The TOPS™ System has been studied extensively—both clinically and in pre-clinical testing. Below are some of the highlighted materials on the device.

Anekstein et al. published an 11-year follow-up study of 10 patients who were treated with the TOPS System. The primary indication for that study was neurogenic claudication due to spinal stenosis with single level degenerative spondylolisthesis. The study enrolled 5 males and 5 females aged 52-69 years (average 61.3 years). Outcome measures included VAS for leg and back pain, the Oswestry Disability Index (ODI) and the SF-36 health survey. These measures were administered preoperatively, and at 6 weeks, 3 months, 6 months, and at 1, 2, 3, 7 and 11 years.

There was one device-related failure 3 months post-surgery. X-rays showed that an internal component was damaged leading to a locking of the device. However, the screws were solidly anchored to the spine. After the 6-month follow-up, this patient underwent revision to replace the motion implant with fusion rods. No complications resulted from the fusion surgery. A minor design change in the prosthesis provided a solution to this rare complication, as confirmed by biomechanical testing of the alteration. The remaining 9 patients were seen at 1, 2, 3, 7 and 11-year follow-up.

Independent radiographic analysis at eleven (11) years revealed no evidence of spontaneous fusion or screw loosening or breakage. Flexion-extension and lateral bending views showed the TOPS implant to be mobile; and the patients demonstrated well-preserved motion clinically. MRI demonstrated no cases of stenosis or spondylolisthesis at the segment adjacent to the stabilize segment at 11 years, although progressive degeneration could be seen at 2, 3 and 4 levels above the index level in three patients.

All outcome measures demonstrated a statistically significant difference between pre and postoperative scores (p<0.05). The results are summarized in Table 1 below.

The TOPS System was clinically investigated in a randomized multi-center prospective clinical trial in the United States. The TOPS System was prospectively studied in a 1:1 randomization to traditional posterolateral fusion. Patients either received the TOPS device or a posterolateral fusion with either a DePuy (Johnson & Johnson) or a Stryker pedicle screw and fusion rod system. Patients were seen at 6 weeks, 3 months, 6 months, one year, and annually thereafter. Data collected included Oswestry Disability Index scores, VAS (pain) scores for leg and back, neurological assessments, and radiographic assessments.

The intent of this study was to complete the collection of clinical data on subjects enrolled in the TOPS IDE clinical trial (#G060063) sponsored by Impliant.

Six sites received IRB approval for continued follow-up and at those sites a total of 46 subjects who were enrolled returned for no less than two-year follow-up (out of a total of 54 subjects who were originally enrolled at six sites).
To the 2016 Annual Update, in the FDA report, 18 of the original 24 TOPS subjects remain in active follow-up and 12 of the original 21 Fusion subjects remain in active follow-up. All subjects have completed a minimum of five years of follow-up with many having additional long-term follow-up as follows:
• 6 Years – 17 subjects
• 7 Years – 15 subjects
• 8 Years – 6 subjects
• 9 Years – 2 subjects

Clinical results as demonstrated by a composite clinical endpoint assessed at 24 months, or at next available time point, shows an advantage to the TOPS System versus fusion of 86% success rate among the TOPS patients versus 64% success rate among the fusion patients. The Success Rate was measured as a composite success, with each patient required to succeed in all the criteria below to be deemed a success. Missing any of the criteria categorized the patient as a failure:
• ODI improvement of at least 15 percent
• Maintenance or improvement in neurological status
• No radiographic device failure
• No radiographic screw loosening
• Radiographic absence (TOPS) or presence (Control) of fusion
• Freedom from additional surgical intervention defined as revision, non-elective removal or supplemental fixation

The incidence of repeat index level surgery (RILS) for both treatment groups is summarized below. Through 24 months the rate of RILS in the TOPS group was 8.3% and in the fusion group was 9.5% (see Table 3). It should be noted that the one reoperation occurring in the TOPS group was for a successful dural repair at 11 days post index surgery. Table 4 reports on RILS for all patients through all available time points.

Retrospective, Single-Center Study of 17 Patients Treated with TOPSDr. Werner Lack et al. have reported on 17 patients who were treated with TOPS at a single center in Vienna, Austria. The primary indication in these patients was spondylolisthesis with relative or absolute spinal canal stenosis (15 patients), lumbar spondylarthrosis with vertebrostenosis (1 patient), and severe facetarthrosis (1 patient). The sample of 17 patients included 10 female and 7 males with age range of 54 to 82 years old. Follow-up period at the time of the report was 26 – 77 months (51-month average).

