Abstract

Purpose: Correlation of clinical outcome of X stop interspinous process decompression in patients with symptomatic lumbar spinal stenosis is made with spinal canal area change on positional MRI.

Method and Results: Clinical outcome was assessed by ZCQ, ODI, SF36 and VAS scores. There is clinically significant improvement if two ZCQ domains improved > threshold or patients were satisfied. Dural sac area was measured standing erect and sitting, neutral, flexion and extension preoperatively and at 2 years. Increased dural sac area was taken as radiological improvement.

Thirty-six patients had MRI at 2 years. Using paired t test we noted statistically significant increase in mean dural sac area in all four positions mentioned above. There was clinical improvement in 26 and some or no improvement in 10 patients. Number with increase in canal cross sectional area was 28 and that with reduced area was 8. Clinical and canal area improvement was seen in 20 (56%) patients and clinical improvement with reduced canal area was seen in 5 (14%). Some or no clinical improvement with canal area improvement occurred in 8 (22%) patients and no significant clinical or canal area improvement in 3 (8%).

Conclusions:

Majority of patients (56%) showed clinical and cross sectional area improvement at 2 years.

Interest statement: Commercial/industry support: Medtronics

Purpose: Correlation of the clinical outcome of X stop interspinous process decompression (IPD) in patients with symptomatic lumbar spinal stenosis (LSS) is made with their preoperative disc heights.

Method: 45 patients, who had clinical follow-up at 2 years, had pre-operative erect positional MRI scans. Clinical outcome was assessed by Zurich Claudication Questionnaire,ODI,SF36 and VAS scores.ZCQ is the most condition specific for LSS and was used. There is clinically significant improvement if two ZCQ domains improved > threshold (SS> 0.46, PF> 0.42, PS< 2.4) or patients were satisfied. Disc heights were measured in the standing erect posture. Osiris 4.17 software program was used for measurements. Statistics used was Chi-Square test with cross tabulation.

Results: There was clinical improvement in 33 and some or no improvement in 12 patients. Overall preoperative range of disc heights was 1.8 to 10.05 mm, median 5.93. Disc height was less than or equal to 5mm in 21 patients and it was > 5 mm in 24 patients.19 patients who had initial disc height of > 5 mm and 14 patients who had disc height of less than or equal to 5 mm had clinically significant improvement. In the group of patients who had some or no improvement the numbers were 5 and 7 respectively. We found a difference between the groups with bigger and smaller preoperative disc heights and a larger proportion of patients with bigger preoperative disc height had better clinical outcome. This difference was not statistically significant, P = 0.350.

Conclusions: The X stop device remains clinically effective at the end of 2 years in the majority of patients. Overall patients who had bigger preoperative disc heights 79% (i.e. 19/24 who had > 5mm initial disc height) had better clinical outcome compared to those with smaller preoperative disc heights.

Interest statement: Commercial/industry support: Medtronics

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.

Background: X stop interspinous decompression device has been used effectively in symptomatic patients with lumbar canal stenosis. The positional MRI scanner images patients in the erect weight bearing position and is used here to evaluate the efficacy of the X stop in maintaining increase in dural sac and foraminal areas.

Aim: To assess the clinical effectiveness of X stop in patients with lumbar canal stenosis and measure its effect in decompressing the spinal canal two years postoperatively.

Design: Prospective Observational Study.

Methods: Clinical outcome was assessed by ZCQ, VAS, ODI and SF36 questionnaires. Clinical and radiological outcomes were measured preoperatively and at 2 years. Foraminal area was measured in flexion and extension whereas dural sac area was measured in erect, neutral, flexion and extension. Osiris 4.17 software program was used for the measurements. The data was analysed using paired t test on SPSS ver.15.01.

Results: With ZCQ overall 57% of patients had clinically significant improvement at 24 months. The mean ODI and VAS scores showed improvement. The SF-36 improved in four domains. Radiologically we noted increase in mean dural sac area in all positions. There was a small increase in foraminal areas and statistically significant increase in dural sac areas at 24 months.

Conclusion: The X stop device remains clinically effective at the end of 2 years. It is a relatively less invasive procedure without major complications and can be performed as a day case procedure. X stop maintains increase in dural sac and foraminal areas at 24 months postoperatively.

Aim: To measure the effect of X-stop interspinous decompression device on the dural sac and foraminal area at 6 and 24 months post operatively at the instrumented level in patients with symptomatic lumbar canal stenosis.

Design: Prospective Observational Study of 48 patients.

Methods: Patients due to have an X stop procedure were included and had a positional MRI scan preoperatively and 6 & 24 months post operatively. Foraminal area was measured in flexion and extension position whereas dural cross sectional area was measured in erect, neutral, flexion and extension positions. Osiris 4.17 software program was used to measure the canal and foraminal dimensions. The data was analysed using paired t test on SPSS ver.15.01.

