A Prospective, Multi-Center, Randomized Study Comparing the VertiFlex® Superion™ Interspinous Spacer (ISS) to the X-STOP® Interspinous Process Decompression (IPD®) System in Patients With Moderate Lumbar Spinal Stenosis
Phase: NA
Conditions: Lumbar Spinal Stenosis, Intermittent Claudication
Sponsor: Boston Scientific Corporation

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
 
The SPACER Trial - Investigator Protocol Signature Page 
 
Title: A Prospective, Multi-center, Randomized Study Comparing the VertiFlex® Superion® 
Interspinous Spacer (ISS) to the X-STOP® Interspinous Process Decompression (IPD®) 
System in Patients with Moderate Lumbar Spinal Stenosis – Continued Follow-Up 
 
Short Title:  The SPACER Trial 
Superion® Post-Approval Continued Evaluation and Review 
 
 
Protocol # 08-VISS-01 
19 June 2015 
 
Sponsor:  
VertiFlex®, Inc. 
1351 Calle Avanzado, Suite 100 
San Clemente, CA 92673 
USA 
 
By signing this page, the Investigator acknowledges that: 
He/she has read the protocol and agrees to comply with the protocol in accordance with 21 CFR 
Parts 50, 54, 56 and 812; Good Clinical Practices and use of the investigational products as 
indicated. 
All subjects have provided signed Informed Consent prior to enrollment in the study. 
All data relevant to the clinical evaluation and regarding the subject response and safety will be 
documented and forwarded to the Sponsor. 
All unanticipated adverse device effects and serious adverse device effects will be reported as 
requested to the Sponsor within 24 hours. 
The investigational products supplied by the Sponsor for this study protocol were used only for 
subjects enrolled for treatment under this protocol, and unused devices will be returned to the 
Sponsor at the close of the study or sooner as determined by the Sponsor.  
 
 
 
 
 
 
 
 
Signature of Investigator 
 
Date 
 
 
 
 
 
 
Printed Name of Investigator 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
 
Clinical Investigational Plan (CIP) 
 
 
 
A Prospective, Multi-center, Randomized Study Comparing the VertiFlex® Superion® 
Interspinous Spacer (ISS) to the X-STOP® Interspinous Process Decompression (IPD®) 
System in Patients with Moderate Lumbar Spinal Stenosis – Continued Follow-Up 
 
Short Title:  The SPACER Trial 
Superion® Post-Approval Continued Evaluation and Review 
 
 
 
Protocol # 08-VISS-01 
19 June 2015 
 
 
VertiFlex®, Inc. 
1351 Calle Avanzado, Suite 100 
San Clemente, CA 92673 
USA 
 
 
 
 
 
This document is a confidential communication of VertiFlex®, Inc. The recipient agrees that no 
unpublished information contained herein will be published or disclosed without prior written 
approval of VertiFlex®, Inc. except that this document may be disclosed to appropriate ethics 
committees or duly authorized representatives of the U.S. Food and Drug Administration or other 
responsible regulatory authorities under the condition that confidentiality is maintained. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 3 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Table of Contents 
 
The SPACER Trial - Investigator Protocol Signature Page ....................................................1 
Table of Contents ......................................................................................................................3 
Protocol Summary Page............................................................................................................5 
Principal Study Contacts ........................................................................................................ 11 
1 
Introduction and Background ........................................................................................ 12 
1.1 
Introduction ............................................................................................................... 12 
1.2 
Rationale for this Investigation  ................................................................................. 13 
2 
Device Name .................................................................................................................... 14 
3 
Intended Use of the Device .............................................................................................. 14 
4 
Device Description ........................................................................................................... 14 
4.1 
Superion® Interspinous Spacer (ISS) – Study Device ................................................. 14 
4.2 
X-STOP® Interspinous Decompression (IPD®) System – Control Treatment .............. 16 
5 
Study Overview ............................................................................................................... 16 
5.1 
Purpose ...................................................................................................................... 16 
5.2 
Study Endpoints......................................................................................................... 16 
5.2.1 
Composite Endpoint (Primary) – Individual Patient Success ................................ 16 
5.2.2 
Secondary Endpoint ............................................................................................. 17 
5.2.3 
Safety Endpoints and Role of CEC ....................................................................... 17 
5.2.4 
Other Endpoints ................................................................................................... 17 
5.3 
Study Hypothesis ....................................................................................................... 17 
5.4 
Duration and Extent of Investigation .......................................................................... 18 
6 
Study Design .................................................................................................................... 18 
6.1 
Study Population and Source of Subjects ................................................................... 20 
6.2 
Randomization ........................................................................................................... 20 
6.3 
Subject Eligibility Criteria ......................................................................................... 20 
6.3.1 
Inclusion Criteria ................................................................................................. 20 
6.3.2 
Exclusion Criteria ................................................................................................ 21 
6.4 
Study Enrollment ....................................................................................................... 22 
6.5 
Study Procedures ....................................................................................................... 23 
6.5.1 
Screening ............................................................................................................. 23 
6.5.2 
Baseline Assessment ............................................................................................ 23 
6.5.3 
Randomization and Enrollment ............................................................................ 24 
6.5.4 
Post-Procedure Visits ........................................................................................... 24 
7 
Termination of Subject Participation ............................................................................. 26 
8 
Study Deviation ............................................................................................................... 26 
9 
Adverse Events ................................................................................................................ 27 
9.1 
Definitions ................................................................................................................. 27 
9.2 
Anticipated Adverse Events ....................................................................................... 28 
9.3 
Subsequent Surgical Interventions ............................................................................. 28 
9.4 
Device Explant and Retrieval ..................................................................................... 29 
10 Statistical Considerations and Methodology .................................................................. 29 
10.1 
Clinical Trial Objective.............................................................................................. 29 
10.2 
Primary Outcome ....................................................................................................... 29 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 4 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
10.3 
Randomization ........................................................................................................... 30 
10.4 
Analysis Populations ................................................................................................. 30 
10.5 
Primary Statistical Analysis ....................................................................................... 30 
10.6 
Superiority ................................................................................................................. 31 
10.7 
Missing Data and Loss To Follow-up......................................................................... 31 
10.8 
Stratified Analysis for Multiple-Level Analysis ......................................................... 31 
10.9 
Secondary Endpoints ................................................................................................. 32 
10.10 Safety Analyses ......................................................................................................... 32 
10.11 Site Heterogeneity ..................................................................................................... 32 
11 Risks ................................................................................................................................. 32 
12 Benefit Analysis ............................................................................................................... 34 
13 Investigator Responsibilities ........................................................................................... 35 
13.1 
IRB Approval ............................................................................................................ 35 
13.2 
Protocol Adherence ................................................................................................... 35 
13.3 
Review of Source Documents .................................................................................... 35 
13.4 
Record of Device Inventory ....................................................................................... 35 
13.5 
Data Recording and Record Retention ....................................................................... 35 
13.6 
Notification Reporting ............................................................................................... 36 
14 Sponsor Obligations ........................................................................................................ 36 
14.1 
Investigator(s) Training ............................................................................................. 36 
14.2 
Sponsor Study Termination........................................................................................ 36 
14.3 
Study Monitoring and Frequency of Monitoring Visits .............................................. 37 
15 Informed Consent ............................................................................................................ 37 
List of Appendices ................................................................................................................... 38 
Appendix A: Visit Schedule .................................................................................................. 39 
Appendix B: Patient Questionnaires ...................................................................................... 40 
Bibliography ...............................................................................................................................  

