A sterile, non-bioabsorbable material intended to be implanted into an intervertebral disc to function as a bulking agent for the treatment for degenerative disc disease (DDD). It is made of a hydrophilic polymer (e.g., hydrogel) and is typically injected or surgically implanted into the diseased disc in a minimally-invasive procedure. It may have radiopaque markers to enable verification of the position by fluoroscopy. Disposable devices associated with implantation (e.g., introducer needles, trocars) may be included.