TOPS vs. Minimally Invasive Lumbar Fusion | Which Is Right for You?
Clinical Perspectives · Spine Surgery · Naples FL
TOPS vs. Minimally Invasive
Lumbar Fusion — Which Is Right for You?
Both TOPS and minimally invasive lumbar fusion are excellent operations. They treat the same symptoms — back pain, leg pain, neurogenic claudication from stenosis with spondylolisthesis — through different mechanisms, and the right choice depends entirely on anatomy. Right patient selection is everything.
The shared problem:
spondylolisthesis with stenosis
Most patients who end up comparing TOPS to lumbar fusion arrive at the same place: they have lumbar spinal stenosis with degenerative spondylolisthesis — a slip of one vertebra on another, with narrowing of the spinal canal producing leg pain, claudication, and often significant back pain. Conservative care has failed. Surgery is indicated. The question is which surgery.
For most of the last several decades, that question had one answer: lumbar fusion. Decompress the canal, stabilize the segment permanently, eliminate the slip. It works. MIS fusion works well. But it is not the only answer anymore.
What MIS lumbar fusion actually means —
it has many forms
When a surgeon says "minimally invasive lumbar fusion," they may mean any of several fundamentally different approaches. They all achieve the same biological goal — permanent bony fusion across a spinal segment — but through different corridors, with different advantages and tradeoffs. Understanding which form is being proposed for you matters.
MIS-TLIF — Transforaminal Lumbar Interbody Fusion
Posterior midline approach with tubular retractors. Cage placed through the foramen. Bilateral pedicle screws. The most widely performed MIS lumbar fusion. Excellent for spondylolisthesis, works at all lumbar levels including L5-S1.
MIS-PLIF — Posterior Lumbar Interbody Fusion
Similar corridor to TLIF but bilateral cage placement through the posterior disc space. Slightly more retraction required. Robust bilateral graft surface. Less favored than TLIF at most centers due to higher nerve retraction.
LLIF / XLIF — Lateral Lumbar Interbody Fusion
Retroperitoneal approach through the flank. Large-footprint cage spanning both cortical endplates — excellent for indirect decompression and deformity correction. Effective L1-L4; not suitable at L5-S1. Often combined with posterior fixation.
ALIF — Anterior Lumbar Interbody Fusion
Anterior retroperitoneal approach. Large cage, excellent disc height restoration, minimal posterior muscle disruption. Particularly well-suited to L4-5 and L5-S1. Often combined with posterior fixation for spondylolisthesis. Requires vascular access.
OLIF — Oblique Lumbar Interbody Fusion
Approaches the disc obliquely, anterior to the psoas muscle, avoiding the lumbar plexus. Works at L2-5 and L5-S1 (with modification). Good indirect decompression profile. Avoids psoas-related thigh weakness seen with traditional LLIF.
Each of these approaches achieves the same endpoint: permanent bony fusion that eliminates segmental motion. The disc is removed. A cage is placed. Bone grows across the segment. The slip is stabilized. Pain is relieved. Done correctly in the right patient, MIS lumbar fusion produces excellent long-term outcomes. According to a systematic review of ALIF, PLIF, and TLIF by Lenz et al. (2021), all three approaches produce significant improvement in clinical outcome scores, with mean fusion rates of approximately 91%. The surgical approach is chosen based on the anatomy, the level, the degree of deformity, and the surgeon's training — not on which is generically "best."
Lenz M et al. Comparison of Different Approaches in Lumbosacral Spinal Fusion Surgery: A Systematic Review and Meta-Analysis. Asian Spine J. 2021;16(1):141-149. doi:10.31616/asj.2020.0405
What TOPS actually does —
and what it doesn’t
TOPS — the Total Posterior Spine System by Premia Spine — is not a fusion. It is a posterior dynamic stabilization device that works through facet arthroplasty: replacing the facet joints rather than fusing the vertebrae.
During a TOPS procedure, the spine is decompressed in exactly the same way it would be for any posterior lumbar surgery — the lamina, facets, ligamentum flavum, and other structures compressing the nerves are removed. Then, instead of placing a cage and fusing the segment, the TOPS device is secured to the vertebrae above and below using four standard polyaxial pedicle screws. The device stabilizes the segment against the shear forces that drive spondylolisthesis, while allowing controlled motion in all planes — flexion, extension, lateral bending, and axial rotation.
