In this article, a group of surgeons from China report on 120 patients who were either treated with a cervical (neck) spine fusion or disc replacement. Everyone in the study had a diagnosis of painful cervical disc disease. They were randomly placed in one of these two treatment groups. The entire group was very similar in terms of preoperative age, level treated, and symptoms (neck and/or arm pain, loss of motion, disability).
Before giving us the details of the surgeries and results, the authors offered a brief summary of what is known so far about the use of artificial disc replacements. Most of the studies have been done in the United States and Europe. This is the first study looking at the Chinese population.
Before artificial disc replacements (also called cervical disc arthroplasty) were developed, patients with chronic neck pain and instability were treated with neck fusion. The fusion stopped motion at the diseased level and thus reduced pain. But the strain on the adjacent spinal levels contributed to further disc degeneration. This is considered a negative consequence of spinal fusion procedures.
Disc replacement preserves motion without putting increased stress on the spinal segments on either side of the disc replacement. Over the years, several companies have made different types of implants. The three major disc replacement devices currently on the market include: 1) BRYAN cervical disc, 2) ProDisc-C, and 3) Bristol Disc. Two of these products (BRYAN and Bristol Disc) are made by the same company (Medtronic).
In this study, the group receiving a cervical disc implant were given the BRYAN cervical disc. The group having a fusion were treated with the Anterior Cervical Deompression and Fusion (ACDF) technique. Results were compared over a two-year period of time. Pain, motion, and disability (measured by the Neck Disability Index) were compared between the two groups. Operation time, blood loss, and length of time in the hospital were also recorded and compared.
As expected, patients with the implant had more motion than the fusion group. Levels of pain and changes in neck disability from before to after surgery were not different between the two groups. They found the surgery to put in the disc replacement took much longer than a fusion procedure. And there were some unexpected complications in the disc replacement group including excess bone formation (called heterotopic ossification) and loss of lordosis (natural neck curve).
Overall results were similar to outcomes reported in other studies making the same comparison between artificial disc replacement and neck fusion. The authors concluded that using the BRYAN disc replacement is an acceptable alternative to neck fusion for adults with painful and unstable cervical disc disease.
Although anterior cervical decompression and fusion (ACDF) is still the most common surgical procedure used in China for this condition, more and more surgeons are considering using disc replacements. More studies like this are needed to confirm the success of the artificial implants instead of the fusion procedure.
Since this was the first study in China and results so far are only short-term (two years), the authors suggested further long-term follow-up over the next 10 years. Attention should be paid to whether the spinal motion and mechanics at the level where the disc was put in is preserved and maintained. Efforts should be made to monitor adjacent levels (above and below the artificial disc) for break down (and especially faster deterioration than expected).