An assembly for sealably injecting a fluent material into an intradiscal space accessed through an opening in the annulus of a spinal disc comprises a cannula having a passageway for injecting the fluent material therethrough into the intradiscal space, a seal having a sealing surface for sealing engagement with the outer surface of the disc annulus and defining a central opening for, and an articulating joint defined between the central opening of the seal and the cannula configured to permit relative articulation between the components. The assembly may further comprise an anchor element extending through the central opening of the seal, the anchor element including an elongated threaded body sized for threaded engagement within the opening in the disc annulus and having a head configured to engage a distal end of the cannula.