The anatomy of the anterior abdominal wall has consistently been of interest to anatomists over decades. It played a significant role in surgery. In addition, the abdominal wall was considered an important way in opening the peritoneum where it is involved in hernia sac formation. Therefore, the anterior abdominal wall is the object of different surgical investigations regarding wound healing and wound closure .
One of the commonest problems faced by the paediatric surgeons is the umbilical hernia. The recurrence rate of umbilical hernia was reported to be around 10–15% . The traditional repair of the umbilical hernia included transverse closure of the fascial defect in the linea alba . This technique is being used for both types of umbilical hernia without taking into consideration the structural difference between the two types. Most of the literature studies are discussing the difference between interrupted and continuous closure or repair with and without a mesh .
In El Den et al.’s study, there was no difference between continuous and interrupted closure of umbilical defect . We could not spot any study in the literature about the histological difference of the umbilical defect and the implication on repair.
Conze et al. in 2005 attributed the high recurrence rate of incisional hernia (40%) to the direction of the suture line in relation to the transverse collagen fibres in the linea alba. This assumption opened the way to think about the role of the transverse collagen fibres in the linea alba in wound healing .
Axer and his colleagues in 2001 demonstrated that the lamina fibrae transversae (the transverse fibres in the linea alba) may be of significance in the choice of direction of laparotomy incision. They added that transverse laparotomy incisions are more resistant to rupture than longitudinal incisions. In fact, in transverse laparotomy, the transverse fibres in linea alba and rectus sheaths are not cut and can serve their function, while in longitudinal incisions, the sutures are not fixed in between the cut transverse fibres .
In this study, the histological structure of the umbilical ring in both types of umbilical hernia was studied to detect the difference in the structure between the two types and to modify the technique of surgical repair according to the arrangement of the collagen fibres to give more strength to the repair by repairing mainly the transverse collagen fibres in the linea alba. The patients in our study underwent surgical repair of their umbilical hernia by the traditional method (the transverse closure of the fascial defect in both types of the hernia), and before closure, a biopsy from the upper, lower, right and left corners of the umbilical ring was taken. The biopsies were preserved in 10% formalin and paraffin sections were done after drying and cleaning of the specimens. The specimens were stained with haematoxylin and eosin and examined under the light microscope.
Collagen was found to be the predominant protein in the abdominal fascial layers and accounts for 80% of the structural tissue. Two types of collagen fibres were found in the architecture of linea alba, transverse fibres which are responsible for counteracting intrabdominal pressure and oblique fibres which are involved mainly in the movement. Reduction in wound transverse collagen level decreases the wound tensile strength and increases the risk of mechanical wound failure and may lead to wound dehiscence .
We found that the arrangement of the collagen fibres in the four corners of the ring of umbilical hernia differed significantly in both types of the hernia. In the direct type, the transverse collagen fibres were significantly more predominant in the upper and the lower borders of the ring. Therefore, closure will be more stable if it is performed in a transverse manner (the upper and lower borders come in apposition). In the indirect type, the transverse collagen fibres were significantly more predominant in the right and left borders of the ring. So, the closure will be more stable if it is performed in a longitudinal manner (the right and left borders come in apposition).
We have no sufficient data to determine if this structural difference has in practice surgical implication or not, but this can be very helpful to be applied in recurrent cases to decrease the incidence of dehiscence. Further studies using electron microscopy to detect the amount of collagen in the four corners of the umbilical ring might be very helpful to confirm or reject our hypothesis. Considering other factors that might lead to recurrence like comorbidities, type of sutures and size of umbilical hernia should be considered before applying any changes to the standard way of umbilical hernia closure.
There are some other factors that may affect healing and increases the recurrence rate like age and sex of the patients, but previous studies in the literature showed no significant effect on recurrence rate [13, 14].