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