A method of replacing a nucleus pulposus material wherein curable nucleus pulposus material is injected into a balloon in an intervertebral space. The balloon has an inlet port and an outlet port that are connected to a pressure-measuring device. After the catheter is placed in the intervertebral space, the balloon is filled with a radio-opaque solution until the desired balloon volume is attained. The nucleus replacement material is then fed into the inlet port of the balloon, while the radiopaque agent is allowed to leave via the outlet port. Once the balloon is completely filled and curing of the curable nucleus replacement material is accomplished, the catheter and ports are removed, and the annular defect can be sealed.
