I am going to get a myelogram with full spinal fusion. i am worried that they won't be able to insert the needle correctly. are there any risks in terms of the needle/dye and my hardware?

Depends : It may be more difficult. It depends on the degree and type of fusion. Usually the metal screws and rods are along the sides of the spine so that the medial region is more accessible. The neuroradiologists are pretty good at this and do these under fluorography (x-ray guidance) so they can manuever the needle away from the metal or the fusion mass.

Myelogram: Prior surgery in the lumbar spine can create difficulties in needle placement if a myelogram is needed. Rather than attempting to locate a gap in the fusion to place the needle, an alternate approach is to perform a c1-2 puncture in the cervical spine and allow the contrast dye to travel downward from the neck. For a neurosurgeon, the technique is simple as the patient is kept upright not prone.

Should be ok: Because fluoroscopy is used, they should be able to get it done.