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 5 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Protocol Summary Page 
Title: 
A Prospective, Multi-center, Randomized Study Comparing the Superion® 
Interspinous Spacer (ISS) to the X-STOP® Interspinous Process 
Decompression (IPD®) System in Patients with Moderate Lumbar Spinal 
Stenosis – Continued Follow-Up 
Protocol Number: 
08-VISS-01, 19 June 2015 
Short Title: 
SPACER Trial – Superion® Post-Approval Clinical Evaluation and Review 
Study Treatment: 
Superion® Interspinous Spacer (“Superion® ISS”) 
Control Treatment 
Surgical implantation of the X-STOP® Interspinous Process Decompression 
(IPD®) System (“X-STOP® IPD®”) 
Study Design: 
Prospective, multi-center, randomized, controlled study 
Study Purpose: 
To demonstrate that the success rate of the study group receiving the 
Superion® Interspinous Spacer is not inferior to the success rate observed in 
the X-STOP® IPD® Control group, and that the Superion® Interspinous 
Spacer is safe when used in the treatment of moderately impaired lumbar 
spinal stenosis (LSS) patients, at 5 years post-surgery. 
Study Population: 
Subjects suffering from moderate symptoms of neurogenic claudication 
secondary to a confirmed diagnosis of moderate LSS at one or two 
contiguous levels from L1 to L5 who meet all inclusion/exclusion criteria. 
Number of Subjects: 
Up to 470 patients were enrolled in the clinical trial as follows: 
Randomized Trial: 
• 
An adaptively selected sample size - range 250-350 subjects  
• 
1:1 Randomization   
• 
A minimum of 125 to a maximum of 175 in each group.  
Non-randomized Trial: 
Prior to initiating the randomized trial, clinical sites could enroll 0-2 non-
randomized patients up to a maximum of 70 Superion® ISS non-
randomized “training” cases. 
The numbers of patients in the final primary analysis set for effectiveness 
and safety included 190 patients randomized to Superion® and 201 patients 
randomized to the X-STOP® IPD® Control group.  Eight (8) Superion® 
patients and 12 X-STOP® IPD patients are from 2 sites that are not 
participating in the PAS. This reduces the analysis set to 182 and 189, 
respectively.  Additionally, 28 training cases were enrolled.   
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 6 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Study Hypotheses: 
The primary hypothesis of this extended follow-up post approval study is 
that performance of the Superion® ISS remains clinically non-inferior to X-
STOP® IPD® at 5 years post-surgery using the same non-inferiority margin 
as was used at 2-years.  The hypotheses to be tested may be symbolically 
described as follows: 
Ho: CCSSuperion – CCSX-STOP ≤ -0.10 (inferior) 
Ha: CCSSuperion – CCSX-STOP > -0.10 (not inferior) 
At 2-years, follow-up compliance was 97% and 95%, and the observed 
overall success rates were 51.9% (95/183) and 49.7% (93/187) for 
Superion® ISS and X-STOP® IPD®, respectively.  For the purpose of sample 
size analysis it was initially assumed: a) that at 5-years, follow-up 
compliance would be 85% in both groups (i.e., 155 Superion® and 161 X-
STOP® IPD®); b) a device group difference equal to that observed at 2-
years (i.e., 2.2%); and c) at 5-years 40% of Superion® ISS would achieve 
CCS (and so 37.8% is assumed for X-STOP® IPD®).  In keeping with the 
original design, these hypotheses will be tested by determining the 
Bayesian posterior probability that (CCSSuperion – CCSX-STOP)> -0.10.  If the 
Bayesian posterior probability is at least equal to 0.95, then the hypothesis 
that Superion® ISS is non-inferior to X-STOP® IPD® at 5-years will be 
accepted.  Non-informative beta(1,1) priors were assumed for both groups.  
With these assumptions, power is 73% and type 1 error is 0.05.  However, 
updated Month 36 results reflect a device group difference equal to 5.7%.  
Conservatively assuming a 5% difference, power increases to 87% and 
remains above 80% for device group differences larger than about 3.5%. 
The following superiority hypotheses will be tested if non-inferiority is 
demonstrated.  By the closed testing principle there is no need for 
multiplicity adjustment.  
Ho: CCSSuperion – CCSX-STOP ≤   0 (not superior) 
Ha: CCSSuperion – CCSX-STOP >   0 (superior) 
The posterior probability that (CCSSuperion – CCSX-STOP) > 0 will be 
determined using Beta(1,1) priors for 5-year e CCSSuperion and for 5-year 
CCSX-STOP.  If the posterior probability of superior is at least equal to 0.95, 
then a superiority claim will be made. 
Number of Sites: 
Only sites participating in the original IDE study will participate in this 
continued follow-up protocol.  25 IDE sites remain eligible for 
participation. 
Study Enrollment: 
Enrollment was completed in December 2011, with 391 randomized and 
treated patients and 28 non-randomized Superion® training patients. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 7 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Study Duration: 
Subjects included in the original clinical investigation (G070118) returned 
for follow-up visits at 6 weeks, and 3, 6, 12, 18 and 24 months post-
treatment to collect data for the primary evaluation of safety and 
effectiveness.  Patients will be followed annually until each patient has 
reached the 60 month time point.  Study duration is approximately 36 
months as all patients have reached 24 months prior to the start of this 
continued follow-up protocol.  Patients may potentially be followed 
annually for up to 10 years as part of a possible post-approval study. 
Inclusion Criteria 
1. Male or female subjects ≥ 45 years of age. 
2. Persistent leg/buttock/groin pain, with or without back pain, 
that is relieved by flexion activities (example: sitting or 
bending over a shopping cart) 
3. Subjects who have been symptomatic and undergoing 
conservative care treatment for at least 6 months. 
4. Diagnosis of degenerative spinal stenosis of the lumbar spine, 
defined as the narrowing of the midline sagittal spinal canal 
(central) and/or narrowing between the facet superior articulating 
process (SAP), the posterior vertebral margin (lateral recess), and 
the nerve root canal (foraminal).  
5. Radiographic confirmation of at least moderate spinal stenosis 
which narrows the central, lateral, or foraminal spinal canal at one 
or two contiguous levels from L1-L5. Moderate spinal stenosis is 
defined as 25% to 50% reduction in lateral/central foramen 
compared to the adjacent levels, with radiographic confirmation of 
any one of the following: 
o Evidence of thecal 
sac and/or cauda equina 
compression  
o Evidence of nerve root impingement (displacement or 
compression) by either osseous or non-osseous 
elements 
o Evidence 
of 
hypertrophic 
facets 
with 
canal 
encroachment  
6. Must present with moderately impaired Physical Function (PF) 
defined as a score of > 2.0 of the Zurich Claudication 
Questionnaire (ZCQ) 
7. Must be able to sit for 50 minutes without pain and to walk 50 feet 
or more  
8. Subjects who are able to give voluntary, written informed consent 
to participate in this clinical investigation and from whom consent 
has been obtained 
9. Subjects, who, in the opinion of the Clinical Investigator, are able 
to understand this clinical investigation, cooperate with the 
investigational procedures and are willing to return for all the 
required post-treatment follow-ups. 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 8 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Note:  In Criterion #5, all imaging used to confirm LSS need be completed 
within 3 months prior to enrollment.  Radiographic confirmation of LSS 
may include MRI and/or CT.  In the case of a transitional L5/L6 segment 
with a sufficiently prominent L6 spinous process, these could be included 
by requesting a deviation from the Sponsor. 
Exclusion Criteria 
1. Axial back pain only 
2. Fixed motor deficit 
3. Diagnosis of lumbar spinal stenosis which requires any direct 
neural decompression or surgical intervention other than those 
required to implant the control or investigational device 
4. Unremitting pain in any spinal position 
5. Significant peripheral neuropathy or acute denervation secondary 
to radiculopathy 
6. Lumbar spinal stenosis at more than two levels determined pre-
operatively to require surgical intervention 
7. Significant instability of the lumbar spine as defined by ≥ 3mm 
translation or  
≥ 5° angulation 
8. Sustained pathologic fractures of the vertebrae or multiple 
fractures of the vertebrae and/or hips 
9. Spondylolisthesis or degenerative spondylolisthesis greater than 
grade 1.0 (on a scale of 1-4) 
10. Spondylolysis (pars fracture) 
11. Degenerative lumbar scoliosis with a Cobb angle of > 10° at 
treatment level 
12. Osteopenia or osteoporosis.  To confirm eligibility, at the Clinical  
Investigator’s discretion, the following subjects may have a DEXA 
scan performed: 
-Women 65 or older 
-Postmenopausal women < age 65 
-Subjects with major risk factors for or diagnosed with 
osteoporosis or osteopenia 
If DEXA is required, exclusion is defined as a DEXA bone density 
measurement T score ≤ -2.5  
13. Morbid obesity, defined as Body Mass Index (BMI) greater than 
40kg/m2 
14. Insulin-dependent diabetes mellitus 
15. Significant peripheral vascular disease (diminished dorsalis pedis 
or tibial pulses) 
16. Prior surgery of the lumbar spine  
17. Cauda equina syndrome (defined as neural compression causing 
neurogenic bowel or bladder dysfunction) 
18. Infection in the disc or spine, past or present 
19. Evidence of active (systemic or local) infection at time of surgery  
20. Active systemic disease such as AIDS, HIV, hepatitis, etc. 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 9 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
21. Paget’s disease at involved segment or metastasis to the vertebra, 
osteomalacia, or other metabolic bone disease 
22. Currently undergoing immunosuppressive therapy or long-term 
steroid use 
23. Known allergy to titanium or titanium alloys 
24. Tumor in the spine or a malignant tumor except for basal cell 
carcinoma 
25. Known or suspected history of alcohol and/or drug abuse  
26. Prisoner or transient 
27. Life expectancy less than two years 
28. Angina, active rheumatoid arthritis, or any other systemic disease 
that would affect the subject’s welfare or outcome of the clinical 
investigation 
29. Any significant psychological disturbance past or present, 
psychotic or neurotic that could impair the consent process or 
ability to complete subject self-report questionnaires 
30. Involved in pending litigation of the spine or worker’s 
compensation related to the back 
31. Enrolled in the treatment phase of another drug or device clinical 
investigation (currently or within past 30 days) 
32. Congenital defect of the spine 
33. Pregnant or lactating 
Composite Endpoint 
(Primary) - 
Individual Patient  
Success: 
An individual subject will be considered a success if they meet all of the 
following conditions at the 60 month follow-up visit: 
• Clinically significant improvement in outcomes compared to baseline, 
as determined by meeting the following for at least two of three 
domains of the Zurich Claudication Questionnaire (ZCQ): 
o Improvement in physical function by  ≥ 0.5 points 
o Improvement in symptom severity by  ≥ 0.5 points 
o “Satisfied” or “somewhat satisfied” as defined by a score 
of < 2.5 points on the patient satisfaction domain 
• No re-operations, revisions, removals or supplemental fixation at the 
index level(s) 
• No major implant or procedure-related complications defined as:  
o No dislodgement, migration, or deformation 
o No new or persistent worsened neurological deficit at the 
index level 
o No spinous process fractures 
o No deep infection, death, or other permanent device 
attributed disability  
• No clinically significant confounding treatments:  
o No epidural injections or nerve block procedures at index 
level, spinal cord stimulators or rhizotomies 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 10 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Secondary 
Endpoints: 
• To demonstrate the superiority of Superion® ISS to X-STOP® IPD® 
in effectively treating moderately impaired LSS patients as measured 
by 60 months postoperative overall success rates, using the same 
criteria as 24 months.  
• VertiFlex® Patient Satisfaction Survey:  percent of patients scoring     
≤ 2.5 on a 4 point scale  
• Oswestry Disability Index (ODI) Version 2: compared to baseline, 
15 point improvement (reduction in score) is considered clinically 
significant 
• Visual Analogue Scale (VAS): compared to baseline, an 
improvement in leg and/or back pain of 20 mm (on a 100 mm scale) 
is considered clinically significant  
• To evaluate generic health status pre- and postoperatively using the 
SF-12 Short Form Health Survey, Version 2  
• To evaluate maintenance of distraction defined by ≤ 4 mm of 
measurable decrease in the posterior disc space height on successive 
radiographs obtained at 6 weeks and 24 months postoperatively  
Safety Endpoints: 
Data will be evaluated for safety endpoints by an independent Clinical 
Events Committee (CEC). Safety outcomes will be determined by 
evaluating the type, frequency, severity, and relationship to device of 
adverse events through the 60-month time point for all subjects.  Adverse 
events will be categorized as implant-related or procedure-related.  All 
device-related and major procedure-related failures reported by the site PIs 
will be adjudicated by the independent CEC.  In addition, events reported 
as having unknown or undetermined relationship to the device by the PI 
will be adjudicated by the CEC. 
Other Endpoints: 
• 
Work status and time to return to work or normal (pre-operative) 
activities of daily living (ADL) 
• 
Narcotic use 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 11 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Principal Study Contacts
 
Sponsor/Medical Monitor 
 
VertiFlex®, Inc. 
1351 Calle Avanzado, Suite 100 
San Clemente, CA 92673 
EMAIL: clinical@vertiflex.net 
TEL: (949) 940 1400 
FAX: (949) 940 1475 
 
 
Radiographic Core Lab  
 
Medical Metrics, Inc. 
2121 Sage Road, Suite 300 
Houston, TX 77056 
TEL: (713) 850 7500 
FAX: (713) 850 9996

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 12 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
1 
Introduction and Background 
1.1 Introduction 
Lumbar Spinal Stenosis (LSS) is characterized as a narrowing of the spinal canal and/or the 
intervertebral foramina that decreases space for the neural elements in the lumbar region of the 
spine.1,2,3,4,5,6  As early as the 1950’s it was recognized by Verbiest7 that structural narrowing of 
the vertebral canal could compress the cauda equina and produce neurogenic claudication 
symptoms.  These include leg pain (and occasionally weakness, numbness, or cramping) on 
walking or standing, which is relieved by sitting or spinal flexion. 
 
Increasing numbers of people in the aging population that suffer from LSS symptoms have 
commanded the attention of both medical practitioners and industry representatives.8,9  As such, 
there have been great strides to identify the least invasive treatment for patients with LSS that 
would successfully enhance their function and mobility, thus leading to improved, if not a restored 
quality of life.10,11,12,13,14 
 
Nonsurgical management (NSM), or conservative care, is well-established as the first-line 
treatment approach for LSS patients with mild to moderate symptoms.15,16,17,18,19,20  NSM typically 
involves the prescription of bed rest or controlled physical activity, physiotherapy, anti-
inflammatory drugs, epidural steroid injections, the use of a lumbar corset, or some combination 
thereof.23  While some patients are able to obtain relief from symptoms with these measures, many 
others do not obtain adequate relief over the long-term.  
 
Surgical treatment, i.e. laminectomy with or without fusion, is generally accepted as the standard 
of care for LSS patients with severe symptoms.21,22,23,24,25,26   LSS is currently the most common 
diagnosis for patients 55 years or older scheduled for spinal surgery.27,28,29,30  This dramatic 
increase in the number of surgeries is attributable to improved diagnostic imaging techniques, 
improved and less invasive surgical techniques, the aging population, and improved patient 
education.31,32,33,34,35  This is elective surgery to improve the quality of life for these individuals 
who have disabling back and leg pain and significant limitations in walking tolerance.36,37,38  
Cauda equina syndrome is the only absolute indication for decompressive laminectomy.39 
 
The treatment algorithm for patients with moderate LSS symptoms is less well-defined.  Clinical 
symptoms combined with radiographic findings should determine the optimal care for this group 
of patients.  These patients may obtain partial relief from NSM measures but remain dissatisfied 
with their outcomes, or they may have failed an extended course of NSM but are unable or 
unwilling to undergo major surgery. Until recently, there were no other treatment options available 
for this patient population.  With the first commercial introduction of interspinous spacers into the 
US marketplace in 2005 (X-STOP® IPD®, Medtronic, Inc., Minneapolis, MN), a new, less invasive 
treatment alterative became available for this patient population.  Subsequently, the Superion® 
Interspinous Spacer (Superion® ISS) was granted FDA approval to market in the U.S. on May 20, 
2015, pursuant to PMA No. P140004, and following conduct of a clinical trial randomized against 
the X-STOP® IPD® device conducted under IDE #G010118.  This trial is intended to acquire 60 
month follow-up of subjects enrolled in that IDE study. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 13 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
The Superion® Interspinous Spacer is a new minimally invasive spinal implant that limits 
extension at the symptomatic level designed for percutaneous surgical techniques.  The device is 
intended to treat moderate spinal stenosis in the adult spine and can be implanted under general 
anesthesia or local anesthesia with or without conscious sedation.  Following sequential dilation, 
the Superion® ISS is implanted via a small dilation or incision through the supraspinous ligament.  
The device presents little or no risk to nervous and vascular structures.  If necessary, the Superion® 
ISS can be easily removed through the same portal using percutaneous or minimally invasive 
techniques with very little alteration to the lumbar spinal anatomy. 
 