All patients underwent decompressive laminotomy and facetecomy and 3 patients received a concomitant fusion at the neighboring segment. Additionally, the 14 patients whose primary diagnosis included a spondylolisthesis underwent reduction prior to final implantation of the TOPS implant. Levels treated with TOPS included L4/5 (10 patients), L3/4 (6 patients), and L2/3 (1 patient). The average operative was 102 minutes (60 – 140).

Outcome measures assessed included:
• Operative Duration
• Intra-Operative Complications
• Post-Operative Complications
• Maintenance of Spondylolisthesis reduction

A single intra-operative complication was reported, that being an uncomplicated dural leak. Post-operatively one patient was reported as having asymptomatic screw halo at 6 months, however this patient’s original index-level procedure included a change of the screw position which could have contributed to this radiographic finding.

The average visual analog score (VAS) reduction was 7.5 at 3 months, 6.8 at 12 months, and 6.7 at the longest follow-up (average: 51 months, range: 26-77), demonstrating an average improvement of 81%. The preoperative and postoperative average ROMs were 8.2° and 7.4°, respectively.

Prospective, Single Center, Non-Randomized Study of 11 Patients Treated with TOPS
Haleem et al. have reported on 11 patients treated with TOPS at University Hospital Southampton in the United Kingdom. Primary indication for inclusion into the study was at least moderate stenosis with a Grade I spondylolisthesis. Primary exclusion criteria included previous lumbar fusion surgery, a spondylolisthesis of Grade II or greater, and any history of metabolic bone disease.

The study enrolled 11 patients however baseline evaluations for 1 patient were misplaced (this patient had successful results after surgery) and as such 10 patients are included in the analysis. These included 2 male and 8 females with an average age of 61 (range 52 – 73). All patients were Caucasian with average BMI of 28 (range 21 – 36).
Outcome measures included:
• Weight bearing AP and Lateral radiograph
• Magnetic Resonance Induction (MRI) scans – Lumbar
• Visual analog scale (VAS) for back and leg pain
• Oswestry Disability Index (ODI) Questionnaire
• SF-36 Survey
• Incidence or repeat index level surgery (RILS)

Patients were seen pre-operatively and then at 6 weeks, 3 months, 6 months, 1 year, 2 years and at the last visit—which for the cohort was an average of 5 years. The range follow-up at the final visit was 55 – 74 months, with none being lost to follow-up.

Patient reported outcomes (ODI, VAS, SF-12) all showed dramatic improvement at the first post-op time point and these improvements were maintained. The charts below summarize these data through an average 5-year follow-up.

In addition to the above, the investigators reported that none of the 10 patients included in the analysis underwent repeat index level surgery and no screw loosening was observed.

Premia Spine completed the enrollment of an FDA-approved investigation of the TOPS System in 300 patients at 37 investigational centers in the United States. Patients were randomized into either the TOPS (200 patients) or fusion arm (100 patients) of the study. The study is currently in the follow-up phase. During the clinical trial phase, the FDA designated the TOPS System as a Breakthrough Device Category, and Medicare (CMS) granted TOPS a Category B pre-approval for the coverage of routine care and services, including the device, furnished to Medicare beneficiaries enrolled into this trial.

A Prospective Study of Lumbar Facet Arthroplasty in the Treatment of Degenerative Spondylolisthesis and Stenosis: Early Cost-effective Assessment from the Total Posterior Spine (TOPS™) IDE Study.

Ament et al. reviewed the data from the FDA study to calculate the potential healthcare and societal benefits of the TOPS device versus lumbar fusion. Specifically, the study explored the cost-effectiveness and economic analysis of the TOPS System versus TLIF for patients suffering from spondylolisthesis and spinal stenosis. Patients were randomly assigned to either TOPS or TLIF surgery as part of a prospective, multi-center U.S. Food and Drug Administration (FDA) clinical trial.

 The data from the study was analyzed by Neuronomics, an independent professional corporation focusing on healthcare economic analyses. Its findings demonstrate that, even at a premium of $4,000 over the cost of a TLIF implant, TOPS still achieves cost-effectiveness at a willingness-to-pay threshold of $100,000 within one-year after surgery. Furthermore, TOPS becomes the dominant strategy when data is examined at two years and beyond. From the societal perspective, TOPS is even more highly cost-effective at one year and dominant at two years and beyond.

TOPS appears to be a highly cost-effective surgical modality compared with TLIF as a motion-preserving, non-fusion alternative for the treatment of grade 1 spondylolisthesis with lumbar spinal stenosis, with the TOPS System yielding greater quality of life at a lower total cost over time.