Interspinous process spacer RCT
SUPPLEMENTAL DIGITAL CONTENT
Table, Supplemental Digital Content 1, Study eligibility
Key Inclusion Criteria

Age ≥ 45 years

Persistent leg, buttock, or groin pain, with or without back pain, that was relieved
by lumbar flexion

Persistently symptomatic with unsuccessful response to at least 6 months of
conservative treatment

Moderate spinal stenosis at one or two levels from L1-L5, defined as 25-50%
reduction in lateral/central foraminal diameter compared to adjacent levels, and
radiographic evidence of thecal sac and/or cauda equina compression, nerve
root impingement, and/or hypertrophic facets with canal encroachment

Zurich Claudication Questionnaire Physical Function score ≥ 2.0

Able to sit for 50 minutes without pain and to walk ≥ 50 feet
Key Exclusion Criteria

Fixed motor deficit

Concomitant surgical procedure required

Grade II or greater spondylolisthesis

Unremitting back pain in any spinal position

Significant lumbar instability, defined as ≥ 3 mm translation or ≥ 5 angulation

Active systemic disease that may affect the welfare of the patient
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Interspinous process spacer RCT

Vertebral osteopenia, osteoporosis, or history of vertebral fracture

Body mass index ≥ 40 kg/m2

Previous lumbar spine surgery

Cauda equine syndrome

Active infection

Pregnant or lactating female
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Interspinous process spacer RCT
Figure, Supplemental Digital Content 2, CONSORT flow diagram.
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Interspinous process spacer RCT
Table, Supplemental Digital Content 3, Baseline radiographic findings
Superion
X-Stop
n=190
n=201
Central stenosis
1.1
0.5
Left lateral stenosis
0.5
0
Right lateral stenosis
0.5
0
Left foraminal stenosis
0.5
0
Right foraminal stenosis
0.5
0
Central stenosis
5.3
5.0
Left lateral stenosis
4.2
4.5
Right lateral stenosis
4.2
5.0
Left foraminal stenosis
3.7
3.0
Right foraminal stenosis
3.7
3.0
Central stenosis
41.6
47.3
Left lateral stenosis
28.4
33.3
Right lateral stenosis
29.5
34.3
Left foraminal stenosis
29.5
30.3
Right foraminal stenosis
27.9
31.8
77.4
76.6
Variable
L1-L2
L2-L3
L3-L4
L4-L5
Central stenosis
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Interspinous process spacer RCT
Left lateral stenosis
52.1
55.7
Right lateral stenosis
52.6
55.7
Left foraminal stenosis
60.0
55.7
Right foraminal stenosis
60.0
55.7
Reported values are percentages. Sum of values > 100% due to more than one
diagnosis at each level in some patients.
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Interspinous process spacer RCT
Figure, Supplemental Digital Content 4, Changes in Zurich Claudication
Questionnaire over 2 years: a) Symptom Severity, b) Physical Function, and c)
Patient Satisfaction.
a.
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Interspinous process spacer RCT
b.
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Interspinous process spacer RCT
c.
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