LAPAROSCOPIC VENTRAL HERNIA REPAIR BY LIGHTWEIGHT POLYPROPYLENE MESH. A PROSPECTIVE ITALIAN MULTICENTRIC RANDOMIZED STUDY COMPARING TWO FIXATION DEVICES: TITANIUM SPIRAL TACKS vs ABSORBABLE TACKS

BACKGROUND During the past 50 years, incisional and ventral hernia repair surgery has evolved from direct suture repair to the use of synthetic mesh in order to obtain a tension-free repair (1-3). Finally the tension-free concepts have been applied to laparoscopic surgery. Laparoscopic repair of ventra/incisional hernias has gained increasing popularity, since many studies and a recent meta-analysis and consensus conferences have reported encouraging results, in terms of wound infection, hospital stay and post-operative pain with recurrence rate comparable with open approach (1-7).

Patient selection (age, sex, comorbidities, obesity, hernia site and size, eventual recurrence and type of previous abdominal surgery), choice of the mesh (bio-materials, size and shape) and fixation methods (titanium tacks, absorbable tacks, fibrin glue) are considered crucial issues in preventing recurrence and complications as well as patients compliance and acceptance (4-5, 8-9). The choice of the mesh to implant is of paramount importance, in open as well as in laparoscopic approaches. During the last decade, many meshes and fixation devices have been proposed and tested as a tool to enhance primary and incisional/ventral hernias repair (10-11). Light-weight meshes have been proposed in order to reduce the mesh and/or mesh fixation related complications (12). Decreasing the density of non-absorbable material a reduced "foreign-body response" has been postulated, resulting in improved abdominal wall compliance, less mess shrinkage, thus allowing a better integration in host tissues (13-14).

The "lightweight approach" is also based on the results of studies concerning the abdominal wall biomechanics (15-16) suggesting the characteristics of the "ideal mesh" (elasticity, tensile strength and pressure resistance) similar to the normal abdominal wall. The ideal mesh, should be elastic enough to comply with the movements and elongation of the different areas of the abdominal wall, yet rigid enough to avoid the herniation of the mesh itself, and strong to resist in its position, without degradation, deformation (shrinkage) or creation of defects, life-long.

Among the great amount of meshes and materials utilized for laparoscopic repair, macropore lightweight polypropylene has been demonstrated to be more efficient than other materials (including heavy weight polypropylene) in terms of inflammatory response and mesh integration on host tissues (17-21). The other crucial issue inlaparoscopic repair is the choice of the mesh fixation method: the most commonly used include metal spiral tacks set in a double crown configuration (22-26). Absorbable tacks have been recently introduced (27) in order to improve biocompatibility, reduce the risk of endoperitoneal adhesions due to the presence of metallic tacks, and reduce mid- and long-term postoperative pain. The rationale of the use of absorbable tacks in laparoscopic incisional/ventral hernia repairusing lightweight macropore polypropylene meshes is in the biochemical and biomechanical mesh features, since these meshes become well integrated into the abdominal wall and do not need permanent fixation devices. To date, only two retrospective studies dealing with the clinical use of absorbable tacks with lightweight macropore polypropylene mesh have been published (28-29). The authors report similar results comparing absorbable vs non absorbable tacks in terms of intraoperative and early post-operative results (29). These studies have the pitfalls to be retrospective evaluation on a small series of patients, so the reported results still need to be validated by larger series and prospective study.

THE PRIMARY END POINTS of this prospective multicentric randomized study are: