Abstract
The clinical outcome of patients with symptomatic lumbar spinal stenosis (LSS) was assessed during a follow-up period of 2 years after X-Stop implantation. The X-Stop is the most commonly used interspinous distraction device in patients with neurogenic intermittent claudication due to LSS. Between 2003 and 2007, more than 1,000 patients were examined in our centre with symptoms of intermittent claudication due to spinal stenosis. Between February 2003 and June 2007, in 175 of these patients an X-Stop device was implanted in one or two levels. Patients were clinically evaluated regularly during a follow-up period of up to 4 years using the VAS (leg pain) score and the Oswestry disability index. The mean VAS (leg pain) score in these 175 patients was reduced from 61.2% preoperatively to 39.0% at the first clinical follow-up examination at 6 weeks postoperatively. The mean VAS score at 24 months postoperatively was 39.0%. Oswestry score was 32.6% preoperatively, 22.7% at 6 weeks, and 20.3% at 24 months postoperatively on average. In eight out of the implanted 175 patients, the X-Stop had to be removed and a microsurgical decompression had to be performed because of unsatisfactory effect of the interspinous distraction device. Our single-centre results indicate not only a satisfactory short-term, but also a good long-term effect during a follow-up period of 2 years. Functional MRI examinations provide helpful, positional-dependent preoperative information. More than any radiological feature, the typical clinical picture of positional-dependent claudication with a relief of symptoms during flexion is the most important factor for appropriate patient selection. The interspinous device does not replace microsurgical decompression in patients with massive stenosis and continuous claudication, but offers a save, effective and less invasive alternative in selected patients with spinal stenosis. Concerning the operative technique, a minimally invasive implantation with preservation of the interspinous ligament is appropriate. Functional (upright-) MRI examinations were able to demonstrate the positional-dependent stenosis. If available, fMRI represents the most helpful radiologic examination in assessing the outcome of interspinous spacer implantation.