The Use of Porcine Dermal Collagen Implant in an Extremely Difficult Case of Incisional Hernia Repair

It is not rare, that in patients undergoing multiple laparotomies there is a tissue loss with accompanying surgical site infection that enables abdominal wall closure with the use of the standard techniques. There are no level 1 statements imposing specific procedure in such difficult situations. However, it is generally recognized that synthetic meshes should not be implanted in the contaminated field.


Case Report
An obese male patient (BMI=34.6),aged 67, was admitted to the Department of General Surgery with the suspicion of the ileum obstruction, caused by incarceration of the small intestine in the incisional hernia post vertical banded gastroplasty surgery that he had undergone years before that was followed by surgical site infection (S. aureus).Three months before admission he had undergone open cholecystectomy that was also complicated by surgical site infection.
The patient was operated on due to obstruction; the operation was connected with hernioplasty with the use of 30 × 30 cm polypropylene mesh, using sublay technique.
After three days patient required another procedure, because of the recurrent obstruction.During the procedure the polypropylene mesh had been cut in order to explore the abdominal cavity and during the abdominal closure it was sutured.Six days after the second operation, eventration was stated.Exploration of the wound revealed that the fascia was infiltrated, brittle and tearing.Negative pressure wound therapy (NPWT) was applied because of the accompanying surgical site infection.The wound was not closed after that procedure.During the next dressing exchange, the contamination of the mesh had been stated and the decision of mesh removal was made.
NPWT was maintained with good results, and after four weeks, as soon as the wound was sterile and clean, confirmed by the microbiological result.The decision to implant the biological material was made.20 × 40 cm Permacol TM was implanted on the musclefascia layer, using sublay technique (Figure 1).Two drains above the fascia were left.Moreover, sutures preventing from eventration were placed as well.Three days post Permacol TM implantation a massive leakage from the wound was noticed connected with the necrosis of the wound brims.The removal of the sutures was necessary.After wound exploration, it turned out that dissolved Permacol TM had caused the leakage.The biological mesh remained intact only on the brims (Figure 2).According to the histopathological examination of the removed Permacol TM , there were features of granulation, acute inflammation and foci of necrosis.Patient required open wound healing, connected with NPWT, nevertheless there were no microbiological cultures.NPWT was maintained for another month, during which another infection appeared.The culture of the wound revealed S. epidermidis that was treated by intravenous vancomycin therapy.The next step was the cleaning with the use of the water knife.The part of the wound was sutured, on the bottom part of the wound NPWT was implied.After another week the remaining part of the wound was sutured.
The patient was discharged to the outpatient clinic after 100 days.Dressing change three times a week was necessary, due to the sterile serum leakage from the wound (Figure 3).Because of the lack of progression of the wound closure, new sutures were added 2 times.After one month  of unsuccessful wound closure-brims of the wound were anergic, the decision about surgical cleaning of the wound and resuturing connected with Permacol TM implantation was made (Figure 4).Wound swab was sterile; patient had lost 20 kg (BMI=28.75)since the first surgery.During the procedure of the second Permacol TM implantation, the brims of the wound were refreshed; the tissues that have been included in the inflammatory infiltration were removed.The fascia was identified (Figure 5) and slightly separated from the thickened peritoneum (Figure 6).Permacol TM after previous preparation was implanted with sublay technique (Figure 7) and the fascia was closed above it.Fascia closure was possible probably due to the patient's weight reduction.Moreover, it might have had an influence on the final results of treatment (Figures 8 and 9).One week after the second repair surgery magnetic resonance imaging was done in order to visualise the presence of the biological material (Figures 10 and 11).There was a small amount of fluid along the whole implanted material.After the 4 months of treatment patient was successfully discharged with completely healed wound and without abdominal hernia.

Discussion
There are different approaches toward dealing with cases connected with difficult wound healing and complex abdominal wall defect.Reconstruction of a large defect of fascia in patients suffering from other diseases, e.g.obesity, cardiovascular problems or in patients who are taking immunosuppressive drugs is a challenging problem for the majority of surgeons.The primary suture repair is associated with the lowest risk of infection, but firstly, recurrence rate of hernia in this way of repair exceeds up to 60% [1][2][3][4][5] and secondly, huge fascia defect often makes is technically impossible to close the wound without excessive tension.
Permacol TM is a laminar mesh derived from porcine dermal collagen, crosslinked with hexamethylene diisocyanate and consists mostly of type I collagen, 5% type III collagen and elastin.There is a conviction that Permacol TM may be used in the contaminated field, though there is no level 1 evidence [3] confirmation of that thesis.For that reason, many authors support that statement with the stipulation that it should be reserved for the multicomplicated cases only.
It is commonly believed that biological materials have lower affinity for bacterial colonization [4], which is contradictory to the examination performed by Perez-Kohler et al. who claims that the conventional nonabsorbable polymer materials are better option for use in contaminated surgical fields [1].In our case, Permacol TM was implanted in the sterile field.The reason of the first failure of Permacol TM implantation in our patient was the lysis of the biomaterial for the unknown reason and it seems it is not connected with microbiological infection.As Novitzky [2] noticed in his research, implantation of the biological material induces cell infiltration, which was confirmed in our histopathology examination.
Because of the former polypropylene mesh infection, we decided not to implant the polypropylene mesh again.Moreover, biologic implants are believed to have less potential for bowel adherence [6] that is extremely important while placing the graft with the use of intraperitoneal sublay technique with bridging.
Another putative advantage of Permacol TM is its flexibility that does not prevent from the neovascularization.One of the probable reasons of the mesh lysis in our case might have been the material disintegration or poor mash incorporation.Those complications were described by Harth [7,8].
There are cases describing the successful usage of Permacol TM in the contaminated field [7].According to our centre experience, we are in agreement with that statement.
Relying on our centre experience, Permacol TM can also be safely used in the post transplantational patients who are put on immunosuppressive therapy.
There are no standard procedures for coping with such difficult cases, but without any doubts the commonly recognized risk factors as accompanying infection, diabetes mellitus or obesity have a negative impact on the wound healing and abdominal wall closure.Furthermore, it is extremely important to treat each patient individually.

Conclusion
Our goal was to present the case of coping with extremely difficult wound healing case and the very rare entity of Permacol TM dissolving.
One may notice, that from time to time the simplest option is the best option (in that case closure of the subcutaneous layer and the skin, with the adjournment of the abdominal plasty).Planning tworound treatment turned out to be the best option in that specific case, nevertheless it did not preclude the reuse of Permacol TM with good effect.
The results of use of biological material are not ideal, however biological materials may be useful in the selected group of patients.Further examination regarding the use of biological materials should be performed.

Figure 2 :
Figure 2: The biological mesh remained intact only on the brims.

Figure 3 :
Figure 3: Dressing change three times a week was necessary, due to the sterile serum leakage from the wound.

Figure 4 :
Figure 4: Surgical cleaning of the wound and resuturing connected with Perma-colTM implantation.

Figure 7 :
Figure 7: Permacol TM after previous preparation was implanted with sublay technique.

Figure 8 :
Figure 8: Fascia was closed above it.Fascia closure was possible probably due to the patient's weight reduction.

Figure 9 :
Figure 9: It might have had an influence on the final results of treatment.

Figure 10 :
Figure 10: One week after the second repair surgery magnetic resonance imaging was done in order to visualise the presence of the biological material.

Figure 11 :
Figure 11: There was a small amount of fluid along the whole implanted material.