A flexible piece of barrier material for use in preventing or minimizing adhesions and fibrous attachments following anterior lumbar surgery. In one embodiment, the barrier structure comprises a multiple level device shaped as a generally wider tongue to function as a barrier at or above the L4-5 level, and a generally narrower lower section to function as a barrier at or below the L5-S1 level. The structure also can include a recessed waist section along an edge opposite the tongue to allow for easier placement in the L4-5 area. In another embodiment, a single level barrier for use at or above L4-5 is shaped as a tongue with a tapered outer extension to allow the barrier to extend laterally onto the psoas muscle to provide for identification of the barrier upon reoperation.
