It is distinctly uncommon to have any significant pain in a well working ADR. Motion at C6-7 was probably limited before the ADR and that could have been one of the reasons for failure (if that is even the presenting problem). You can use the flexion-extension films now (you need them) and measure the current motion of C6-7. That will give you an idea of any loss of motion but i expect you have little to no motion at that level now if the disc has failed.
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.