Change of radiological parameters after interspinous implantation (X-stop®) in degenerative spinal stenosis.

OBJECT: This study was intended to objectively demonstrate the effect of interspinous implantation through preoperative and postoperative radiological analyses in degenerative lumbar spinal stenosis.

METHODS: This study included 20 segments of 14 cases that had been diagnosed as spinal stenosis through physical and radiological findings and had interspinous implantation (X-stop(®)). On simple radiography, height and width of the intervertebral foramen, height of the anterior and posterior intervertebral disks, and interbody angle were measured. On magnetic resonance imaging (MRI), the intervertebral foramen and intradural areas were also measured. Changes in preoperative and postoperative measurements were compared, and correlation between radiological indicators was identified. Clinical evaluation was done using visual analog scale (VAS) and Oswestry disability index (ODI) scores. The relationship between the clinical outcomes and radiological changes was also evaluated.

RESULTS: The comparison of preoperative and postoperative radiological measurements showed significant changes in height and width of the intervertebral foramen, and interbody angle on simple radiography, and in height of the intervertebral foramen on MRI. Regarding correlation between radiological indicators, there was correlation between height of the intervertebral foramen on simple radiography and area of the intervertebral foramen on MRI, and between the intervertebral foramen and intradural areas on MRI. For correlation between the clinical improvement level and the changes in radiological parameters, VAS correlated with intervertebral foramen height on simple radiography and increased area of the intervertebral foramen on MRI. However, for ODI, there was no factor showing significant correlation.

CONCLUSIONS: In patients with degenerative spinal stenosis showing neurogenic claudication, interspinous implantation was more effective in increasing the height and area of the intervertebral foramen than in increasing intradural area, and the short-term clinical results were promising.