Results: Forty-eight patients (25 male and 23 female) underwent scans preoperatively and at six months. Twenty-nine patients had single level and 19 had double level procedures. Three patients had removal of X stop and 5 did not have scan at 24 months leaving 40 patients scanned at 24 months. Of these 38 scans were complete and were included. We noted increase in mean dural sac area in all positions. The mean dural sac area increased from 131 mm2 to 143 mm2 (p=0.144) at 6 months and from 137 mm2 to 202 mm2 (p= 000) at 24 months in standing position. The difference in pre-operative measurements in the six and 24-month measurements is because of the different patient numbers scanned. There were similar increased dural sac areas in the other positions. The mean foraminal areas were measured in flexion and extension and the measurements in extension were increased from 66.58 mm2 to 79.51 mm2 (p=. 001) at 6 months and from 68.10 to 69.57 mm2 (p=0.752) at 24 months on left side; and increased from 63.75 mm2 to 71.65 mm2 (p=0.036) at 6 months, from 65.54 mm2 to 68.01mm2 (p=0.440) at 24 months on right side. Thus there is a small increase in foraminal areas and statistically significant increase in dural sac areas at 24 months.

Conclusion: X-stop interspinous device remains effective in decompressing the stenosed spinal segment by increasing the anatomic dural cross sectional areas and foraminal areas of spinal canal at 24 months post operatively, thus providing symptomatic relief from lumbar canal stenosis.

Aim: To study the effect of X-stop interspinous decompression device on the lumbar spine kinematics at 6 and 24 months post operatively at the instrumented and adjacent levels in patients with symptomatic lumbar canal stenosis.

Design: Prospective Observational Study of 48 patients.

Methods: Patients due to have an X stop procedure were included and had a positional MRI scan preoperatively, 6 and 24 months post operatively in erect, flexion, extension and neutral position. Disc heights, endplate angles, segmental and lumbar spine motion was measured at stenosed instrumented and adjacent levels. Osiris 4.17 software program was used to measure the canal and foraminal dimensions. The data was analysed using paired t test on SPSS ver.15.01.

Results: Forty-eight patients (25 Male and 23 Female) underwent scans preoperatively and at 6 months. Twenty-nine patients had single level and 19 had double level procedures. Three patients had removal of X stop and 5 did not have scan at 24 months, leaving 40 patients scanned at 24 months. Of these, 38 scans were complete and were included. Mean anterior disc height reduced from 7.1 mm to 6.3 mm (p=0.004) from 48 scans at 6 months and from 7.2 mm (pre-operative) to 5.9 mm (at 24 months) – (p=0.000) from 38 scans at 24 months at the instrumented level. We hypothesise that the reduction in anterior disc heights could be a result of the interspinous distraction plus the natural progression of spinal stenosis and ageing. There was no significant change in posterior disc heights at instrumented level or adjacent levels. The mean lumbar spine motion was 22.89o, 21.3 o and 21o (p=0.183) preoperatively, 6 and 24 months respectively. The total range of movements of lumbar spine and individual segments were measured. There was no significant change in the segmental range of motion at instrumented and adjacent levels.

Conclusion: X-stop interspinous device does not significantly alter the kinematics of lumbar spine at instrumented and adjacent levels at 6 and 24 months postoperatively.

Aim: To assess the clinical effectiveness of X stop interspinous decompression device in patients with neurogenic claudication due to lumbar canal stenosis at 24 months post surgery.

Design: Prospective Observational Study of 57 patients with X stop procedure.

Methods: Fifty-seven patients with unilateral or bilateral leg pain due to lumbar canal stenosis, who had significant relief from sitting or flexing the lumbar spine, were treated with X stop.

Clinical outcome was assessed by Zurich claudication questionnaire (ZCQ), visual analogue score (VAS), Oswestery disability index (ODI) and SF36 questionnaires preoperatively and at 2 years. ZCQ has three components- symptom severity, physical function and patient satisfaction. ZCQ is considered the most precise, reliable and condition specific questionnaire for lumbar canal stenosis.

Out of 57 patients, 2 died due to unrelated causes, 3 withdrew from study and 3 had the device removed within 2 years. Forty-five, 44, 42 and 48 completed ZCQ, ODI, SF-36 and VAS respectively at 24 months.

Results: The mean age was 71(53–94) and M: F ratio 29:28. X stop device was inserted at single level in 32 (56%) and double levels in 25(44%) patients. In single level cases, 72% reported improvement in symptom severity, 65% in physical function, 68% were satisfied with the procedure, and overall 55% made a clinically significant improvement at 24 months. In double level cases, the figures were 62%, 68%, 78% and 40% respectively. The threshold for changes in symptom severity was 0.46, physical function was 0.42 and patient satisfaction 2.42. Overall clinically significant improvement requires that a patient achieves at least 2 criteria.

The mean ODI improved by 6.5 in single level and 10.8 in double level cases. The SF-36 showed improvement in physical function, role physical, bodily pain and vitality social domain.

Average hospital stay for the procedure was 1.6 days. One patient stayed for 10 days for investigation unrelated to the procedure. There were no major complications.

Conclusions: The results of our study show that the X stop interspinous decompression device remains clinically effective at the end of 2 years. X stop is a relatively less invasive procedure, especially suitable for patients with other co-morbidities, which can be performed as a day case procedure without major complications.