US Patent 7220282 Annulus-reinforcing band

A pliable band or hoop that is flexible to normal handling, but cannot stretch circumferentially once it has reached the limits of its circumferential length. The band may have a structural portal to be used for filling, or it may simply be constructed of a fabric-like material that allows a fill tube to perforate its walls to allow for filling. In the latter case, the perforated wall tends to self-seal once the fill tube is withdrawn. The band may be flat or tubular in cross-section. However, unlike a balloon, the band does not require either a bottom or a top, as we found that a top and bottom are unnecessary when using a band or hoop to enclose material injected into a reamed out intervertebral space.