This Conditions of Approval clinical trial is designed to evaluate the safety and effectiveness of 
the Superion® ISS through 60 months post-treatment, compared to the X-STOP® IPD®, in healthy 
adults suffering moderate spinal stenosis symptoms who have been unresponsive to at least 6 
months of conservative, or non-surgical care. 
1.2 
Rationale for this Investigation 
Interspinous spacers offer an alternative option in the treatment of adult patients with symptomatic 
moderate LSS.  At the present time, the X-STOP® IPD® and the Superion® ISS are the only 
interspinous spacers commercially available to this patient population within the United States. 
 
The Superion® ISS device is an interspinous spacer intended for use in the treatment of moderate 
LSS patients and is designed to limit extension at the symptomatic level, open up the spinal canal 
and foraminal areas, and relieve pressure on the nerve roots.  The X-STOP® IPD® interspinous 
spacer was selected as the active control treatment because of its similarities to the Superion® ISS 
with respect to device design, intended patient population, indications for use, degree of 
invasiveness, risk profile, and anticipated clinical outcomes. 
The STOP® IPD® IDE clinical study was conducted on a population of patients with mild to 
moderate LSS symptoms.  Results from this pivotal study have shown that patients who undergo 
X-STOP® IPD® implantation have superior clinical outcomes when compared to patients who 
undergo non-surgical management.40  Further analysis of the main study findings by that study’s 
sponsor demonstrated that the subset of X-STOP® IPD® patients with moderately impaired 
physical function at baseline (defined as a Physical Function [PF] domain score > 2.0 using the 
Zurich Claudication Questionnaire [ZCQ]) was the patient population most likely to benefit from 
the device41.  As a result, the X-STOP® IPD® indications for use were modified at the time of PMA 
approval to include only those LSS patients with moderate physical function impairment at 
baseline.  
 
Based on the results of the X-STOP® IPD® clinical trial and the X-STOP® IPD® PMA approval 
order, LSS patients with moderate physical function impairment at baseline comprised the patient 
population eligible for enrollment into the Superion® ISS clinical trial.  Therefore, this IDE study 
was a prospective, controlled, randomized study comparing the Superion® ISS with X-STOP® 
IPD® in patients with moderate physical function impairment due to LSS. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 14 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
The primary endpoint of this PAS trial is Month 60 composite clinical success (CCS).  The primary 
effectiveness hypothesis for the PAS is that Superion® ISS is clinically non-inferior to X-STOP® 
IPD® (non-inferiority margin = -0.10) at Month 60.  The Superion® ISS provides a minimally 
invasive technique, and is a single-piece design to minimize the potential for breakage or 
disassembly.  Further, the minimally invasive technique allows the device to be delivered with 
minimum disruption to the soft tissue, potentially minimizing the risk of migration.  Thus, although 
the study is designed to demonstrate non-inferiority, there are several potential advantages of the 
Superion® ISS that will be evaluated based on the results of the investigation at the conclusion of 
the 60 month follow-up. 
2 
Device Name 
The Superion® Interspinous Spacer (ISS) 
3 
Intended Use of the Device 
The Superion® InterSpinous Spacer (ISS) is indicated to treat skeletally mature patients suffering 
from pain, numbness, and/or cramping in the legs (neurogenic intermittent claudication) secondary 
to a diagnosis of moderate degenerative lumbar spinal stenosis, with or without Grade 1 
spondylolisthesis, confirmed by X-ray, MRI and/or CT evidence of thickened ligamentum flavum, 
narrowed lateral recess, and/or central canal or foraminal narrowing.  The Superion® ISS is 
indicated for those patients with moderately impaired physical function who experience relief in 
flexion from symptoms of leg/buttock/groin pain, numbness, and/or cramping, with or without 
back pain, and who have undergone at least 6 months of non-operative treatment.  The Superion® 
ISS may be implanted at one or two adjacent lumbar levels in patients in whom treatment is 
indicated at no more than two levels, from L1 to L5. 
 
For this intended use, moderate degenerative lumbar spinal stenosis was defined as follows: 
• 25% to 50% reduction in the central canal and/or nerve root canal (subarticular, 
neuroforaminal) compared to the adjacent levels on radiographic studies, with radiographic 
confirmation of any one of the following: 
o Evidence of thecal sac and/or cauda equina compression 
o Evidence of nerve root impingement (displacement or compression) by either osseous or 
non-osseous elements 
o Evidence of hypertrophic facets with canal encroachment 
• AND associated with the following clinical signs: 
o Presents with moderately impaired Physical Function (PF) defined as a score of ≥ 2.0 of 
the Zurich Claudication Questionnaire (ZCQ) 
o Ability to sit for 50 minutes without pain and to walk 50 feet or more. 
4 
Device Description 
4.1 
Superion® Interspinous Spacer (ISS) – Study Device 
The Superion® Interspinous Spacer (ISS) device is a non-fusion, spinal column load-sharing device 
used to stabilize the spine at the implanted level.  When implanted between contiguous spinous 
processes, it is designed to provide distraction at the affected spinal level and reduce compression 
of neural elements in extension. 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 15 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
The Superion® ISS may be implanted under general or local anesthesia.  With the spine positioned 
in flexed position, the Superion® ISS is inserted between adjacent vertebral spinous processes at 
one level, or at two contiguous levels.  The degree of flexion to relieve the stenotic condition is 
determined by the operating surgeon using fluoroscopy.  Figure 1 illustrates the Superion® ISS 
device in situ after implantation, with the superior and inferior cam lobes engaging the lateral 
aspects of L3 and L4 spinous processes: 
Figure 1:  Superion® ISS Implant in situ 
 
 
 
A/P View 
 
Lateral View 
Five (5) sizes of the Superion® ISS device are available (8mm, 10mm, 12mm, 14mm, and 16mm).  
Implant “size” refers to the distance between the cam lobes, which corresponds to the amount of 
distraction the implant will provide when it is implanted between two spinous processes. 
 
The Superion® ISS implant is composed entirely of titanium 6Al-4V ELI alloy conforming to 
ASTM Standard F136 (2002), Standard Specification for Wrought Titanium-6 Aluminum-4 
Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications.  This material is 
widely used in spinal and other orthopedic implants, and is recognized as a safe, biocompatible 
material after decades of use in implantable devices of many types.  Manual instruments provided 
for use with the Superion® ISS implant are composed of durable materials traditionally employed 
to manufacture surgical instrumentation, and which are known to tolerate repeated cleaning, 
sterilization, and use.  The materials include various grades of stainless steel (e.g., 300 and 400 
series, 17-4 PH), aluminum, and titanium and/or polymers (RADEL) all of which conform to 
applicable ASTM material specifications. 
The Superion® ISS implant is provided in assembled form, and is supplied sterile and intended for 
single-use only. Manual instruments are provided non-sterile, and are intended to be sterilized by 
the user before use. Complete instructions for use of the instrumentation are contained in the 
Superion® ISS Surgical Technique Manual. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 16 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
4.2 
X-STOP® Interspinous Decompression (IPD®) System – Control Treatment 
The X-STOP® IPD® is an FDA-approved implant for the treatment of patients aged 50 years or 
older suffering from moderate symptoms of neurogenic intermittent claudication secondary to a 
confirmed diagnosis of LSS.  The X-STOP® IPD® implant is a titanium metal implant designed to 
fit between the spinous processes in the lumbar spine.  For additional information, please refer to 
the X-STOP® IPD® surgical technique supplied by the manufacturer with the device. 
5 
Study Overview 
5.1 
Purpose 
The purpose of this study is to demonstrate that the success rate of the Study group receiving the 
Superion® Interspinous Spacer is not inferior to the success rate observed in the X-STOP® IPD® 
control group at 60 months follow-up, and that the Superion® Interspinous Spacer is safe when 
used in the treatment of moderately impaired LSS patients.  This safety and effectiveness data will 
be used to satisfy the Agency-imposed Conditions of Approval of the Superion® Premarket 
Approval (PMA). 
5.2 
Study Endpoints 
5.2.1 Composite Endpoint (Primary) – Individual Patient Success 
Subjects will be evaluated for success at each follow-up interval through 60 months.  The primary 
study endpoint is the rate of overall subject success at the 60 month follow-up visit. An individual 
subject will be considered a success if they meet all of the following conditions at the 60 month 
follow-up: 
 
Clinically significant improvement in outcomes compared to baseline, as determined by meeting 
the following: 
 
• At least two of three domains of the Zurich Claudication Questionnaire (ZCQ) 
o Improvement in physical function by ≥0.5 points 
o Improvement in symptom severity by ≥0.5 points 
o “Satisfied” or “somewhat satisfied” as defined by a score of ≤ 2.5 points on the 
patient satisfaction domain 
• No re-operations, revisions, removals or supplemental fixation at the index level(s) 
• No major implant- or procedure-related complications: 
o No dislodgement, migration, or deformation 
o No new or persistent worsened neurological deficit at the index level 
o No spinous process fractures 
o No deep infection, death, or other permanent device attributed disability 
• No clinically significant confounding treatments: 
o No epidural injections or nerve block procedures at index level, spinal cord 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 17 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
5.2.2 Secondary Endpoints 
The secondary endpoints of this investigation are: 
• To demonstrate the superiority of Superion® ISS to X-STOP® IPD® in effectively treating 
moderately impaired LSS patients as measured by 60 months postoperative overall success 
rates 
• VertiFlex® Patient Satisfaction Survey – percent of patients scoring ≤ 2.5 on a 4 point scale 
• Oswestry Disability Index (ODI) Version 2– compared to baseline, 15 point improvement 
(reduction in score) is considered clinically significant 
• Visual Analogue Scale (VAS) - compared to baseline, an improvement in leg and/or back 
pain of 20 mm (on a 100 mm scale) is considered clinically significant  
• To evaluate generic health status pre- and postoperatively using the SF-12 Short Form Health 
Survey, Version 2  
• To evaluate maintenance of distraction defined by ≤ 4 mm of measurable decrease in the 
posterior disc space height on successive radiographs obtained at 6 weeks and 60 months 
postoperatively  
5.2.3 Safety Endpoints and Role of CEC 
Data will be evaluated for safety endpoints by an independent Clinical Events Committee (CEC).  
Safety outcomes will be determined by evaluating the type, frequency, severity, and relationship 
to device of adverse events through the 60-month time point for all subjects.  Adverse events will 
be categorized as implant-related or procedure-related.  All device-related events and major 
procedure-related failures reported by the site PIs will be adjudicated by the independent CEC.  In 
addition, events reported as having unknown or undetermined relationship to the device by the site 
PI will be adjudicated by the CEC. 
5.2.4 Other Endpoints 
• Work status and time to return to work or normal activities of daily living (ADL) 
• Narcotic use 
5.3 
Study Hypothesis 
The primary hypothesis of this extended follow-up post approval study is that performance of the 
Superion® ISS remains clinically non-inferior to X-STOP® IPD® at 5 years post-surgery using the 
same non-inferiority margin as was used at 2-years. The hypotheses to be tested may be 
symbolically described as follows: 
Ho: CCSSuperion – CCSX-STOP ≤ -0.10 (inferior) 
Ha: CCSSuperion – CCSX-STOP > -0.10 (not inferior) 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 18 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
At 2-years, follow-up compliance was 97% and 95%, and the observed overall success rates were 
51.9% (95/183) and 49.7% (93/187) for Superion® ISS and X-STOP® IPD®, respectively.  For the 
purpose of sample size analysis it was initially assumed: a) that at 5-years, follow-up compliance 
would be 85% in both groups (i.e., 155 Superion® and 161 X-STOP® IPD®); b) a device group 
difference equal to that observed at 2-years (i.e., 2.2%); and c) at 5-years 40% of Superion® ISS 
would achieve CCS (and so 37.8% is assumed for X-STOP® IPD®).  In keeping with the original 
design, these hypotheses will be tested by determining the Bayesian posterior probability that 
(CCSSuperion – CCSX-STOP)> -0.10.  If the Bayesian posterior probability is at least equal to 0.95, 
then the hypothesis that Superion® ISS is non-inferior to X-STOP® IPD® at 5-years will be 
accepted.  Non-informative beta(1,1) priors were assumed for both groups.  With these 
assumptions, power is 73% and type 1 error is approximately 0.05.  However, updated Month 36 
results reflect a device group difference equal to 5.7%.  Conservatively assuming a 5% difference, 
power increases to 87% and remains above 80% for device group differences larger than 3.5%. 
 
