Influence of X stop on neural foramina and spinal canal area in spinal stenosis

Study Design. Measurements of cross sections of exit foramen and spinal canal were performed before and after placement of X Stop in physiologic postures using positional MR scanner at the stenosed level in patients with lumbar spinal stenosis. Objective. To quantify the effect of the implant in vivo on the lumbar spine at the instrumented levels in various postures. Summary of Background Data. Dimensions of the spinal canal and neural foramen decrease from flexion to extension. Symptoms of spinal stenosis occur typically in standing or extension. The X Stop device is designed to distract the posterior elements of the stenotic segment and place it in flexion to treat neurogenic claudication. We think that the device will improve the dimension of the canal in standing and extension. Methods. Twenty-six patients with lumbar spine stenosis underwent a one- or two-level X Stop procedure. All had preoperative and postoperative positional MRI in standing, supine, and sitting flexion and extension. Measurements were carried out on the images acquired. Results. Significant increase in the dimensions of the neural foramen and canal area were demonstrated after surgery. Conclusions. The X Stop device improves the degree of central and foraminal stenosis in vivo.