Interspinous Process Distraction Research Articles

P20. Positional MRI changes in the lumbar spine following insertion of a novel interspinous process distraction device

BACKGROUND CONTEXT: Clinical, radiologic, and cadaveric studies have demonstrated reduction in area of the dural sac and exit foramina as the lumbar spine moves from flexion into extension. Patients with spinal stenosis develop symptoms of radiculopathy and/or neurogenic claudication in erect or extended postures which are relieved by sitting or stooping. Clinical studies on the X-Stop device have shown improvement in the claudication outcomes. The device can be implanted under local anaesthetic, avoiding the high morbidity or mortality associated with spinal decompressions and/or fusions.

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.

Interspinous devices for lumbar stenosis – a review of the literature

Interspinous process distraction devices are emerging as a treatment for lumbar spinal canal and foraminal stenosis. Lifetime risk is around 10%. The number of patients who could potentially benefit from such surgery is large and is projected to rise. A literature search was undertaken of relevant bibliographic databases, limited to four main languages. High level searching was performed using relevant web-based resources. . The literature review indicated that interspinous devices are effective, in the short term, in treating claudication related to spinal stenosis. There was however, a lack of medium and long-term outcome data, particularly with respect to durability of symptom relief and the risks of device migration or dislocation. There was also little published comparison against alternative conventional surgery. Interspinous devices are a promising new technology, the results of longer-term clinical follow-up studies are needed to define more clearly their role in the management of lumbar spinal stenosis.

The conservative surgical treatment of lumbar spinal stenosis in the elderly.

Canal stenosis is now the most common indication for lumbar spine surgery in elderly subjects. Degenerative disc disease is by far the most common cause of lumbar spinal stenosis. It is generally accepted that surgery is indicated if a well-conducted conservative management fails. A meta-analysis of the literature showed on average that 64% of surgically treated patients for lumbar spinal stenosis were reported to have good-to-excellent outcomes. In recent years, however, a growing tendency towards less invasive decompressive surgery has emerged. One such procedure, laminarthrectomy, refers to a surgical decompression involving a partial laminectomy of the vertebra above and below the stenotic level combined with a partial arthrectomy at that level. It can be performed through an approach which preserves a maximum of bony and ligamentous structures. Another principle of surgical treatment is interspinous process distraction This device is implanted between the spinous processes, thus reducing extension at the symptomatic level(s), yet allowing flexion and unrestricted axial rotation and lateral flexion. It limits the further narrowing of the canal in upright and extended position. In accordance with the current general tendency towards minimally invasive surgery, such techniques, which preserve much of the anatomy, and the biomechanical function of the lumbar spine may prove highly indicated in the surgical treatment of lumbar stenosis, especially in the elderly.