The following superiority hypotheses will be tested if non-inferiority is demonstrated.  By the 
closed testing principle there is no need for multiplicity adjustment.  
Ho: CCSSuperion – CCSX-STOP ≤   0 (not superior) 
Ha: CCSSuperion – CCSX-STOP >   0 (superior) 
The posterior probability that (CCSSuperion – CCSX-STOP) > 0 will be determined using Beta(1,1) 
priors for 5-year e CCSSuperion and for 5-year CCSX-STOP   If the posterior probability of superior 
is at least equal to 0.95, then a superiority claim will be made. 
5.4 
Duration and Extent of Investigation 
Subjects included in the clinical investigation have returned for follow-up visits at 6 weeks (± 2 
weeks), 3 months (± 2 weeks), 6 months (± 1 month), 12 months (± 2 months), 18 months (± 2 
months) and 24 months (± 2 months) post-treatment to collect data for the primary evaluation of 
safety and effectiveness.  Patients will continue to be followed annually (± 3 months) until each 
patient has reached the 60 month time point.  Study duration is anticipated to be extended by 
approximately 36 months to accommodate this additional follow-up. 
6   
Study Design 
This study is a prospective, multi-center, randomized controlled clinical trial comparing the 
Superion® ISS to the X-STOP® IPD® in the treatment of subjects aged 45 or older suffering from 
moderate symptoms of neurogenic intermittent claudication secondary to a confirmed diagnosis 
of moderate LSS at one or two contiguous levels from L1 to L5, i.e. from the L1-L2 level to the 
L4-L5 level.  Implantation of the X-STOP® IPD® for patients aged 45-49 years is considered 
investigational.  A maximum of 35 investigative sites in the U.S. enrolled subjects into the trial 
using a 1:1 randomization assignment and an adaptively selected sample size ranging from 250 to 
350 subjects (125-175 enrolled into each group). 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 19 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Up to an additional 50 patients (25 per group) were allowed to be enrolled to allow for loss to 
follow-up.  In addition, prior to initiating the randomized trial, clinical sites were permitted to 
enroll 0-2 non-randomized “training” patients to receive the Superion® ISS.  A total of 470 subjects 
were enrolled into the study.  An investigative site is defined as a facility or facilities in the same 
general geographic location if they are under the control of a local Institutional Review Board 
(IRB).  A total of 33 sites were authorized to enroll subjects.  Two (2) failed to enroll any subjects 
and were discontinued from the trial.  Of the remaining 31 sites that enrolled one or more subjects, 
six (6) have since discontinued participation, leaving 25 sites actively participating in the extended 
follow-up described by this protocol. 
 
The numbers of patients in the final primary analysis set for effectiveness and safety included 190 
patients randomized to Superion® and 201 patients randomized to the X-STOP® IPD® Control 
group.  Eight (8) Superion® patients and 12 X-STOP® IPD patients are from 2 sites that are not 
participating in the PAS. This reduces the analysis set to 182 Superion® and 189 X-STOP® IPD®, 
respectively.  Assuming 85% follow-up for the primary effectiveness endpoint at Month 60, there 
will be 155 Superion® patients and 161 X-STOP® IPD patients included in the primary non-
inferiority evaluation.  
 
After implantation of the Superion® ISS or the X-STOP® IPD® device, each Investigator provided 
a postoperative care regimen based on the subject’s specific need.  The regimen may have 
included, but was not limited to:  medications, a corset or brace, acupuncture, traction, physical 
therapy, chiropractic treatment, use of a TENS unit and massage therapy.  The type and amount of 
the postoperative care were collected. 
 
At each follow-up visit through 60 months, subjects will be interviewed to determine if they have 
experienced adverse events (AEs) since the previous follow-up visit.  A neurological assessment 
will be performed for all patients at baseline and all follow-up visits.  All subjects will be required 
to complete ZCQ, ODI, VAS, SF-12, and the VertiFlex® Patient Satisfaction questionnaires to 
evaluate disability, function, pain, quality of life and satisfaction at each follow-up visit.  Subjects 
were also required to complete a VAS questionnaire to evaluate pain status at discharge.  
 
The potential impact of spinal injections/nerve blocks use on the ZCQ was evaluated based on 
review of the medical literature.1  As these are potentially confounding of the ZCQ outcomes, 
epidural steroid injections or nerve block procedures at the treated level(s) will be deemed failures.  
Further, rhizotomy procedures at the treated level(s) will be deemed failures. 
 
 
                                               
1 Campbell's Operative Orthopedics (11th ed.) at 2281:  "Although epidural steroid injections have been 
used in the treatment of spinal stenosis for many years, no scientifically validated long-term outcomes have 
been reported to substantiate their use, and most prospective reports show no statistically significant benefit.  
A meta-analysis showed that epidural steroids have little short-term advantage over placebo for treatment 
of leg pain."  See also Carette S, Marcoux S, Truchon R, Grondin C, Gagnon J, Allard Y, Latulippe M.  
(1991) A controlled trial of corticosteroid injections into facet joints for chronic low back pain.  NEJM 
325(14):1002-1007. Jackson RP, Jacobs RR, Montesano PX (1988).  Facet joint injection in low-back pain: 
A prospective statistical study.  Spine 13(9):966-71. 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 20 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
With respect to spinal cord stimulators, because the use of a permanent implant would require a 
surgical procedure, this will be deemed a study failure. 
 
Radiographic evaluations were performed at discharge, and at each scheduled follow-up visit and 
prior to any re-operations.  The Investigator may obtain x-rays at unscheduled visits or to assess 
adverse events, if clinically indicated. 
6.1 
Study Population and Source of Subjects 
The study population consists of male and female subjects who are equal to or older than 45 years 
of age at time of enrollment, with moderate symptoms of neurogenic intermittent claudication and 
a confirmed diagnosis of moderate lumbar stenosis at one or two contiguous levels from L1 to L5, 
i.e level L1-L2 through level L4-L5, who met all inclusion/exclusion criteria and remain in follow-
up from the original IDE study. 
6.2 
Randomization 
A computer-generated random list of treatment assignments (Master Randomization List) was 
created using a 1:1 ratio.  Randomization occurred as close to the beginning of the treatment 
procedure as possible.  Due to differences in the procedures, incision sizes, and operative 
positioning, subjects were not masked to their treatment arm after the surgery, but were not advised 
by site staff of their treatment assignment. 
 
Sites used a web-based system to obtain treatment randomization assignment.  The clinical sites 
were provided with system usage instructions, usernames, passwords, and technical support 
contact information.  Randomization assignments were not re-used in the event that a subject 
withdrew from the study prior to surgery or became a study treatment failure.   
6.3 
Subject Eligibility Criteria 
The Principal or Sub-Investigator (PI or Sub-I) at each site was responsible for verifying that a 
potential study subject met all eligibility criteria and had none of the exclusion criteria.  All patients 
who satisfied the inclusion and exclusion criteria and sign the Informed Consent were eligible to 
proceed to randomization and enrollment.  
6.3.1 Inclusion Criteria 
Candidates for this study met ALL of the following criteria: 
34. Male or female subjects ≥ 45 years of age. 
35. Persistent leg/buttock/groin pain, with or without back pain, that is relieved by flexion 
activities (example: sitting or bending over a shopping cart) 
36. Subjects who have been symptomatic and undergoing conservative care treatment for at 
least 6 months. 
37. Diagnosis of degenerative spinal stenosis of the lumbar spine, defined as the narrowing of the 
midline sagittal spinal canal (central) and/or narrowing between the facet superior articulating 
process (SAP), the posterior vertebral margin (lateral recess), and the nerve root canal 
(foraminal).  
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 21 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
38. Radiographic confirmation of at least moderate spinal stenosis which narrows the central, 
lateral, or foraminal spinal canal at one or two contiguous levels from L1-L5. Moderate spinal 
stenosis is defined as 25% to 50% reduction in lateral/central foramen compared to the adjacent 
levels, with radiographic confirmation of any one of the following: 
o Evidence of thecal sac and/or cauda equina compression  
o Evidence of nerve root impingement (displacement or compression) by either 
osseous or non-osseous elements 
o Evidence of hypertrophic facets with canal encroachment  
39. Must present with moderately impaired Physical Function (PF) defined as a score of > 2.0 of 
the Zurich Claudication Questionnaire (ZCQ) 
40. Must be able to sit for 50 minutes without pain and to walk 50 feet or more  
41. Subjects who are able to give voluntary, written informed consent to participate in this clinical 
investigation and from whom consent has been obtained 
42. Subjects, who, in the opinion of the Clinical Investigator, are able to understand this clinical 
investigation, cooperate with the investigational procedures and are willing to return for all the 
required post-treatment follow-ups. 
Note:  In Criterion #5, all imaging used to confirm LSS need be completed within 3 months prior to 
enrollment.  Radiographic confirmation of LSS may include MRI and/or CT.  In the case of a transitional 
L5/L6 segment with a sufficiently prominent L6 spinous process, these could be included by requesting a 
deviation from the Sponsor. 
6.3.2 Exclusion Criteria 
Candidates were excluded from the study if ANY of the following applied: 
8. Axial back pain only 
9. Fixed motor deficit 
10. Diagnosis of lumbar spinal stenosis which requires any direct neural decompression or surgical 
intervention other than those required to implant the control or investigational device 
11. Unremitting pain in any spinal position 
12. Significant peripheral neuropathy or acute denervation secondary to radiculopathy 
13. Lumbar spinal stenosis at more than two levels determined pre-operatively to require surgical 
intervention 
14. Significant instability of the lumbar spine as defined by ≥ 3mm translation or ≥ 5° 
angulation 
8. Sustained pathologic fractures of the vertebrae or multiple fractures of the vertebrae and/or 
hips 
9. Spondylolisthesis or degenerative spondylolisthesis greater than grade 1.0 (on a scale of 1-4) 
43. Spondylolysis (pars fracture) 
44. Degenerative lumbar scoliosis with a Cobb angle of > 10° at treatment level 
45. Osteopenia or osteoporosis.  To confirm eligibility, at the Clinical Investigator’s discretion, the 
following subjects may have a DEXA scan performed: 
-Women 65 or older 
-Postmenopausal women < age 65 
-Subjects with major risk factors for or diagnosed with osteoporosis or osteopenia 
If DEXA is required, exclusion is defined as DEXA bone density measurement T score ≤ -2.5 
46. Morbid obesity, defined as Body Mass Index (BMI) greater than 40kg/m2 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 22 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
47. Insulin-dependent diabetes mellitus 
48. Significant peripheral vascular disease (diminished dorsalis pedis or tibial pulses) 
49. Prior surgery of the lumbar spine  
50. Cauda equina syndrome (defined as neural compression causing neurogenic bowel or 
bladder dysfunction) 
51. Infection in the disc or spine, past or present 
52. Evidence of active (systemic or local) infection at time of surgery  
53. Active systemic disease such as AIDS, HIV, hepatitis, etc. 
54. Paget’s disease at involved segment or metastasis to the vertebra, osteomalacia, or other 
metabolic bone disease 
55. Currently undergoing immunosuppressive therapy or long-term steroid use 
56. Known allergy to titanium or titanium alloys 
57. Tumor in the spine or a malignant tumor except for basal cell carcinoma 
58. Known or suspected history of alcohol and/or drug abuse  
59. Prisoner or transient 
60. Life expectancy less than two years 
61. Angina, active rheumatoid arthritis, or any other systemic disease that would affect the 
subject’s welfare or outcome of the clinical investigation 
62. Any significant psychological disturbance past or present, psychotic or neurotic that could 
impair the consent process or ability to complete subject self-report questionnaires 
63. Involved in pending litigation of the spine or worker’s compensation related to the back 
64. Enrolled in the treatment phase of another drug or device clinical investigation (currently or 
within past 30 days) 
65. Congenital defect of the spine 
66. Pregnant or lactating 
6.4 
Study Enrollment 
Each site evaluated consecutive spine patients for potential eligibility for study participation based 
on their age and medical symptoms.  Patients could be prescreened and preliminarily excluded 
because of failure to meet basic inclusion or exclusion criteria.  The Investigator could have 
approached patients who were considered be suitable for entry into this study. 
Patients were only considered evaluable after informed consent was obtained, eligibility for study 
entry had been verified by the Principal Investigator (PI) or designee at each site, randomization 
assignment had been provided, and treatment anesthesia administration had begun.  Patients that 
were randomized, and had an anesthesia start time recorded, but were not treated with the control 
device or the investigational device due to unforeseen circumstances were considered in the Intent to 
Treat protocol analysis as a failure in his or her randomized treatment group.  Patients that were 
randomized, but did not have a treatment administered, or an anesthesia start time recorded, were 
exited from the trial, and the reason for their screen failure was recorded and tallied.  
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 23 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
6.5 
Study Procedures 
6.5.1 Screening 
All potential subjects were screened for eligibility and were listed on the Screening/Enrollment Log.  
The Screening/Enrollment Log documented the date of screening, the results of screening, and the 
primary reason for excluding the subject (e.g. subject does not satisfy enrollment exclusion criteria or 
subject declined). 
 
