How long have the artificial disc replacements been out for the neck? Are they safe yet?
Surgeons in Europe have been using artificial disc replacements for the low back and neck much longer than in the United States. In the history of disc replacements, devices for the lumbar spine came first. When they were successful, efforts to design an equally good implant for the cervical spine were begun. The first trials using disc replacements for the neck were started in the spring of 2002 here in the U.S. Since then, more than one company has produced a cervical disc prosthesis. Studies with small numbers of patients are being reported with good-to-excellent results. One recent study from China followed a group of 25 adults who received the newer Discover implant. The implant (manufactured by DePuy) is made of titanium with a polyethylene (plastic) insert to mimic the natural disc. It is designed to restore full motion and even incorporates the lordotic angle (curvature) of the natural spine. Results were assessed 12 to 18 months later using a variety of different measures. Pain relief was good-to-excellent. Motion was improved and both measures (pain relief and motion) stayed improved throughout the follow-up period. The implants remained in good position with no evidence of subsidence (sinking down into the bone). Further studies are needed before any particular system is given the thumbs up approval by all. For example, larger groups of patients receiving the cervical disc replacement must be evaluated over a longer period of time. Studies comparing results between artificial disc replacements and the anterior cervical discectomy and fusion (ACDF) procedure will be important as well.