A study published in the March 15 issue of the journal Spine shows that the majority of patients who were implanted with the CHARITÉ Artificial Disc between 1989 and 1995 continue to have less pain and more mobility as much as 16 years after the procedure. The CHARITÉ Artificial Disc made by DePuy Spine (Raynam, Massachusetts), a business of Johnson & Johnson (New Brunswick, New Jersey), is the first FDA-approved artificial disc (October 2004). Iterations have been available worldwide for more than 17 years.
The retrospective study examined the safety and effectiveness of the CHARITÉ Disc in 108 patients operated on by study author Thierry David, MD, an orthopedic spine surgeon with the Department of Orthopaedics Polyclinique De Bois Bernard (Rouvroy, France). The patients all had one-level (either at L4 - L5 or L5 - S1) lumbar degenerative disc disease and had failed non-operative treatment.
Patients were followed for a minimum of 10 years and up to 16.8 years. The study reports that 87 (82.1%) patients experienced "excellent or good" clinical outcomes, prosthesis mobility was 90.6% and that nearly 90% of patients eligible to work before surgery returned to work, more than three-quarters to hard labor. The average range of motion in flexion-extension was 10.1 degrees and lateral bending was 4.4 degrees.
"The patients in this series continue to do well after many years," said David. "The results are encouraging since it's been more than 10 years since these patients had an implant and since then the instrumentation and techniques to implant the disc continue to evolve, as has the criteria for patient selection."
David also reported that the rate of post-operative complications is "certainly lower than fusion if transition syndrome [or adjacent level disease] is considered a complication of fusion."
The rate of adjacent level disease requiring surgical intervention was about 10 times lower (2.8%) for CHARITÉ patients, compared with some reports on the incidence of transition syndrome in the literature for lumbar fusion. In addition, the overall rate of re-operation was 10.4%, which included eight index-level fusion procedures and three prosthesis replacements.
"The reduction in adjacent level disease may be the most interesting finding as it helps support the primary reason why I believe in total disc replacement," said Dr. Fabien Bitan, chief of spine surgery at Lenox Hill Hospital (New York), who consults for DePuy. "Adjacent level disease as a result of fusion is something that sometimes gets overlooked and, if possible, needs to be dramatically reduced by the spine community. Total Disc Replacement instead of fusion is one way to try and do that."
There were 63 females and 45 males in the study with an average age of 36.4 years (range, 23-50); 82 patients were treated at L5 - S1 and 25 at L4 - L5 and one at L3 - L4.
A single case of core failure occurred at 9.5 years following surgery. Laboratory analysis indicated that shear forces and a high level of oxidation were likely contributors to this failure.
The polyethylene cores of all CHARITÉ Discs sold in the U.S. since the device became available for commercial distribution are sterilized using DePuy's proprietary Gamma Vacuum Foil process, designed to reduce the incidence of on-shelf oxidation.
Patients receiving the CHARITÉ Artificial Disc should have failed at least six months of conservative treatment prior to implantation of the CHARITÉ Artificial Disc.