Eligible patients who agreed to participate in the study were required to sign an Informed Consent 
prior to undergoing any study-related screening procedures that were not standard of care.  If the 
patient did not meet all eligibility criteria after signing Informed Consent and undergoing additional 
evaluation, the patient was considered a "screen failure" and was not be entered into the study.  The 
reason for all screen failures was tabulated. 
6.5.2 Baseline Assessment 
The following baseline assessments were performed: 
Subject Self-Report Questionnaires will be administered: 
• Zurich Claudication Questionnaire (ZCQ) 
• Visual Analogue Scale (VAS)  
• SF-12 version 2 Health Related Quality of Life 
• Oswestry Disability Index (ODI) 
Demographic/History and Physical Assessment: 
• Date of birth, race, ethnicity 
• Gender, weight, height, and body mass index (BMI) 
• Work status  
• Nicotine use  
• Leg and back pain  
• Medical treatment  
• Previous surgeries, co-existing diseases, any disabilities and concomitant 
medication   
Neurological Assessment: 
• Muscle strength 
• Sensory and Reflexes 
• Range of motion 
• Palpation of pulses 
• Straight leg raise 
• Femoral Stretch 
Radiographic studies performed within 3 months of baseline: 
• Standing Anterior/Posterior Lumbar Spine view 
• Lateral Lumbar Spine view 
• Flexion/Extension Lateral Lumbar Spine views 
• MRI or CT Scan 
• DEXA Scan (If indicated) 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 24 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
6.5.3 Randomization and Enrollment 
Randomization assignment was conducted at the end of the baseline period.  After a patient had 
signed Informed Consent, and demonstrated eligibility based upon ALL inclusion/exclusion criteria, 
the patient was randomly assigned to a treatment group and surgery was scheduled.  The 
randomization occurred as close as possible to the date of the treatment procedure. 
Patients were only considered evaluable after Informed Consent had been obtained, eligibility for 
study entry had been verified by the Principal Investigator (PI) or designee at each site, 
randomization assignment had been provided, and treatment anesthesia administration had begun.  
Patients that were randomized, and had an anesthesia start time recorded, but were not treated with 
the control device or the investigational device due to unforeseen circumstances were considered in 
the Intent to Treat protocol analysis as a failure in his or her randomized treatment group.  Patients 
that were randomized, but did not have an anesthesia start time recorded, were exited from the trial 
and the reason for their screen failure was recorded and tallied.  
Treatment Procedures:  Investigational (Superion® ISS) and Control (X-STOP® IPD®) 
groups 
Surgical procedure: 
• Follow the applicable surgical procedure:  Superion® ISS Surgical Technique Manual 
or X-STOP® IPD® Surgical Technique Manual (Manufacturer’s Instructions) 
• Perform the procedure under fluoroscopic guidance 
• Surgery under local anesthesia with or without conscious sedation is recommended.  
General anesthesia is allowed at the discretion of the Investigator. 
 
The following information was collected at the time of surgery: 
• Date of admission 
• Date of surgery 
• Type of anesthesia 
• Level(s) treated 
• Device information 
• Operative time 
• Estimated blood loss 
• Intra-operative adverse events 
6.5.4 Post-Procedure Visits 
The following was collected at the Discharge Assessment for treated patients (0-7 days) 
 
Most patients were discharged the day of procedure.  If clinically indicated, some patients stayed 
for up to 23 hours or were admitted based on co-morbid conditions. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 25 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Discharge Assessment: 
• Visual Analogue Scale (VAS) to assess leg and back pain 
• Medical treatment  
• Adverse event 
• Concomitant medication and treatment 
• Length of hospital stay  
• Type of anesthesia 
Neurological Assessment: 
• Muscle strength 
• Sensory and Reflexes 
• Range of motion 
• Palpation of pulses 
• Straight leg raise 
• Femoral Stretch 
Radiographic studies: 
• Standing Anterior/Posterior Lumbar Spine X-ray 
• Lateral Lumbar Spine X-ray 
The following information was/will be collected at the Follow-up Visits for treated patients at 
 6-week (± 2 weeks), 3-month (± 2 weeks), 6-month (± 1 month), 12-month (± 2 months), 18-month 
(± 2 months), 24-month (± 2 months), and will be collected annually (± 3 months) thereafter through 
60 months as required by this protocol: 
Subject Self-Report Questionnaires: 
• Zurich Claudication Questionnaire (ZCQ) 
• Visual Analogue Scale (VAS) 
• SF-12 version 2 Health Related Quality of Life 
• Oswestry Disability Index (ODI) 
• VertiFlex Patient Satisfaction Questionnaire 
Neurological Assessment: 
• Muscle strength 
• Sensory and Reflexes 
• Range of motion 
• Palpation of pulses 
• Straight leg raise 
• Femoral Stretch 
Follow-up Assessment: 
• Work status and time to return to work or normal ADL (activities of daily 
living) 
• Leg and back pain  
• Medical treatment  
• Adverse event 
• Concomitant medication and treatment, including narcotic usage 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 26 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Radiographic studies :  
• Standing Anterior/Posterior Lumbar Spine X-ray 
• Lateral Lumbar Spine X-ray 
• Flexion/Extension Lateral Lumbar Spine X-rays 
 
The Study Visit Schedule (Appendix A) provides an overview of activities to be performed at 
each annual study visit through 60 months. 
7 
Termination of Subject Participation 
Subjects may voluntarily withdraw from the study at any time for any reason.  The Investigator(s) 
may elect to withdraw a subject from the study at any time due to lack of compliance or for any 
reason unrelated to the study treatment if such a decision is in the subject’s best medical interest.  
If a subject withdraws from the study, or is withdrawn by the Investigator(s), as much follow-up 
data as possible will be obtained, particularly regarding possible adverse events.  The primary 
reason for termination or discontinuation will be documented on the End of Study Case Report 
Form. 
 
If the Investigator(s) reports a subject to be lost to follow-up, the monitor will ensure that 
documentation is complete regarding the reason(s) this has occurred and will ensure that every 
attempt is made by the Investigator(s) to contact the subject or significant other persons associated 
with the subject to determine subject status.  Appropriate documentation will consist of at least 
two documented attempts at contact via telephone, followed by an attempt to contact via registered 
U.S. Mail. 
8 
Study Deviation 
A study deviation is defined as an event where the clinical investigator or site personnel did not 
conduct the study according to the Clinical Protocol or the Investigator Agreement.  Deviations 
will be classified as follows: 
 
Major Deviation:  Any deviation from patient inclusion and exclusion criteria or patient 
informed consent procedures. 
Minor Deviation:  Deviation from a protocol requirement, such as incomplete or missed 
patient evaluations, follow-up performed outside specified time windows, etc. 
 
Investigators will be required to obtain proper approval from the Sponsor before initiating major 
deviations from the Clinical Protocol, except where necessary to protect the life or physical well-
being of a subject in an emergency.  Such approval will be documented in writing and maintained 
in the study files.  Although prior approval is generally not expected for minor deviation, the event 
must still be reported. 
 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 27 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Deviations will be reported to the Sponsor regardless of whether medically justifiable, pre-
approved by the Sponsor, or taken to protect the subject in an emergency.  Subject-specific 
deviations will be reported on the Protocol Deviation CRF.  Non-subject-specific deviations, (e.g. 
unauthorized use of a study device outside the study) will be reported in writing.  Investigators 
will also adhere to procedures for reporting study deviations to their IRB in accordance with their 
specific IRB reporting policies and procedures. 
9.0 
Adverse Events 
9.1  
Definitions 
An Adverse Event (AE) is any undesired clinical response or complication experienced by a 
subject.  All operative and postoperative AEs, whether device-related or not, will be recorded on 
the AE Case Report Forms. 
 
The Investigator, on the basis of his or her clinical judgment and the following definitions, will 
determine the severity of the AE and the relationship to the device and/or procedure: 
• Not related: The AE is clearly not related 
• Unknown/Undetermined:   The AE is unknown or undetermined to be related  
• Related:    The AE is clearly related 
• Device related:  The AE is related to the study device or the control device 
• Procedure related:  The AE is related to the procedure to implant the study or 
control device 
 
The severity of an AE may be mild, moderate or severe.  Severity is determined by the Clinical 
Investigator, using the following definitions, and is not necessarily the subject’s interpretation: 
Mild 
The AE is transient or causes mild discomfort.  There usually is no 
intervention/therapy required and the AE does not interfere with the 
subject’s normal activities. 
Moderate 
The AE causes some limitation in activity and some assistance may be 
needed.  There is no or minimal medical intervention/therapy required. 
Severe 
The AE causes marked limitation in activity. The subject’s usual daily 
 
activity 
is 
interrupted. 
 
