An article of footwear includes an upper, a midsole attached to the upper, and an outsole. The midsole has a footbed and a bottom surface disposed on an opposite side of the midsole than the footbed. The outsole has a ground-engaging surface, an inner surface disposed on an opposite side of the outsole than the ground-engaging surface, and a wall extending from the ground-engaging surface and surrounding the outsole. The article of footwear also includes a casing containing particulate matter and having a length that is greater than a length of the outsole. The casing includes a first fold at a predetermined location along its length. The casing is received within a cavity bounded by the wall of the outsole and between the bottom surface and the inner surface.