Abstract
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
The abstracts were prepared by Mr Matt Costa and Mr Ben Ollivere. Correspondence should be addressed to Mr Costa at Clinical Sciences Research Institute, University of Warwick, Clifford Bridge Road, Coventry CV2 2DX, UK.