The 
subject 
may 
require 
medical 
 
intervention/therapy, hospitalization is possible. 
The term “severe” is used to describe intensity (severity) of a specific event.  An event itself may 
be of relatively minor medical significance (such as a severe headache).  This is not the same as 
“serious”, which is based on event outcomes or actions taken to prevent or treat an event and is 
usually associated with events that pose a threat to the patient’s life or functioning. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 28 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
The AE is regarded as a Serious Adverse Event (SAE) if the injury or illness: 
A) Results in death 
B) Is life-threatening, 
C) Results in or prolongs hospitalization 
D) Results in permanent impairment of a body function or permanent damage to a body 
structure, or 
E) Necessitates medical or surgical intervention to preclude permanent impairment of a body 
function or permanent damage to a body structure. 
 
A Serious Adverse Device Effect (SADE) is a device related adverse event that has resulted in 
any of the consequences characteristic of a serious adverse event or that might have led to any of 
these consequences if suitable action had not been taken or intervention had not been made. 
 
An Unanticipated Adverse Device Effect (UADE) is any serious adverse effect on health or 
safety, any life-threatening problem or death caused by, or associated with a device, if that effect, 
problem, or death was not previously identified in nature, severity, or degree of incidence in the 
Risks identified for the study or control device; or any other unanticipated serious problem 
associated with a device that relates to the rights, safety, or welfare of subjects. 
 
The Sponsor’s Clinical Research group must be notified of all Unanticipated Adverse Device 
Effects and Serious Adverse Device Effects within 24 hours at: 
 
VertiFlex®, Inc., Clinical Research 
1351 Calle Avanzado, Suite 100 
San Clemente, CA 92673 USA 
Tel:  (866) 355-4675 
Fax: (949) 940-1475 
clinical@vertiflex.net 
9.2 
Anticipated Adverse Events 
All AEs identified for the study or control device in Section 12 are considered ‘anticipated’. 
9.3 
Subsequent Surgical Interventions 
If the patient requires a subsequent surgical intervention at the index level(s), the Investigator 
should exit the patient from the study and document the reason on the End of Study CRF.  The 
patient should be followed until discharge from post-operative care or resolution of any adverse 
events up to a maximum of 30 days.  Subsequent surgical interventions are defined as: 
• A revision is a procedure that adjusts or in any way modifies or removes part of the original 
implant configuration, with or without replacement of a component.  A revision may also 
include adjusting the position of the original configuration. 
• A removal is a procedure where all of the original system configuration are removed with 
or without replacement. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 29 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
• A reoperation is any surgical procedure at the involved level(s) that does not include 
removal, modification, or addition of any components to the system. 
• A supplemental fixation is a procedure in which additional instrumentation not under study 
in the protocol is implanted (e.g., supplemental placement of a rod/screw system or a 
plate/screw system). 
9.4 
Device Explant and Retrieval 
In the event of a Superion® device removal, the device and the Investigator’s written explanation 
of the event will be sent to the Sponsor following instructions from the Sponsor.  The 
Investigator(s) will also be required to document the failure mode of the device and submit it to 
the Sponsor. 
10 
Statistical Considerations and Methodology 
10.1 
Clinical Trial Objective 
The objective of this trial is to show that the Superion® Interspinous Spacer is safe and non-inferior 
in efficacy compared to the X-STOP® IPD® device in patients with moderate lumbar spinal 
stenosis at 60 months post-treatment. 
10.2 
Primary Outcome 
The treatment arm (Superion® ISS) is compared to a control comprising surgical implantation of 
the X-STOP® IPD® device.  The primary efficacy analysis is a responder analysis at 60-months 
post-op where a subject is a responder if each of the following are satisfied: 
 
• Clinically significant improvement in outcomes compared to baseline, as determined by 
meeting the following for at least two of three domains of the Zurich Claudication 
Questionnaire (ZCQ): 
o Improvement in physical function by  ≥ 0.5 points 
o Improvement in symptom severity by  ≥ 0.5 points 
o “Satisfied” or “somewhat satisfied” as defined by a score of < 2.5 points on the 
patient satisfaction domain 
• No re-operations, revisions, removals or supplemental fixation at the index level(s) 
• No major implant or procedure-related complications defined as:  
o No dislodgement, migration, or deformation 
o No new or persistent worsened neurological deficit at the index level 
o No spinous process fractures 
o No deep infection, death, or other permanent device attributed disability  
• No clinically significant confounding treatments:  
o No epidural injections or nerve block procedures at index level, spinal cord 
stimulators or rhizotomies 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 30 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
10.3 
Randomization 
1:1 for treatment to control.  A randomized block design at each site was used. 
10.4 
Analysis Populations 
The study contains two treatment arms with patients receiving either the Superion® ISS or the X-
STOP® IPD® device.  The following subject groups or analysis populations will be used to 
complete the analysis of data:  
 
Modified Intent-to-treat patient population (mITT): The mITT patient population will include all 
patients randomized, and with an anesthesia start time recorded, where patients will be classified 
by the group in which they are randomized, regardless of the treatment received.  
 
Per protocol patient population (PP):  The PP patient population will include all subjects with 60-
month follow-up data and no major protocol deviations and subjects that failed before 60 months 
and subsequently did not complete 60 months. 
 
The primary efficacy analysis will be conducted on the mITT patient population.  Secondary 
efficacy analyses will be done on the PP population.  All safety data will be analyzed based on the 
mITT patient population. 
 
The numbers of patients in the mITT analysis set included 190 patients randomized to Superion® 
and 201 patients randomized to the X-STOP® IPD® Control group.  Eight (8) Superion® patients 
and 12 X-STOP® IPD patients are from 2 sites that are not participating in the PAS. This reduces 
the analysis set to 182 Superion® and 189 X-STOP® IPD®, respectively.  Assuming 85% follow-
up for the primary effectiveness endpoint at Month 60, there will be 155 Superion® patients and 
161 X-STOP® IPD patients included in the primary non-inferiority evaluation.  
10.5 
Primary Statistical Analysis 
The primary hypothesis of this extended follow-up post approval study is that performance of the 
Superion® ISS remains clinically non-inferior to X-STOP® IPD® at 5 years post-surgery using 
the same non-inferiority margin as was used at 2-years.  The hypotheses to be tested may be 
symbolically described as follows: 
Ho: CCSSuperion – CCSX-STOP ≤ -0.10 (inferior) 
Ha: CCSSuperion – CCSX-STOP > -0.10 (not inferior) 
At 2-years, follow-up compliance was 97% and 95%, and the observed overall success rates were 
51.9% (95/183) and 49.7% (93/187) for Superion® ISS and X-STOP® IPD®, respectively.  For the 
purpose of sample size analysis it was initially assumed: a) that at 5-years, follow-up compliance 
would be 85% in both groups (i.e., 155 Superion® and 161 X-STOP® IPD®); b) a device group 
difference equal to that observed at 2-years (i.e., 2.2%); and c) at 5-years 40% of Superion® ISS 
would achieve CCS (and so 37.8% is assumed for X-STOP® IPD®).  In keeping with the original 
design, these hypotheses will be tested by determining the Bayesian posterior probability that 
(CCSSuperion – CCSX-STOP)> -0.10. 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 31 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
If the Bayesian posterior probability is at least equal to 0.95, then the hypothesis that Superion® 
ISS is non-inferior to X-STOP® IPD® at 5-years will be accepted.  Non-informative beta(1,1) priors 
were assumed for both groups.  With these assumptions, power is 73% and type 1 error is equal to 
0.05.  However, updated Month 36 results reflect a device group difference equal to 5.7%.  
Conservatively assuming a 5% difference, power increases to 87% and remains above 80% for 
device group differences larger than about 3.5%. 
10.6 
Superiority 
The following superiority hypotheses will be tested if non-inferiority is demonstrated.  By the 
closed testing principle there is no need for multiplicity adjustment.  
Ho: CCSSuperion – CCSX-STOP ≤   0 (not superior) 
Ha: CCSSuperion – CCSX-STOP >   0 (superior) 
The posterior probability that (CCSSuperion – CCSX-STOP) > 0 will be determined using Beta(1,1) 
priors for 5-year  CCSSuperion and for 5-year CCSX-STOP.  If the posterior probability of superior is 
at least equal to 0.95, then a superiority claim will be made. 
10.7 
Missing Data and Loss-to-Follow-Up 
In order to best preserve an intent-to-treat philosophy, the primary analysis will be done on the 
mITT group.  Those subjects who withdraw, or who are lost (LTFU) after randomization, will be 
included in the analysis using Bayesian imputation.  This analysis will be the primary analysis, but 
recognizing that there is no way, statistically, to handle these subjects without possibly introducing 
bias, a tipping point analysis will be conducted. 
 
The tipping point sensitivity analysis will be conducted in which missing values in each group are 
separately assumed to be either successes or failures. Treatment group differences will be 
computed based on all possible combinations of assigning success or failure to the primary overall 
success endpoint to the patients in the two groups.  For example, one scenario will be that all 
missing Superion device observations are failures and all missing X-STOP observations are 
successes. The next scenario would have one success and the remaining missing values as failure 
for Superion and all missing X-STOP as successes. For each scenario, the Bayesian posterior 
probability of non-inferiority will be determined. These results will be plotted using a dot plot with 
the number of missings assumed as failures for Superion on the x-axis and the number of missing 
assumed as failures for controls on the Y-axis.  The dots will be color coded to indicate whether 
or not the primary statistical conclusion changes under each individual scenario.  If the fraction of 
scenarios in which the statistical conclusion changes is small, the primary results will have been 
shown to be robust against assumptions concerning missingness. 
10.8 
Stratified Analysis for Multiple-Level Analysis 
A logistic regression analysis will be conducted with level (one-level and two-level) and treatment 
as additive factors.  Additionally an interaction effect between level and treatment will be included. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 32 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
10.9 
Secondary Endpoints 
Secondary continuous effectiveness endpoints will be summarized by treatment group over time 
and as changes over time with descriptive statistics including means, standard deviations, median, 
minimum and maximum values. Secondary categorical effectiveness endpoints will be 
summarized by treatment group over time using counts and percentages.   Descriptive effect size 
measures such as standardized mean differences will be presented as an aid in comparing 
magnitudes of groups differences across endpoints measured on different scales. Secondary 
endpoints analyses may also include other traditional frequentist confidence intervals and p-values 
for superiority. 
10.10 Safety Analyses 
Assessment of safety will primarily be based on the incidence and severity of complications and 
adverse reactions associated with the treatment.  Adverse event rates will be summarized by type 
of AE and for specific AEs in two ways: 1) per patient using counts and percentages and 2) by 
event, summarizing event counts by visit interval over time.  Device and procedure related events 
will be summarized by severity.  Events listings will be provided that include details such as 
relatedness, severity, onset and resolution status will be provide for all events and for relevant 
subsets of events such as serious events and related events. 
10.11 Site Heterogeneity 
Site poolability will be evaluated using a random effects meta-analysis approach using the R 
package metafor to implement the analysis.  True effects are assumed to be normally distributed 
with mean µ and variance σ2.    
By imposing a specified distribution on the site-to-site variability, i.e. a normal distribution with 
mean m and variance t2, sensitivity to small sample sizes in individual sites is reduced and the 
parameters reflecting the magnitude of site-to-site variability are naturally derived.  The 
quantitative measure of the magnitude of heterogeneity is I2.  I2 is the fraction of t2 that is due to 
effect size heterogeneity, as opposed to sampling variance.  Fractions 25% and less are considered 
small.  If there is significant site to site variability, the impact on this variability will be evaluated 
using a Bayesian hierarchical model estimated using WinBUGS. 
This will be done by translating hypotheses of interest to the log odds ratio scale and using MCMC 
to determine the Bayesian posterior probabilities of the described results.  Poolability according to 
baseline demographic and disease severity status will be evaluated in descriptive stratified 
analyses. 
11 
Risks 
The potential risks for subjects enrolled in the trial include those related to surgery, lumbar spine 
surgery, interspinous spacers (including the X-STOP® IPD®, Superion® ISS and other 
interspinous spacers) and instrumentation, the Superion® ISS, or radiographs for the study that 
are not standard of care.  There is always a chance that unforeseen risks may occur. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 33 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Risks generally associated with any surgery include: 
• anesthetic medication reactions 
• surgery at the incorrect location, side or level 
• blood loss, blood vessel damage, phlebitis or hematoma 
• blood transfusion which may cause circulatory collapse, blood incompatibility, kidney 
damage, hepatitis, infection with HIV  
• myocardial infarction or circulatory problems 
• deep vein thrombosis, pulmonary embolism or thrombus formation in other vessels 
• stroke 
• fever or infection 
• pneumonia 
• injury to muscle, soft tissues or nerves 
• wound swelling, draining or delayed healing 
• discomfort and rehabilitation associated with recovery from surgery 
• inability to perform certain tasks, such as lifting, exercising etc. 
• death 
 
