperbarbaric oxygen; the treatment of chronic wounds is still an enigma for most surgeons .
However by 1993 a new solution has been suggested by Fleischmann  who introduced the idea that chronic wounds could be managed via negative pressure. This idea was eventually supported via experimental data from Argent [3, 4] in 1997 who published a study, in which he applied negative pressure coverings on injuries of the torso and the extremities. The aforementioned system is known as vacuum-assisted closure system (VAC) (San Antonio, Texas, USA).
Vacuum assisted closure (VAC) therapy is a trustworthy technique that is proven to support and to increase the blood perfusion of the dermal and sub-dermal tissue. It also, enhances the formation of granulation tissue while on the other hand it prevents the accumulation of interstitial fluid, exuded bacteria load and debrides to the wound [5, 6].
Parrett et. al.  published a study in 2006 in which he reports the use of the VAC system in order to reconstruct the soft tissue of injuries in the lower extremities. In his study Parrett mentioned an increased usage of the VAC system while the rates of infection, malnutrition/non-union and amputation remained the same and the need for re-operation declined.
However, the application of a VAC system over a free flap has not yet been widely reported in the literature as potential pressure over the flap can compromise its perfusion. Herein, we report a case of a crash injury of the foot, which was initially dealt with a free flap and split thickness skin grafts (STSG). The free flap supported with the VAC system after an infection which resulted into total graft loss. This case repost is presented according the consensus-based surgical case report guidelines .
47 year old female previously fit and well and with no medical co-morbitities was brought to the St. Lukas Hospital, by ambulance after a car accident. The patient had no past medical history, no previous surgical interventions and was not on any medication. She was also not allergic to any medication, she was not drinking and was not a smoker.
Clinical Findings, Diagnosis assessment and Therapeutic intervention
The 47 year old woman had sustained a crush injury of the left foot due to the car accident (Figure 1). After several surgical debridements and control of the local infection with antibiotics(co-amoxiclav), VAC therapy was applied for 2 weeks. The tissue loss was proximally 2/3 of the sole and the dorsal of the foot (Figure 2). Dr. Sapountzis (plastic surgeon), Dr. Goulios(orthopaedic surgeon), Dr. Rallis(orthopaedic surgeon) and Dr. Karamitros (surgical trainee) used a free mascolocutaneous lattisimus dorsi (LD) flap, which was transferred to cover the extensive deficits of the area. End-to-end arterial anastomosis was completed with the posterior tibial artery and concomitant vein as recipient vessels. STSGs were applied to cover the lattisimus dorsi (LD) free flap (Figure 3). The patient was then moved to the High Dependency Unit (HDU) and was closely monitored.
Follow-up and outcome
On the first post-operative day, there were noted significant signs of venous congestion on the flap. Therefore, the patients was taken back to the operating room and the pedicle was explored. In order to treat the venous congestion, a 14 cm of saphenous vein was harvested from the contralateral leg and was used as a graft between the thoracodorsal vein and the great saphenous vein (Figure 4). However, on the 4th day, we noticed, during a dressing change, that the leg demonstrated signs of local infection, which resulted in total graph loss (Figure 5).
Conservative methods were followed until the 8th post-operative day, when we decided to use VAC therapy as a saving procedure. Vacuum dressings were applied over the flap and 50 mmHg of low pressure settings were selected (Figure 6). VAC dressings were changed every 36 hours and the flap was thoroughly monitored. Close monitoring of the flap ensured that there was not any signs of flap congestion, meanwhile the perfusion of the LD flap remained adequate.
One week later, there was healthy granulation tissue formed over the muscle (Figure 7) and STSG was reapplied, using the VAC as a splint over the graft to prevent shear (Figure 8). Four days later, the wound was rechecked and more than 90% of the skin graft was successfully accepted in the deficit area.
The flap had a 100% survival rate and there was no evidence of necrosis, while there was no need for revision surgeries. In the 3 months and 6 months follow-up the patient is able to walk and there was no episodes of infection or ulcer formation (Figure 9).
One of the most serious and crucial complications related to free tissue transfers is venous occlusion, which many times can be proven catastrophic. Venous thrombosis usually occurs first, leading to microcirculatory failure, which then evolves to arterial thrombosis and finally total graph loss .
Multiple factors can result to a total venous blockage such as haematoma formation, pedicle twisting, even thrombosis of the anastomosis . As mentioned before, the venous anastomosis is the first region to form a clot, which then leads to the disruption of the microcirculation of the flap, leading to total graph loss.
Venous congestion can be subdivided to total or partial blockage. The initial treatment of partial venous congestion includes medicinal or chemical leaching, however total blockage requires thromboembolectomy or venous re-anastomosis of the flap . In our case, the initial problem was the venous congestion of the LD flap. Firstly we applied conventional methods. Afterwards we inspected the vessels of the flap and venous anastomosis was reapplied by interposition of a vein graft, using the great saphenous vein of the contralateral leg, however the problem was not solved. Still, even though the artery was able to perfuse blood to the flap, the venous system was inadequate. As a result, the flap started to show signs of infection and necrosis.
We presumed that venous congestion had deteriorated, most likely due to the increased interstitial pressure. As a result, the application of VAC therapy in low negative pressure settings over the flap would remove the additional interstitial fluid. VAC therapy is described to decrease interstitial pressure, leading to the restoration of capillary perfusion and the achievement of blood flow to the flap. Even though, the physiological mechanisms involved need to be further examined, the practicality of the VAC therapy effects seem to explain the results. The period needed to achieve those results from VAC therapy are not quite obvious yet, however 6–7 days or a week seems like the ideal duration. During this time, neovascularisation of the flap would have occurred and venous outflow would be sufficient.
There were scarce literature findings that document the use of VAC therapy over a free flap, one was the use of VAC therapy over a superficial inferior-epigastric flap to third-degree burns on hand and fingers  and the other was over an anterolateral free flap used to cover deficits after wide excision of palmar contracture .
One thing that should always be considered is that the application of VAC therapy can add pressure on the flap, thus compressing it and creating an obstacle in its arterial flow. This should always be considered before initiating VAC therapy over a free tissue transfer. This is after all, the reason why most surgeons are reluctant to use VAC therapy on a free flap.
Conclusion – “Take away” lessons
In the end, it seems that VAC therapy may be an extra treatment option in cases where interstitial pressure rises over capillary pressure, leading to flap infection and flap loss. More studies need to be performed, in order to safeguard the efficacy and applicability of this tenchique.
The patient was fully aware of the difficulty of the reconstruction. She was always informed about the interventions that we were implementing. However, most importantly, she was very compliant and followed our instructions closely which led to the best possible result.
The patient was informed and asked before the implementation of this case report and is fully aware and compliant with the scope of this study.