A multi-lumen mold is for the in situ formation of a prosthesis in an intervertebral disc space located between adjacent vertebrae of a patient. The multi-lumen mold a flexible mold, a first lumen, a second lumen and a curable biomaterial. The flexible mold is shaped to be positioned in the intervertebral disc space. The first lumen and the second lumen each have a distal end is fluidly coupled to the flexible mold at a first location and a second location, respectively. The first lumen is shaped to extend out through a first opening extending through one of the adjacent vertebrae when the mold is positioned in the intervertebral disc space. The curable biomaterial is delivered into the flexible mold through at least one of the first and second lumens. The first and second locations can optionally be located on generally opposite sides of the mold, on the same side of the mold, or a variety of other configurations. One or more securing members can be used to secure the mold in the intervertebral disc space. The securing members can engage with the annulus, the end plates, and/or another surface of a vertebrae.