A stretchable buttress assembly includes a planar fabric layer and a biocompatible adhesive layer. The planar fabric layer is configured to stretch along a stretch axis. The planar fabric layer includes extensible fibers and non-extensible fibers. The extensible fibers are arranged in a repeatable pattern. The extensible fibers are oriented along respective paths that are each parallel to the stretch axis. The non-extensible fibers are arranged in a repeatable pattern and engaged with the extensible fibers. The adhesive layer is applied to the planar fabric and is configured to removably adhere the planar fabric layer to an end effector of a surgical stapler.