I had a disc replacement for my neck (C5-6 level) about two years ago. I'm doing quite fine but wondering now just how long these things last. I'm sure we talked about it with the surgeon but I'm drawing a blank as to what was actually said.
Of course, no one can say for sure how long cervical disk arthroplasty (disc replacements) will last or how well they will hold up. That's for two reasons -- one, they haven't been around that long to see what happens. And two, most of the studies published so far only go out two to four years.
There is a recent study from France using the Bryan disc replacement system with reported results eight years out. The Bryan disc system mimics the normal protective disc that acts like a cushion between two vertebral bodies. It is made of titanium on the outside with a plastic inside. The titanium endplate shells are covered in a double layer of porous coating to allow for better grip between the vertebrae.
Everyone in the study had good spinal alignment without any sign of instability. They had all tried conservative care without good enough results to bypass surgery. Patients ranged in age from 26 to 65 years old.
Results were measured using a variety of outcomes such as work status, activity level, symptoms (neck and/or arm pain), and neck motion. X-rays were used to assess the position of the device and to look for heterotopic ossification (HO).
With heterotopic ossification, there is additional bone formed outside the skeletal system. The extra bone usually forms in the surrounding soft tissues, especially the nearby muscles. It's a problem because the artificial disc replacement (ADR) is designed to maintain joint motion. The heterotopic ossification reduces soft tissue mobility and causes increased stiffness.
The eight-year results were excellent. Three-fourths of the patients (18 of the 21) were free of neck and/or arm pain. They could perform all daily activities and chores without any problems. There were no neurological symptoms (e.g., no numbness or tingling down the arms, no change in deep tendon reflexes or sensation).
Heterotopic ossification (HO) was a problem in almost half of the patients. More HO seems to develop as time goes by. Not only do more patients show evidence of HO in time, those who develop it early start to progress to more severe cases. Having a two-level disc replacement is also a risk factor for HO.
As far as the other common complications developing (loosening, migration, subsidence, implant failure), there were none! There were three cases of spontaneous fusion (bone filling in around the implant) but no symptoms or functional problems as a result. No one had any further follow-up surgery.
About 19 per cent of the group did develop adjacent segment disease (ASD). That's a striking finding since it has been believed that fusion is what causes increased degeneration at the vertebral segments on either side of the fusion. There is some speculation that ASD develops because there were already some degenerative changes present before disc replacement.
In conclusion, artificial disc replacement for the cervical spine (neck) is safe and effective. But it may not be without its problems. It's good that you have had such excellent results. Keep up with your follow-up appointments and watch for more suggestions and guidelines as other long-term studies are published.