Pathological Tissue Changes and Hernia Formation
Classically, inguinal hernias are considered the result of a multifactorial process linking predisposing anatomical and dynamic factors: intra-abdominal pressure acting on a weak area, the myopectineal orifice, which is sealed by the transversalis fascia.
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Introduction Classically, inguinal hernias are considered the result of a multifactorial process linking predisposing anatomical and dynamic factors: intra-abdominal pressure acting on a weak area, the myopectineal orifice, which is sealed by the transversalis fascia. All groin hernias are therefore characterized by the displacement of this fascia by a peritoneal sac. There are individual anatomical variations that aggravate the fragility of the inguinal region, enlarging the weak area and rendering less effective the physiological protective mechanisms of the inguinal region. l To these are added histobiochemical factors, which are unquestionably the least known at present, but very likely playa key role in the genesis of inguinal hernias. In the light of the work of Peacock and Madden2 and Wagh, Read, and Cannon,3-6 it appeared that hernia formation was actually based on much more fundamental metabolic collagen anomalies. Hence, inguinal hernia could be considered a local manifestation of systemic collagen pathology. This aspect has, however, been studied very little up to now. This is why we undertook a detailed study of the transversalis fascia and the sheath of the rectus abdominis muscle in control groups and in patients with inguinal hernias. We first analyzed the macroscopic biomechanical properties of these structures, then proceeded to the microscopic level in an attempt to clarify them by means of their histologic characteristics.
Biomechanical Characteristics of the Transversalis Fascia and the Anterior Rectus Sheath We have at our disposal very little information concerning the mechanical properties of the transversalis fascia. Minns and Tinckler7 have studied the mechanical characteristics of the transversalis fascia of inguinal hernia patients. The ultimate tensile strength of these tissues was lower than that of controls. All the patients in our study underwent bilateral inguinal hernia repairs, whether the condition was itself bilateral or whether it was decided, with the patient's consent, to treat the unaffected side preventively. The technique used was a midline suprapubic approach with placement of a prosthesis on each side in the R. Bendavid et al. (eds.), Abdominal Wall Hernias © Springer Science+Business Media New York 2001
preperitoneal space. Once the preperitoneal dissection was accomplished, good exposure of the posterior wall of the inguinal canal was obtained. Biopsies of constant surface area were taken from the transversalis fascia, on the left and right sides, as well as from the anterior rectus sheath. Analogous samples were taken from a control group made up of autopsy subjects within 24 hours of death and of organ donors. The study included 63 patients (89% men) with 88 groin hernias. Mean age of patients was 57.7 years. The hernias were indexed according to the classification of Nyhus. s Eligible for the study were 38 fascias from nonherniated groins, 32 from indirect hernias (type II), 40 from direct hernias (type IlIa). The mean age of the 30 control subjects (63% men) was 5
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