Interspinous Spacers for Lumbar Spinal Stenosis

Neurogenic claudication secondary to lumbar spinal stenosis (LSS) generally responds to conservative measures, but individuals with persistent symptoms or significant functional disability often require surgical intervention. Interspinous spacers (ISSs) have been introduced as a novel method for reproducing the postural relief that these individuals typically experience with lumbar flexion, which may avoid much of the morbidity of other operative procedures, such as a laminectomy. By distracting the interspinous space, ISSs have been shown to increase the dimensions of the spinal canal and foramina, thereby bringing about an “indirect” decompression of the neural elements. There is only one implant currently approved by the Food and Drug Administration for the treatment of intermittent neurogenic claudication arising from 1 or 2 levels of LSSs confirmed by appropriate imaging studies. As part of the surgical technique, the patient must be maintained in maximum flexion to facilitate the safe placement of the implant, and care must be taken to adequately preserve the interspinous ligament. Multiple in vitro and clinical investigations have established the safety and efficacy of ISS, but these devices are known to be associated with a number of complications, including spinous process and neurologic sequelae. Although additional prospective clinical trials are necessary to establish the long-term durability and cost-effectiveness of ISS, this strategy remains a viable, less invasive option for the treatment of symptomatic LSS compared with posterior decompression.