Investigation of abdomen surface deformation due to life excitation: implications for implant selection and orientation in laparoscopic ventral hernia repair.

BACKGROUND Ventral hernia is a common medical problem. Statistically there are around 10% recurrences of the sickness. The authors' former investigation proved edges of the hernia orifice displacements to be one of the factors causing recurrence. Thus, experimental investigation of the abdomen surface deformation due to some normal activities of people is studied. METHODS Eight slim, healthy people were asked to extremely stretch their abdomens. Bending, stretching and expiration were considered. The deformations registration was made by two cameras located in front of the patient on both sides. Special calculation procedure was used in order to transform characteristic point displacements to strains of abdomen in different directions. FINDINGS The extreme strains, their localization and directions are identified. The study proves that the highest strains, bigger than 25% on average, appear in the upper part of the central vertical line of the abdomen and in lower sides in semi-vertical direction. The lowest strains, smaller than 7%, occur in a horizontal line situated low in the abdomen. For each patient similar zones of smaller or bigger strains are identified, however a wide discrepancy of the strain values obtained for different patients is stated. For example the strains in lower part in semi-vertical direction for one patient equals 9% and for another 134%! INTERPRETATION The acquired conclusions may be useful for surgeons in finding practical solutions to dilemmas concerning the choice of an implant (elastic or stiff) for a specific ventral hernia, its proper connection with fascia and orientation in the abdomen.