The motion that is preserved is not simply a cosmetic benefit. In the lumbar spine, segmental stiffness accelerates degeneration at adjacent levels — a well-documented phenomenon called adjacent segment disease. Fusion, by eliminating motion at one level, redistributes stress to the levels above and below. Over time, a meaningful proportion of fusion patients develop adjacent segment problems that require further surgery. TOPS, by maintaining motion at the treated level, reduces — though does not eliminate — this redistribution of stress.
The evidence —
what the FDA trial actually showed
TOPS received FDA approval in June 2023 following completion of a prospective, randomized, multicenter IDE (investigational device exemption) clinical trial comparing TOPS to transforaminal lumbar interbody fusion (TLIF). This is the same rigorous pathway required of any FDA-approved spinal implant. The trial enrolled 249 patients at 37 centers across the United States.
Based on data from PubMed, Coric et al. (2022) reported the primary 24-month results in the Journal of Neurosurgery: Spine. The composite measure of clinical success — defined as no reoperation, no device breakage, at least a 15-point improvement in Oswestry Disability Index, and no new neurological deficit — was 85% for TOPS versus 64% for TLIF (p = 0.0138). The percentage of patients achieving a minimum 15-point ODI improvement was 93% for TOPS versus 81% for TLIF (p = 0.037). Importantly, flexion-extension range of motion at the operative level was maintained from preoperatively (3.85°) to 24 months (3.86°) in the TOPS cohort. The surgical reintervention rate was lower for TOPS (5.9%) than TLIF (8.8%).
Coric D, Nassr A, Kim PK, et al. Prospective, randomized controlled multicenter study of posterior lumbar facet arthroplasty for the treatment of spondylolisthesis. J Neurosurg Spine. 2022;38(1):115-125. doi:10.3171/2022.7.SPINE22536
These are results from an RCT with independent core laboratory radiographic assessments — the same standard of evidence used to approve cervical disc replacement, lumbar disc replacement, and every major spinal device. The comparison arm was not open fusion but minimally invasive TLIF, which is itself a high-performing operation.
The 1-year interim data, published by Pinter et al. (2022) in Clinical Spine Surgery from the Mayo Clinic and 25 other sites, confirmed statistically significant improvement across all patient-reported outcome measures — ODI, VAS back pain, VAS leg pain, and Zurich Claudication Questionnaire — with all operative segments remaining mobile at 1-year follow-up and a 5.9% reoperation rate.
Pinter ZW, Freedman BA, Nassr A, et al. A Prospective Study of Lumbar Facet Arthroplasty in the Treatment of Degenerative Spondylolisthesis and Stenosis: Results from the Total Posterior Spine System (TOPS) IDE Study. Clin Spine Surg. 2023;36(2):E59-E69. doi:10.1097/BSD.0000000000001365
The longest available follow-up data comes from European centers that used TOPS before FDA approval. Smorgick et al. (2019) published 11-year outcomes from the original Israeli cohort in the Journal of Neurosurgery: Spine: mean VAS leg pain dropped from 83.5 preoperatively to 17 at 11 years; mean VAS back pain dropped from 56.2 to 14; mean ODI dropped from 49.1 to 16. No progression of spondylolisthesis was observed in any patient. No adjacent level stenosis requiring surgery developed. One patient converted to posterolateral fusion due to an early device malfunction at the original implantation.
Smorgick Y, Mirovsky Y, Floman Y, et al. Long-term results for total lumbar facet joint replacement in the management of lumbar degenerative spondylolisthesis. J Neurosurg Spine. 2020;32(1):36-41. doi:10.3171/2019.7.SPINE19150
On economics: Ament et al. (2024) updated the cost-effectiveness analysis from the full 305-patient FDA dataset and found TOPS to be cost-dominant over TLIF at 2 years with an incremental cost-effectiveness ratio of –$9,637/QALY — meaning TOPS produces more quality-adjusted life-years at lower cost. This finding held across all payer types and surgical settings in sensitivity analyses.
Ament JD, Petros J, Zabehi T, et al. A prospective study of lumbar facet arthroplasty in the treatment of degenerative spondylolisthesis and stenosis: cost-effective assessment from the TOPS IDE Study. Spine J. 2024;24(6):1001-1014. doi:10.1016/j.spinee.2024.01.004
The candidacy question —
who is right for TOPS, and who is right for MIS fusion
This is the central clinical question — and the one that most patients have not had answered before they arrive for a second opinion. It is not a competition between two operations. It is a matter of anatomy. Right patient selection is everything.
