Implant failure following pedicle based dynamic stabilization of the lumbar spine.

Pedicle-based dynamic stabilization (PBDS) devices such as Dynesys are promoted as an alternative and less invasive option for rigid stabilization of one and even more levels of the lumbar spine. Promising features of the Dynesys system, as well as shortcomings, became obvious in several clinical studies. Since 2012, we started using a new PBDS device as an alternative for the Dynesys, to avoid the screw loosening and the kyphosing effect. The objective is to compare failure rates between the Dynesys and Balan-C type PBDS implant and factors affecting outcome. In a retrospective study we investigated a total of 90 patients with lumbar pedicle screw dynamic stabilization (a group of 64 patiënts with Dynesys stabilization is compared to a group of 26 patients with Balan-C stabilization). Mean follow-up was 48 and 38 months, respectively. Using logistic regression analysis the impact of baseline characteristics such as gender, age, body mass index (BMI), indication for surgery, primary or revision surgery, single versus more level surgery, surgeon's experience and type of the implant on implant failure was analyzed. We found a statistically significant difference in failure rates between the two systems (13% in the Dynesys group versus 62% in the Balan-C group). In multivariate analysis, type of implant was associated with implant failure (odds ratio : 13). Our current results call for an optimization of the pre-and post-marketing surveillance of pedicle-based dynamic stabilization.