Artificial disc compares favorably with fusion

By Mary Ann Porucznik

Artificial cervical disc replacement has recently become an option for treatment of the patient with cervical radiculopathy. According to the presenters of Paper 109, disc replacement using the Bryan artificial cervical disc compares favorably to a conventional anterior cervical discectomy and fusion (ACDF) for the treatment of patients with cervical radiculopathy.

Based on this prospective, randomized study, two out of three patients (67 percent) who received the artificial disk reported excellent results at six weeks, compared to just 44 percent of fusion patients. “The investigational group continued to perform better at all times up to and including 1-year postoperative, where 84 percent of the Bryan disc recipients had excellent results compared to just 64 percent of the fusion group,” reported the authors.

Preoperative neck pain scores of 72 dropped to 19 postoperatively in the artificial disc group, versus 28 in the ACDF group at 12 months. At 24 months, patients in the artificial disc group had a pain score of 19, compared to 36 in the fusion group (p=0.012). Patient satisfaction was also higher in the artificial disc group at 1 year, and success rates as determined by the SF-36 scores were equivalent in both groups. No significant adverse events were reported in the artificial disc group.

Previous studies have retrospectively evaluated the efficacy of the Bryan artificial cervical disc without the scientific rigor of a concurrent control population and conventional surgical techniques. The authors presented pooled data from three surgeons involved in the U.S. Food and Drug Administration’s Investigational Device Exemptions clincial trial evaluating the Bryan artificial cervical disc.

The study involved 115 patients who were randomized to either the Bryan artificial disc replacement (56) or an anterior cervical fusion with allograft and a plate (59). The Bryan group included 30 males and 26 females, with an average age of 43 years; the fusion group was comprised of 32 males and 27 females, with an average age of 46 years.

Compared to the ACDF group, the Bryan group had a longer average operative time (1.7 hours vs. 1.1 hours), greater blood loss (64 cc vs. 50 cc) and a slightly longer hospital stay (0.9 days vs. 0.6 days). Two patients required an intraoperative conversion from the prosthesis to fusion. However, at both 1- and 2-year follow-up, the Bryan group had lower levels of neck disability and pain with greater range of motion and higher functional scores than the control group, as shown in the table.

As expected, significantly more motion was retained in the disc replacement group than the plated group at the index level (p<0.006 at 3, 6, 12, and 24 months). The disc replacement group had preoperative motion of 6.5 degrees and retained an average of 7 degrees at 24 months. In contrast, the average range of motion in the fusion group was 8.1 degrees preoperatively and gradually decreased to 0.85 degrees at 24 months.

“What is most impressive is that at the 2-year follow-up, there is statistically significant improvement in the artificial disc group compared to the fusion group as measured by the Neck Disability Index, neck VAS and the SF-36 physical component. It appears the Bryan disc is at least as safe and effective as ACDF for treatment of single-level degenerative disc disease in the hands of a capable surgeon,” write the authors. “In addition, the disc has the added benefit of allowing normal cervical motion with potentially decreased future morbidity.”

The authors include Rick Sasso, MD, of Indianapolis; John Heller, MD, of Atlanta; Robert Hacker, MD, of Eugene, Ore., and John W. Powell, MD, of Iowa City, Iowa. Drs. Sasso, Heller and Hacker received research support from Medtronic.

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