This was a question posted recently on the Spinal Patient Society Forum. For those interested in this topic, here is my response to this solid inquiry:
Neck patients benefit greatly from cervical adjustments. Obviously the fused segment can be mobilized, but the segments above and below, which are often forced to compensate for the lack of motion created by the fused joint, do need to be checked to insure regular motion. More commonly, fusion patients will experience pain in the middle back, and between the shoulders, because of significant restriction in that area.
In addition to mobilization, (adjusting) of the middle back, many patients who have had fusions really require stabilization of the cervical spine as much, if not more than additional mobilization (adjustments).
Look for a chiropractor who can address the complexities of working with patients who have had cervical fusions.