Fig. 2. Implementation of the anisotropic hyperelastic constitutive material model requires determination of prevailing fiber orientations. Fiber directions for the ligaments were assumed to align with the long-axis of the tissue. These directions were defined as a continuous element-by-element function, resulting in smooth transitions between sections with varying initial geometry as well as during large-scale deformations during the simulation. Shown here are representative sections of a 7 mm ACL graft, demonstrating the continuation of fiber direction (small black arrows) along the long axis of the ligament.