An interbody fusion cage comprised of two support elements that separate after insertion into the interbody space to form a pocket into which graft material may be inserted. The expansion of the support elements deploys ribbons between the two support elements to further insulate the pocket into which the graft material is inserted, thereby holding it securely in place. Ribbons may be formed of a flexible material so that graft material can be inserted by a surgeon above or below them. Ribbons may also be deployed manually by the surgeon so as to allow insertion of graft material before the ribbon is deployed.