Compositions and methods are provided for preparing an adhesion barrier in the form of a foldable or flexible biodegradable polymer matrix that effectively reduces, prevents or treats adhesions in a patient in need thereof. In one embodiment, the matrix comprises a first porous layer comprising collagen and a second porous layer comprising collagen and dextran, wherein the dextran is loaded in the second layer in an amount of from about 5% to about 90% by weight based on a total weight of the matrix. In some embodiments, the matrix prevents or reduces cell growth into the matrix so as to reduce or prevent adhesions. In some embodiments, the matrix is in a sheet or strip form that can be folded into a tube form.
