Effect of repetitive loading on the mechanical properties of biological scaffold materials.

BACKGROUND: Coughing, bending, and lifting raise the pressure inside the abdomen, repetitively increasing stresses on the abdominal wall and the associated scaffold. The purpose of this study was to evaluate the effect of repetitive loading on biological scaffolds. It was hypothesized that exposure to repetitive loading would result in decreased tensile strength and that crosslinked scaffolds would resist these effects more effectively than non-crosslinked scaffolds. STUDY
DESIGN: Nine materials were evaluated (porcine dermis: Permacol, CollaMend, Strattice, XenMatrix; human dermis: AlloMax, FlexHD; bovine pericardium: Veritas, PeriGuard; and porcine small intestine submucosa: Surgisis; in addition, Permacol, CollaMend, and PeriGuard are crosslinked). Ten specimens were hydrated and subjected to uniaxial tension to establish baseline properties. Thirty specimens were hydrated and subjected to 10, 100, or 1,000 loading cycles (n = 10 each).
RESULTS: Tensile strength remained unchanged for CollaMend, XenMatrix, Veritas, and Surgisis during all cycles (p > 0.05). However, Strattice and AlloMax exhibited reduced tensile strength, and Permacol, FlexHD, and PeriGuard exhibited a slight increase in tensile strength with increasing number of cycles. Crosslinked bovine pericardium (PeriGuard) displayed greater tensile strength than non-crosslinked bovine pericardium (Veritas) and crosslinked porcine dermis (Permacol) exhibited greater tensile strength than non-crosslinked porcine dermis (Strattice, XenMatrix) during all cycles (p < 0.0001).
CONCLUSIONS: Materials that rapidly lose strength after repetitive loading might not be appropriate in clinical scenarios involving elevated stresses, such as in patients with high body mass index or when replacing large areas of the abdominal wall without tissue reinforcement, although scaffolds that maintain initial tensile strength can be particularly advantageous.