Monday, November 2, 2009

Dynesys: Rounding Third and Heading Home!

The FDA announced on Monday that the Dynesys Spinal System was as effective as the Silhouette Spinal Fixation System in more than 300 patients with nerve damage and spinal stenosis. If approved on Wednesday, this will be the first product approved for non-fusion use in the United States.

The success rate for patients that had the Dynesys implanted was 52% as compared to 40% for those patients that had the Silhouette implanted. The data indicated that Dynesys alleviated leg pain in 87% of the patients compared to 73% that had the Silhouette implanted. Even with this good news, there were some questions raised about potential bias in the evaluation saying a majority of the patients in the study were treated by researchers with a financial interest in the company.

The FDA released documents on Monday which stated that there might be bias from compensation when payments or stock holdings were analyzed for any influence in the proposed new use of the product. Currently, the product is marketed as an adjunct to fusion. One analysis by the FDA found a positive correlation between payments made to doctors and success rates for the device. Zimmer had no comment on the financial compensation issue. In the spirit of the World Series, Dynesys is rounding third and heading home! TSB wants to know what our readers think?


  1. I'm looking at the Summary of Safety and Effectivess and notice a couple things. I don't see anything about fusion or non-fusion. I wonder what types of 'non-fusion' claims they would be able to make.

    As you said, the rates of overall success are quite strongly weighted towards Dynesys- primarily driven by improvements in leg pain. If you go back to the adverse event table, one of the only events that shows a statistically difference is 'Back and leg pain' and it favors Silhouette (18.6% v 7.9%). That seems counter intuitive to me.

    I wonder 'why' there is such a difference in the overall success rates of these two groups.