Risks associated with lumbar spine surgery include: 
• damage to nerve roots or the spinal cord causing partial or complete sensory or motor 
loss (paralysis) 
• loss of bladder and/or bowel functions 
• dural leaks (tears in the tissue surrounding and protecting the spinal cord) 
• instruments used during surgery may break or malfunction which may cause damage to 
the operative site or adjacent structures 
• fracture, damage or remodeling of adjacent anatomy, including bony structures or soft 
tissues during or after surgery 
• new or worsened back or leg pain 
 
Risks associated with lumbar spine implants (including the X-STOP® IPD®, Superion® ISS 
and other interspinous spacers) and associated instruments include: 
• sensitivity or allergy to the implant material 
• failure of the device/procedure to improve symptoms and/or function  
• pain and discomfort associated with the operative site or presence of implants 
• implant malposition or incorrect orientation 
• spinous process fracture 
• wear debris which may damage surrounding soft tissues including muscle or nerve 
• scar tissue may form at implant site 
• migration or dislodgement of the implant from the original position so that it becomes 
ineffective or causes damage to adjacent bony or soft tissues including nerve 
• implant may loosen, fatigue, deform, break or disassemble which may require another 
operation to remove the implant and may require another method of treatment 
• re-operation to remove or replace the implant 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 34 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Risks specifically associated with the Superion® ISS include: 
• implant may deform, break or disassemble; specifically the cam lobes may collapse or 
fail to lock 
• other unexpected reactions may also occur 
 
Risks Associated with Radiographs of the Lumbar Spine 
The series of radiographs required for this study are similar to the standard of care for patients with 
Lumbar Spinal Stenosis treated with traditional surgical procedures such as laminectomy with or 
without spinal fusion.  The risk of any side effects from this low level of exposure is very small. 
A 4-view X-ray of the lumbar spine (AP, lateral, flexion, extension) will be obtained at baseline, 
and at 6 weeks, 3, 6, 12, 18 and 24 month follow-up visits with a 2-view at the immediate post-
operative time point.  It is estimated that the total millirems will be less than 200 millirems per 
visit (for a 4 view x-ray) or no more than 1300 millirems for this study.  This exposure can be 
compared to the allowable annual radiation dose for nuclear medicine/radiation oncology workers 
of 1800 millirems per year.51 
Fluoroscopy Exposure 
Fluoroscopy was used intra-operatively to ensure correct placement of the Superion® ISS device, 
and the X-STOP® IPD® device, between the spinous processes.  Doses are similar to those used 
during fusion surgery or to administer non-operative treatments such as epidural injections, facet 
blocks or nerve root blocks.  Sources of morbidity associated with the use of fluoroscopic guidance 
include, but are not limited to: early transient erythema, main erythema reaction, temporary 
epilation, permanent epilation, and dermal necrosis. These are usually associated with longer 
radiation exposures and higher doses than expected during the study surgery. 
12 
Benefit Analysis 
The clinical benefits of the Superion® ISS have been documented through clinical study under IDE 
No. G070118, and may include the relief of symptoms associated with LSS.  The potential benefit 
for subjects who are enrolled in the clinical investigation and receive the FDA-approved X-STOP® 
IPD® may include the relief of symptoms associated with LSS.  An additional potential benefit for 
subjects who are enrolled in the clinical investigation and who receive the Superion® ISS is the 
possibility of less patient morbidity and tissue trauma, since the device can be percutaneously 
inserted through a 15 mm incision compared to the 4 cm (40 mm) incision needed to implant the 
X-STOP® IPD® device. 
 
Although subjects enrolled in the clinical investigation may receive no direct benefit from 
participating, the knowledge gained from this investigation may benefit both physicians treating 
patients and patients who have LSS by generating data regarding the safety and outcome of the 
treatments. 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 35 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
13 
Investigator Responsibilities 
13.1 
IRB Approval 
This study must have initial and continuing approval (at least annual) from an Institutional Review 
Board (IRB) responsible for approving clinical studies. This can be a local or central IRB. 
Screening or enrollment of subjects into the trial did not commence until the IRB approval letter 
was received by the Sponsor.  In addition, a copy of the IRB approval letter must be filed on-site 
in the Investigator’s study binder.  Where appropriate, amendments to the protocol will be 
submitted for IRB review and approval before implementation. 
13.2 
Protocol Adherence 
The Investigator(s) agree to conduct the study in accordance with this protocol.  Prior to beginning 
the study, the Investigator(s) must sign the Investigator Agreement and the Protocol Signature 
Page of this protocol. 
An Investigator must not make any changes in the study without first receiving approval in writing 
from the Sponsor and IRB, except when necessary to eliminate apparent immediate hazards to a 
subject. 
13.3 
Review of Source Documents 
The Investigator(s) agrees that the Sponsor’s employees or designees, as well as FDA designees 
will have the right to audit and review pertinent medical records relating to this clinical trial. 
13.4 
Record of Device Inventory 
The Investigator(s) will maintain a Device Accountability Log of all investigational devices 
received, used, or returned during this study. The Device Accountability Log should be available 
during monitoring visits.  All investigational devices not used in this study must be returned to the 
Sponsor before or at the completion of the study or at the Sponsors request.   
13.5 
Data Recording and Record Retention 
1. All data will be recorded on Case Report Forms for each subject enrolled in the study 
as well as in the subject records (source documentation). 
2. The Sponsor or Sponsor’s designee will review completed Case Report Forms, along 
with source documentation.  The Investigator(s) will ensure that the medical records 
are made available for review by the study monitor or FDA, as required. 
3. All subject study records are to be maintained in a secure storage facility until notified 
by the Sponsor that the records may be discarded.  This includes the following 
documentation: 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 36 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
i) Case Report Forms, Informed Consents and enrollment logs 
ii) Device Accountability Logs and device shipment receipts of all devices 
shipped to the site 
iii) Correspondence with the IRB, Sponsor, FDA, Monitor, or other Investigators 
iv) Study protocol and any amendments issued 
v) Protocol and Informed Consent approvals from the IRB 
vi) Clinical Study Agreement and curricula vitae of Investigator(s), and the site 
personnel signature form 
13.6 
Notification Reporting 
The Investigator(s) is responsible for all reporting required per the IRB.  
14 
Sponsor Obligations 
14.1 
Investigator(s) Training 
Prior to the first procedure, the Sponsor provided appropriate training to each Investigator that 
included didactic and hands on elements, e.g., cadaver lab, sawbones, model.  Training addressed 
topics including surgical procedures, selection of appropriate implant sizes, instrumentation for 
implantation, indications for use of the device, contraindications and management of 
complications.  The Sponsor also provided appropriate training to the operating room staff at each 
investigational site.  Investigators were trained on use of the control device.  Each site was 
permitted to enroll up to 2 non-randomized patients to receive the Superion® ISS as training cases 
prior to randomizing the first patient. 
14.2 
Sponsor Study Termination 
The Sponsor may close enrollment or terminate the study at any site, at any time, for any of the 
reasons listed below.  If a site was closed to enrollment or terminated before enrolling randomized 
patients, the site could be replaced in the study.  Patients identified as training cases that receive 
implants will be followed until they reach their 60 month follow-up or the study is terminated. 
 
1. Non-compliance to GCP guidelines or protocol 
2. Failure to enroll subjects in a timely manner 
3. Protocol deviations 
4. Inaccurate or incomplete data 
5. Unsafe or unethical practices 
6. Safety or efficacy considerations 
7. Administrative decision 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 37 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
14.3 
Study Monitoring and Frequency of Monitoring Visits 
Study monitoring will be carried out in compliance with FDA regulations (21CFR 812) and all 
GCP guidelines.  The clinical investigation will be monitored throughout its active phase, i.e., until 
60 month follow-up is complete for all subjects.  The first Monitoring Visit occurred shortly after 
the first subject was enrolled and treated at the site.  Subsequent Monitoring Visits will occur as 
the frequency of follow-up dictates, but no less than annually. 
Periodic Monitoring Visit Activities 
1. The Monitor’s visit to the clinical site will include review of: 
a. 
Subject Source Documentation 
b. 
Case Report Forms 
c. 
Informed Consents 
d. 
Protocol Adherence 
e. 
Investigational Device Accountability 
2. Reports: 
a. 
The Monitor should complete a report documenting completion of each 
Periodic Monitoring visit. 
3. Site Close-out Activities 
a. 
When the study has been completed or terminated, the Monitor will assure 
that all site Close-out activities have been completed. 
b. 
The Monitor should complete a report documenting completion of site 
Close-out Monitoring visit. 
15 
Informed Consent 
A copy of the proposed Informed Consent document should be submitted to Sponsor for review 
and approval before submission to the IRB.  Study enrollment may not have begun until Sponsor 
reviewed the document and it was approved by the IRB. 
All subjects enrolling in the study: 
a. Were informed of the investigational nature of the study  
b. Were given the opportunity to ask any questions regarding the study treatment 
c. Voluntarily and willingly signed the Informed Consent prior to study treatment 
d. Were given a copy of the Informed Consent 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 38 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
List of Appendices 
 
Appendix A: Visit Schedule 
 
Appendix B: Patient Questionnaires 
 
Zurich Claudication Questionnaire 
 
 
Oswestry Disability Index 
 
 
Visual Analog Scale 
 
 
SF-12 
 
VertiFlex® Patient Satisfaction Survey 
 
 
Bibliography 
 
 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 39 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
aLumbar spine x-rays and MRI/CT taken within 3 months of enrollment can be used to confirm eligibility. 
bIn order to confirm eligibility, at the Investigator’s discretion, subjects previously diagnosed with osteoporosis, osteopenia, osteomalacia, female subjects 
over the age of 65, and post-menopausal female subjects under the age of 65 with any of the risk factors for osteoporosis, will have DEXA scans 
performed prior to study entry. 
 
