Biomechanical assessment of the preperitoneal hernial repair by a bipedicled external oblique aponeurotic flap: mobility of the floor of the inguinal canal

Abstract

Introduction Development of indirect inguinal hernias through the inguinal canal is usually prevented by the shutter and the sphincteric mechanisms, which are known to be destroyed by almost all anterior herniorrhaphies. Objective A new preperitoneal repair, which uses a bipedicled external oblique oponeurotic flap, has been recently introduced and was suggested to change the mechanics of this area. In this hernia repaires, the biomechanics of the inguinal region were assessed in healthy individuals and in patients with hernia after new repair and after other conventional anterior hernial repairs. Methods The study included 20 patients with inguinal hernias and 5 non-hernia control cases (group A). Ten of the hernia cases were repaired by the new preperitoneal repair (group B) wheareas the other 10 were repaired by convemtional anterior repair (modified Bassini) (group C). The 5 control cases were selected from patients without hernia, who were scheduled for inguinal surgery for excision of symptomatic varicoceles. During surgery in all cases, two ligaclips were inserted into the ileopubic tract. After sound healing, all cases were radiographed to detect any change in the position of the ligaclips, on contraction of the external oblique muscle. Any displacement of the inserted ligaclips was considered in this study as a sort of mobility at the floor of the inguinal canal, induced by the contracted muscle. Results The study showed that contraction of the external oblique muscle induced, in all cases, a degree of an upward displacement of the floor of the inguinal canal, which could be called a reversed shutter movement. The magnitude of this reversed shutter mobility was nearly identical in normal controls and in cases that underwent conventional anterior hernial repairs. Conclusion The new preperitoneal repair, with the bipedicled external oblique oponeurotic flap, was found to augment this reversed shutter movement significantly. The possible explanation and the forces that possibly induced this reversed shutter mechanism are herein presented and discussed.

Keywords

• biomechanical assessment
• inguinal canal
• reversed shutter mechanism