Collagen metabolism and recurrent hiatal hernia: cause and effect?

Hiatus hernia (HH) is a condition characterized by herniation of the intra-abdominal organs into the thorax. Of the several types that have been identified, the most common is type I (sliding) HH. Congenital predisposition and acquired factors, for example trauma and iatrogeny, have been identified as causative factors. There is a strong association between gastroesophageal reflux disease and HH—the prevalence of reflux in HH may reach 94%. Many methods have been used to treat reflux disease and HH, among which are laparoscopic techniques, which gained popularity as a safe method of treatment. Primary crural repair without mesh application was found to have a recurrence rate of up to 42%. This led to the introduction of mesh in HH repair, which was associated with a significant decrease in recurrence rate. Collagen and its relation to hernia have been investigated for several decades. Collagen has mechanical properties sufficient to enable it to support healed scars and other tissues. Nineteen distinct types of collagen have been recognized, the most common of which are types I and III. Type III collagen is the major constituent of early granulation tissue whereas type I predominates as healing proceeds. Collagen fibers are imbedded in extracellular matrix (ECM), which is in continuous process of synthesis and degradation under the action of matrix metalloproteinases. Many authors have studied the role of collagen in ventral hernia and have even defined hernia as a disease of the ECM. The relationship between collagen and HH, and its recurrence, is not fully understood and needs further investigation.