Mechanical characterization of the equine linea alba and finite element modeling of suture patterns effects on its closure.

Postoperative incisional complications are common in horses following abdominal surgery, which typically involves an incision through the abdominal wall along the linea alba. The linea alba is a fibrous band running in the craniocaudal direction along the ventral abdomen. This incision is closed with sutures, where the choice of suture pattern and surgical technique has shown to influence the rate of complications. Therefore, this study investigated how different suture patterns and variations influence the stresses in the tissue by combining experimental and computational biomechanics. The mechanical properties of the equine linea alba were first characterized using uniaxial tensile tests. The samples were loaded in either the longitudinal, craniocaudal, or the transversal, laterolateral, direction. Based on the resulting stress-strain data, the Gasser-Ogden-Holzapfel material model was calibrated. This material model was then applied to develop a finite element model of the sutured linea alba, using an interrupted suture pattern. By changing the bite size, the distance from the incision to the suture entry point in the tissue, and the step size, the distance between stitches, their effect on the maximum principal stresses was analyzed. Additionally, a continuous suture pattern was modeled for comparison with the interrupted pattern. The tensile tests revealed stiffer behavior of the linea alba in the longitudinal direction compared to the transversal direction. An increase in bite and step size led to a rise in the maximum principal stresses, with bite size having the largest effect. Switching from an interrupted to a continuous pattern only slightly increased stresses.