THE INFLUENCE OF THE NUMBER OF ENDOCLIPS AND OF MESH INCORPORATION ONTHE STRENGTH OF AN EXPERIMENTAL HERNIA PATCH REPAIR

The strength conferred to a mesh by fixing it with laparoscopic staple s and the effects of tissue incorporation have never been quantified. Eighteen dogs were divided into three groups sacrificed at 2 days (5 d ogs), 2 weeks (6 dogs), and 2 months (7 dogs). One 3.5- by 5-cm piece of abdominal wall was removed from each side through a median laparoto my, leaving the skin intact. A polypropylene mesh (5 by 7 cm) was fixe d over one defect with four Endopath EMS staples (Ethicon Endo-surgery ) and over the other with 16 EMS staples. At sacrifice, bursting stren gth (BS) was measured with an Instron tester and specimens were studie d histologically. One-way analysis of variance and the Newmann-Keuls m ultiple-comparison test were used. BS tests showed that for each perio d studied, the strength of the repair performed with 16 staples was si gnificantly higher than that obtained when four staples were applied. They also showed that tensile strength increased significantly in both groups as time elapsed. Light microscopy supported the conclusion tha t the initial strength of the repair was related to the number of clip s and was significantly increased by cellular infiltration at 2 weeks and significantly more by collagen deposition at 2 months. At 2 months , BS was significantly higher in the 16-staples group, suggesting that initial fixation still plays a significant role.