Insertion loads of the X STOP interspinous process distraction system designed to treat neurogenic intermittent claudication

An interspinous process implant has been developed to treat patients suffering from neurogenic intermittent claudication secondary to lumbar spinal stenosis. As most patients who suffer from spinal stenosis are over the age of 50 and may have weaker bones, it is imperative to know how bone mineral density (BMD) correlates with lateral spinous process strength. The study was undertaken to characterize the lateral failure loads of the spinous process, correlate the failure loads to BMD, and compare the failure loads to the loads required to insert an interspinous process implant. Spinous process lateral failure loads were assessed, correlated to BMD, and compared to the loads required to insert an interspinous process implant. Mean spinous process failure loads were significantly greater than the lateral insertion load of the interspinous process implant. There was a significant relationship between the BMD and spinous process failure load. The technique used to insert the interspinous implant poses little risk to spinous process failure. There is ample margin of safety between the insertion loads and spinous process failure loads. The significant relationship between BMD and spinous process failure load suggests that patients with lower BMD must be approached with more caution during the implant insertion procedure.