Dynesys dynamic stabilization: less good outcome than lumbar fusion at 4-year follow-up.

Dynamic semirigid stabilization of the lumbar spine was introduced in 1994 in an attempt to overcome the drawbacks of fusion. It is supposed to preserve motion at the treated levels, while avoiding hypermobility and thus spondylosis at the adjacent levels. Although the early reports showed promising results, the long term effects are still debated. We retrospectively compared outcomes of Dynesys dynamic stabilization with those of the traditional fusion technique. Thirty-two patients who had undergone Dynesys between 2004 and 2006 (group 1) were compared to 32 patients who had been treated with fusion between 2005 and 2006 (group 2). VAS for back and leg pain, and ODI improved significantly in both groups (p < 0.001). These scores were all better in the fusion group, and even significantly so as far as VAS for back pain was concerned (p = 0.014). Similarly, more patients were satisfied or very satisfied after fusion than after Dynesys: 87.5% versus 68.8% (p = 0.04). Interestingly, in the Dynesys group scatter plot graphs showed a positive correlation between older age and improvement in the two VAS scores and in ODI. Dynamic stabilization with Dynesys remains controversial. Older patients are relatively more satisfied about it, probably because of their low level of demands.