Complex abdominal hernia repair represents a significant challenge for surgeons. Complex hernia could be differently defined. The complexity of hernias could derive from contamination/infection, tissue loss, dimensions, anatomic position and clinical or pharmacological data.
For sure the introduction of tension-free techniques, thanks to the use of prosthetic materials, has greatly facilitated the duty. On one hand prosthetic techniques have been demonstrated to reduce the recurrence rate, on the other hand they introduced a series of new variables to take into consideration when repairing abdominal wall defects: actually prosthetic infection, dislocation, chronic pain, shrinkage, adhesions formation, fistula formation and skin erosion complicate the decision process in abdominal wall repair surgery. With the introduction of resorbable materials some of these factors have been eliminated with an increased recurrence rate as a counterpart. BP has completely changed the way to face the abdominal hernia surgery. They introduced the tissue engineering in field of the surgical practice
. The implant of biologic materials elicits a cascade of events leading to new healthy tissue deposition and prosthesis remodeling. It also allows to blood, growth and pro-/anti-inflammatory factors and drugs to reach the surgical field during the first phases of healing process. This for sure enhances the effect against potential or definite contamination/infection. Moreover the adhesiogenic power of BP is absolutely lower than the one of the other synthetic materials
[13, 14]. On the contrary there are a few doubts about the intra-peritoneal use of BP from the biomechanical point of view. It has been demonstrated that the best integration is reached if they are placed pre-peritoneally with a greater incorporation strength, less adhesion area and lower adhesion scores compared with intra-peritoneal placement
. Given that the long-term persistence of the prosthesis is crucial, some authors stated that the BP durability has a direct impact on the recurrence rate
. However durability depends on the implant intrinsic properties and also on the environment into which the BP are placed
. It has been demonstrated in animal models as the tensile strength is different between cross-linked and non-cross-linked meshes during the first months after the implant. However it reaches similar values after 12 months with the two kind of implants
. Moreover the strength of the repair sites doesn’t change over time. This might indicate that new tissue is deposited in the repair site as the scaffold is degraded, preventing the site from weakening over time
. Another factor that should be kept into account in choosing which kind of BP to use is the demonstration that non-cross-linked material exhibits more favourable remodeling characteristics
. This has a great importance when BP are used as bridging or alternatively as reinforcement. In fact discordant data have been published about the use of BP to bridge wide defects
. Few different non-randomized studies have been published reporting recurrence rate ranging between 100% and 0% if the prosthesis are placed respectively either as a bridge or not
[16–19]. Even if high-quality comparative data about BP exist in animal models, only clinical reports of a restricted number of cases are reported for humans. Moreover only the recurrence rate is registered as outcome in almost all studies. Other data regarding the use of BP as wound classification, contamination risk/grade, associated therapy or comorbidity are seldom reported. These data are needed to completely assess the usefulness, the efficacy and the versatility of BP. All reported data derived by retrospective uncontrolled series of limited number of patients. The methodology is seldom reported and/or poorly described. Moreover the time to recurrence is rarely evaluated
. One last observation is that the different studies reported data about non-homogeneous cohorts of patients. Different surgical techniques, different surgeons’ skill and expertise in using BP and different hernia sites are often mixed together. These inconsistencies are probably due to the poorness of cases for each single centre. No definitive evidence based conclusions could be obtained from the literature. The majority of surgeons stated that they use BP in “difficult” situations, especially those with contaminated or infected field
[16, 20, 21].
The present decisional model suggests, at the best of our knowledge, the way to apply scientific knowledge to the clinical practice in order to choose which type of BP use in abdominal wall defects repair. This should always be a dynamic process mediated by the surgeon decisional capability. We resumed the principal variables to keep in mind in deciding the kind of BP to use. Infection has been divided into three possible grades:
The same three steps division has been adopted for the tissue loss:
By combining together these variables (multiplication) we obtained a score which determine the necessity to use either a cross-linked or a non-cross-linked BP (Figures
Operating field has been divided into three groups. In a previous grading system by the Ventral Hernia Working Group (VEWG) the four grade of risk for surgical site occurrences have been differentiated by considering also the comorbidity of the patients
. Clinical conditions are to be kept in mind in evaluating the use of prosthesis but in the present decisional model the principal aim is to help the surgeon to decide whether use cross-linked or non-cross-linked BP.
Undefined situations still exist. Cases with a score between 2 and 6 represent all that patients with a big tissue loss and a potential/low grade infection or vice-versa cases with an high grade infection and a low or null tissue loss. These cases need a cautious evaluation by the surgeon to establish if the priority has to be given to the tissue loss or to the grade of infection. The VEWG score could help in deciding. Infected fields with no residual loss of tissue don’t represent an absolute indication for BP use. On the contrary a small tissue loss with concomitant low/null infection but high comorbidity could suggest using a non-cross-linked BP. The higher resistance to protease enzyme action and to mechanical stress of cross-linked BP suggest using them in situation of high infection and/or big defects. As counterpart, however even in presence of a high grade infection with a low grade tissue loss could be suggested to place a non-cross-linked BP.