Appendix A:  Visit Schedule 
 
Screening
-Baseline 
Surgical 
Treatment 
Discharge 
(±0-7 days) 
6-week 
(±2 weeks) 
3-month 
(±2 weeks) 
6-month 
(±1 month) 
12-month 
(±2 months) 
18-month 
(±2 months) 
24-monthc 
(±2 months) 
36-monthc 
(±2 months) 
48-monthc 
(±2 months) 
60-monthc 
(±2 months) 
Study Visit Window 
 
Day 0 
0-7 days 
4-8 wks 
10-14 wks 
5-7 mos 
10-14 mos 
16-20 mos 
22-26 mos 
22-26 mos 
22-26 mos 
22-26 mos 
Signed Informed Consent 
X 
 
 
 
 
 
 
 
 
 
 
 
Demographic Information 
X 
 
 
 
 
 
 
 
 
 
 
 
Complete History & Physical  
X 
 
 
 
 
 
 
 
 
 
 
 
Randomization  
X 
 
 
 
 
 
 
 
 
 
 
 
Standing AP & Lateral Lumbar 
Spine X-rays 
Xa 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Flexion / Extension Lateral 
Lumbar Spine X-rays 
Xa 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Lumbar Spine MRI/CT Scan 
Xa 
 
 
 
 
 
 
 
 
 
 
 
DEXA Scanb 
As needed 
 
 
 
 
 
 
 
 
 
 
 
SF-12 –Health Survey (v2) 
X 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Zurich Claudication 
Questionnaire (ZCQ) 
X 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Oswestry Disability Index (v2) 
X 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Neurological Status 
X 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Visual Analogue Scale  
X 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
VertiFlex® Patient Satisfaction 
Questionnaire 
 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Assess Adverse Events 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
P a g e  | 40 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Appendix B:  Patient Questionnaires 
 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
Bibliography 
 
1.  
Alvarez, J. A., and R. H. Hardy Jr. Lumbar Spine Stenosis: a Common Cause of Back and 
Leg Pain. Am Fam Physician 57, no. 8 (1998): 1825-34, 1839-40. 
2. 
Amundsen, T., H. Weber, F. Lilleas, H. J. Nordal, M. Abdelnoor, and B. Magnaes. Lumbar 
Spinal Stenosis. Clinical and Radiologic Features. Spine 20, no. 10 (1995): 1178-86. 
3. 
Binder, D. K., M. H. Schmidt, and P. R. Weinstein. Lumbar Spinal Stenosis. Semin Neurol 
22, no. 2 (2002): 157-66. 
4. 
Fritz, J. M., A. Delitto, W. C. Welch, and R. E. Erhard. Lumbar Spinal Stenosis: a Review 
of Current Concepts in Evaluation, Management, and Outcome Measurements. Arch Phys 
Med Rehabil 79, no. 6 (1998): 700-8. 
5. 
Furman MB. Spinal stenosis and nuerogenic claudication. Web page,  [accessed 24 October 
2006]. Available at www.emedicine.com. 
6. 
Kikuchi, S., M. Hasue, K. Nishiyama. Anatomic and Clinical Studies of Radicular 
Symptoms. Spine 9, no. 1 (1984): 23-30. 
7. 
Verbiest, H. A Radicular Syndrome From Developmental Narrowing of the Lumbar 
Vertebral Canal. J Bone Joint Surg Br 36-B, no. 2 (1954): 230-7. 
8.  
US Department of Health and Human Services, Agency for Healthcare Research and 
Quality. Treatment of Degenerative Lumbar Spinal Stenosis. Rockville, MD, 2001. 
9.  
California Technology Assessment Forum. (21 June 2006). An Interspinous Process 
Distractor (X-STOP) for the Treatment of Spinal Stenosis of the Lumbar Spine; A 
Technology Assessment. Retrieved 10 October 2007 from ctaf.org 
10.  Davenport-Fortune, P. Neurogenic Claudication. J Am Acad Nurse Pract 6, no. 4 (1994): 
177-82. 
11.  Garfin, S. R., H. N. Herkowitz, and S. Mirkovic. Spinal Stenosis. Instr Course Lect 49 
(2000): 361-74. 
12.  Goh, K. J., W. Khalifa, P. Anslow, T. Cadoux-Hudson, and M. Donaghy. The Clinical 
Syndrome Associated With Lumbar Spinal Stenosis. Eur Neurol 52, no. 4 (2004): 242-9. 
13.  Johnsson, K. E. Lumbar Spinal Stenosis. A Retrospective Study of 163 Cases in Southern 
Sweden. Acta Orthop Scand 66, no. 5 (1995): 403-5. 
14.  Katz, J. N., M. Dalgas, G. Stucki, N. P. Katz, J. Bayley, A. H. Fossel, L. C. Chang, and S. 
J. Lipson. "Degenerative Lumbar Spinal Stenosis. Diagnostic Value of the History and 
Physical Examination." Arthritis Rheum 38, no. 9 (1995): 1236-41. 
15.  Alexander JT. Lumbar Spinal Stenosis: Diagnosis and Treatment Options. Duval County 
Medical Society, Jacksonville Medicine  (1999).  
16.  Amundsen T, et.al.. Lumbar Spinal Stenosis: Conservative or Surgical Management? A 
Prospective 10-year Study. Spine, 25 no.11 (2000):1424-35 
                                               

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
                                                                                                                                                       
17.  Atlas, S. J., and A. Delitto. Spinal Stenosis: Surgical Versus Nonsurgical Treatment. Clin 
Orthop Relat Res 443 (2006): 198-207. 
18.  Atlas, S. J., R. B. Keller, D. Robson, R. A. Deyo, and D. E. Singer. Surgical and 
Nonsurgical Management of Lumbar Spinal Stenosis: Four-Year Outcomes from the Maine 
Lumbar Spine Study. Spine 25, no. 5 (2000): 556-62. 
19.  Herno, A., O. Airaksinen, T. Saari, and M. Luukkonen. Lumbar Spinal Stenosis: A 
Matched-Pair Study of Operated and Non-Operated Patients. Br J Neurosurg 10, no. 5 
(1996): 461-5. 
20. Johnsson, K. E., A. Uden, and I. Rosen. The Effect of Decompression on the Natural 
Course of Spinal Stenosis. A Comparison of Surgically Treated and Untreated Patients. 
Spine 16, no. 6 (1991): 615-9. 
21.  Aalto, T. J., A. Malmivaara, F. Kovacs, A. Herno, M. Alen, L. Salmi, H. Kroger, J. 
Andrade, R. Jimenez, A. Tapaninaho, V. Turunen, S. Savolainen, and O. Airaksinen. 
Preoperative Predictors for Postoperative Clinical Outcome in Lumbar Spinal Stenosis: 
Systematic Review. Spine 31, no. 18 (2006): E648-63. 
22.  Airaksinen, O., A. Herno, V. Turunen, T. Saari, and O. Suomlainen. Surgical Outcome of 
438 Patients Treated Surgically for Lumbar Spinal Stenosis. Spine 22, no. 19 (1997): 2278-
82. 
23.  Postacchini, F. Management of Lumbar Spinal Stenosis. J Bone Joint Surg Br 78, no. 1 
(1996): 154-64. 
24.  Postacchini, F. Surgical Management of Lumbar Spinal Stenosis. Spine 24, no. 10 (1999): 
1043-7. 
25.  Spivak, J. M. Degenerative Lumbar Spinal Stenosis. J Bone Joint Surg Am 80, no. 7 
(1998): 1053-66. 
26.   Yukawa, Y., L. G. Lenke, J. Tenhula, K. H. Bridwell, K. D. Riew, and K. Blanke. A 
Comprehensive Study of Patients with Surgically Treated Lumbar Spinal Stenosis with 
Neurogenic Claudication. J Bone Joint Surg Am 84-A, no. 11 (2002): 1954-9. 
27.  Atlas, S. J., R. A. Deyo, R. B. Keller, A. M. Chapin, D. L. Patrick, J. M. Long, and D. E. 
Singer. "The Maine Lumbar Spine Study, Part III. 1-Year Outcomes of Surgical and 
Nonsurgical Management of Lumbar Spinal Stenosis." Spine 21, no. 15 (1996): 1787-94; 
discussion 1794-5. 
28.  Ciol, M. A., R. A. Deyo, E. Howell, and S. Kreif. "An Assessment of Surgery for Spinal 
Stenosis: Time Trends, Geographic Variations, Complications, and Reoperations." J Am 
Geriatr Soc 44, no. 3 (1996): 285-90. 
29.  Fischgrund, J. S., M. Mackay, H. N. Herkowitz, R. Brower, D. M. Montgomery, and L. T. 
Kurz. 1997 Volvo Award Winner in Clinical Studies. Degenerative Lumbar 
Spondylolisthesis With Spinal Stenosis: a Prospective, Randomized Study Comparing 
Decompressive Laminectomy and Arthrodesis with and Without Spinal Instrumentation. 
Spine 22, no. 24 (1997): 2807-12. 
30.  Fritzell, P., O. Hagg, P. Wessberg, and A. Nordwall. 2001 Volvo Award Winner in Clinical 
Studies: Lumbar Fusion Versus Nonsurgical Treatment for Chronic Low Back Pain: A 

VertiFlex®, Inc., SPACER Trial 
Protocol #: 08-VISS-01 
 
Rev. 19 June 2015 
 
CONFIDENTIAL AND PROPRIETARY INFORMATION. This document and the information contained herein 
may not be reproduced, used or disclosed without the written permission of VertiFlex®, Inc. 
                                                                                                                                                       
Multicenter Randomized Controlled Trial from the Swedish Lumbar Spine Study Group. 
Spine 26, no. 23 (2001): 2521-32; discussion 2532-4. 
31.  Herno, A., K. Partanen, T. Talaslahti, E. Kaukanen, V. Turunen, O. Suomalainen, and O. 
Airaksinen. Long-Term Clinical and Magnetic Resonance Imaging Follow-Up Assessment 
of Patients with Lumbar Spinal Stenosis after Laminectomy. Spine 24, no. 15 (1999): 1533-
7. 
32.  Herno A., et al., Computed Tomography Findings 4 Years After Surgical Management of 
Lumbar Spinal Stenosis. Spine, 24 no. 21 (1999): 2234-2239 
33.  Inufusa, A., H. S. An, T. H. Lim, T. Hasegawa, V. M. Haughton, and B. H. Nowicki. 
Anatomic Changes of the Spinal Canal and Intervertebral Foramen Associated with 
Flexion-Extension Movement. Spine 21, no. 21 (1996): 2412-20. 
34.  Jonsson, B., M. Annertz, C. Sjoberg, and B. Stromqvist.  A Prospective and Consecutive 
Study of Surgically Treated Lumbar Spinal Stenosis. Part I: Clinical Features Related to 
Radiographic Findings. Spine 22, no. 24 (1997): 2932-7. 
35.  Jonsson, B., and B. Stromqvist. Symptoms and Signs in Degeneration of the Lumbar Spine. 
A Prospective, Consecutive Study of 300 Operated Patients. J Bone Joint Surg Br 75, no. 3 
(1993): 381-5. 
36. Stucki, G., et al. Contribution of neuromuscular impairment to physical functional status in 
patients with lumbar spinal stenosis. J Rheumatol, 1994. 21(7): p. 1338-43. 
37. Herno, A., O. Airaksinen, and T. Saari. Long-term results of surgical treatment of lumbar 
spinal stenosis. Spine, 1993. 18(11): p. 1471-4. 
38.  Bridwell, K.H. Lumbar spinal stenosis. Diagnosis, management, and treatment. Clin 
Geriatr Med, 1994. 10(4): p. 677-701. 
39.  McNeill, T.W., M.D., Decompressive Laminectomy, in Lumbar Spinal Stenosis, G.B. 
Andersson and T.W. McNeill, Editors. 1991. p. 339. 
40  Zucherman, J. F., K. Y. Hsu, C. A. Hartjen, T. F. Mehalic, D. A. Implicito, M. J. Martin, D. 
R. Johnson 2nd, G. A. Skidmore, P. P. Vessa, J. W. Dwyer, S. Puccio, J. C. Cauthen, and 
R. M. Ozuna. A Prospective Randomized Multi-Center Study for the Treatment of Lumbar 
Spinal Stenosis With the X-STOP Interspinous Implant: 1-Year Results. Eur Spine J 13, 
no. 1 (2004): 22-31. 
41.  St. Francis Medical Technologies, Inc. Summary of Safety and Effectiveness, Submitted to 
FDA for PMA PO40001. 21 Nov 2005.