A system for repairing an intervertebral disc by delivering and curing a biomaterial in situ within the disc. The system includes both a device, having an insertable balloon and related lumen, controls and adapters, as well as an in situ curable biomaterial (and related biomaterial delivery means). The system can allow the doctor to determine a suitable endpoint for biomaterial delivery, by controlling distraction and/or biomaterial delivery pressure, and in turn, to deliver a desired quantity of biomaterial to the balloon in order to achieve improved polymer cure and implant characteristics. Also provided is a related method for repairing an intervertebral disc by using such a system to deliver and cure the biomaterial in situ. The system can be used to implant a prosthetic total disc, or a prosthetic disc nucleus in a manner that leaves the surrounding disc tissue substantially intact.