State of the art and advances in Interspinous implants

Author(s): MAREK SZPALSKI, ROBERT GUNZBURG, ROBERT J. MOORE, CHRISTOPHER J. COLLOCA

Lumbar spinal stenosis is a common condition in elderly patients and also one of the most common reasons to perform spinal surgery at an advanced age. Classical treatment is based on wide or limited surgical decompression, procedure for which many variants have been reported. However it can be a heavy intervention in elderly patients and carries a risk of iatrogenic instability. Lumbar stenosis is a dynamic phenomena as the diameter and surface of the spinal canal decreses during sagittal extension due to bulging of the disc. The rationale of the interspinous implants is to restrain extension thus avoiding the occurrence of neurogenic claudication. Over the time, however, their indications have widened to other degenerative conditions. In vitro studies have showed an effect of intradiscal pressure and unloading of facet joints. Evidence remains, however sparse as to their effectiveness. There is limited clinical evidence as to their results in spinal stenosis but not much in other indications. The use of a tension band has been reported but its true effect never truly analyzed. In an in-vivo animal study we reported the effect of a novel interspinous device with an added tension band on segmental instability. It decrease abnormal flexion motion and restores spinal stiffness.