Abstract
Background: The X stop interspinous process decompression device has been used effectively in symptomatic lumbar spinal stenosis. It holds the spinal segment in a flexed position maintaining increase in dural sac and foraminal areas.
Aim: To study the effect of X-stop on the lumbar spine kinematics at 24 months post operatively at the instrumented and adjacent levels.
Design: Prospective Observational Study of 48 patients.
Methods: Patients had a positional MRI scan preoperatively, 6 and 24 months post operatively in erect, flexion, extension and neutral positions. Disc heights, endplate angles, segmental and lumbar spine motion were measured at stenosed instrumented and adjacent levels. Osiris 4.17 software program was used for measurements. The data was analysed using paired t test on SPSS ver.15.01.
Results: 48 patients underwent scans preoperatively. At 2 years 40 patients were scanned (3 patients had removal of X stop and 5 were not scanned). Of these, 38 scans were complete. Mean anterior disc height reduced from 7.2 mm to 5.9 mm (p< 0.001) at 24 months at the instrumented level. There were no significant changes in posterior disc height at instrumented or adjacent levels. The mean lumbar spine motion was 22o and 20o (p=0.366) in single level cases and 24.5o and 22.8o (p=0.547) in double level cases preoperatively and at 24 months. There was no significant change in the segmental range of motion at instrumented or adjacent levels.
Conclusion: X-stop device does not significantly alter the kinematics of lumbar spine at instrumented or adjacent levels at 24 months postoperatively.
Correspondence should be addressed to SBPR at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England.
