Addressing parastomal herniation through biomechanical simulation.

Purpose: Parastomal hernia remains a significant source of post-operative morbidity. Existing surgical solutions have shown limited success while not addressing the biomechanics underpinning parastomal herniation. The primary objective was to examine the influence of stoma aperture shape on abdominal wall stress and tissue destruction. The secondary objective compared mesh designs with respect to abdominal wall stress.

Methods: Finite element analysis of an abdominal wall model was used to simulate various stoma and mesh designs. The outcome measures were abdominal wall (mmHg) pressure required to initiate tissue tearing, stress distribution and median and peak abdominal wall stress (N/m).

Results: The simulation demonstrated that the cruciate stoma incision developed high stress concentration at the apices of the slit incisions. The circular stoma incision distributed stress uniformly. The circular stoma design was more resistant to tissue tearing. The Keyhole mesh design demonstrated the lowest median and peak stress at 17.32 and 28.01 N/m. This was a statically significant reduction in stress compared to the Sugar Baker and no mesh designs (p < 0.001).There were no significant differences between the Keyhole mesh design and loose mesh designs as long as the loose mesh design aperture did not exceed 1.5 times the stoma aperture diameter (p = 0.223).

Conclusions: This study has demonstrated that the shape of the fascia incision and mesh design have a significant impact on parastomal hernia formation. Novel designs can be used to optimise the stoma. The circular stoma and loose mesh designs are promising avenues for future research.