TOPS candidacy — what the disc must look like
TOPS works because the disc is healthy enough to continue doing its job. The device provides posterior stability and replaces the facets; the disc provides the anterior load-bearing and hydraulic function it has always provided. If the disc is significantly degenerated — substantially collapsed, with poor hydration, significant endplate changes, or meaningful disc space height loss — it can no longer perform this function adequately, and TOPS is not the right operation.
Grade I degenerative spondylolisthesisThe slip is at Grade I (up to 25% of the vertebral body width). Higher grades introduce more mechanical demand on the posterior fixation and change the risk-benefit calculation.
Moderate-to-severe lumbar stenosisConfirmed neural compression producing claudication, radiculopathy, or significant functional limitation. The decompression is the treatment; TOPS stabilizes the result.
Preserved or near-preserved disc heightThe intervertebral disc must retain meaningful height and hydration. This is assessed on MRI (T2 signal, disc height measurement) and standing lateral X-ray. A disc that is substantially collapsed is not an appropriate TOPS disc.
No significant instability beyond the slipTOPS controls the shear forces of spondylolisthesis. It is not designed for gross segmental instability, rotational instability, or high-grade deformity.
Adequate bone quality for pedicle screw fixationTOPS uses four standard polyaxial pedicle screws. Severe osteoporosis affecting screw purchase is a relative contraindication as it is for any posterior instrumented surgery.
Significant disc degeneration or height lossIf the disc is substantially degenerated on MRI, collapsed on X-ray, or has Modic endplate changes suggesting significant disc pathology, the disc cannot serve as the anterior load-bearing element. MIS fusion with interbody cage placement is the appropriate operation — the cage replaces the disc space, restores height, and provides the anterior column support that a degenerated disc can no longer offer.
Multilevel disease requiring fusionTOPS is a single-level device. Patients requiring fusion at multiple levels, or who have adjacent pathology that will need surgical treatment, are better served by fusion surgery that addresses all levels in a coordinated way.
Prior posterior surgery at the same levelSignificant scarring or altered anatomy from prior posterior surgery at the target level makes TOPS technically challenging and may preclude it. Prior discectomy at the same level may also compromise disc integrity needed for TOPS.
MIS fusion candidacy — the broader indication
MIS fusion has a broader anatomical indication than TOPS. It does not depend on disc integrity — the degenerated disc is removed, the cage is placed, and fusion creates a solid column across the segment regardless of what the disc looked like before surgery. This makes MIS fusion appropriate for a wider range of patients:
Significant disc degeneration or collapseThe most common reason a patient is a better fusion candidate than a TOPS candidate. When the disc has lost its structural integrity, interbody fusion with cage placement is the right operation.
Higher-grade spondylolisthesisGrade II or higher slips, or Grade I slips with significant translational instability on flexion-extension X-rays, are better managed with solid fusion.
Multilevel diseaseWhen two or more levels require treatment, MIS fusion — using TLIF, LLIF, ALIF, or a combination — can address all levels. TOPS is currently a single-level device.
Adjacent segment disease after prior fusionPatients with adjacent segment breakdown above or below an existing fusion are fusion candidates for the new level, not TOPS candidates.
Revision surgery with significant posterior scarringRevision cases with substantial epidural scarring, prior laminectomy defects, or altered anatomy may not be suitable for TOPS placement and are generally better managed with fusion.
The head-to-head comparison
| Factor | TOPS™ Facet Arthroplasty | MIS Lumbar Fusion (TLIF / PLIF / LLIF / ALIF / OLIF) |
|---|---|---|
| Goal | Decompress + stabilize while preserving segmental motion | Decompress + stabilize through permanent bony fusion |
| Disc treatment | ● Disc stays in place, intact — must be healthy | ✓ Disc removed, cage placed — disc quality irrelevant |
| Post-op motion | ✓ Segmental motion preserved in all planes | × Permanent elimination of segmental motion |
| Adjacent segment stress | ✓ Reduced redistribution of load to adjacent levels | ● Increased load redistribution; ASD is a known long-term risk |
| FDA IDE clinical success (2yr) | ✓ 85% composite clinical success (vs. TLIF) | ✓ 64% composite clinical success (TLIF arm, same RCT) |
| Disc requirement | Healthy, preserved disc required | No disc requirement — degenerated disc is acceptable |
| Indication breadth | Grade I spondylolisthesis with stenosis, single level, healthy disc | Broader: any grade, any disc quality, multilevel, revision |
| Long-term data | 11-year European data (Smorgick 2019) — sustained outcomes, no slip progression | Decades of fusion data — well-established long-term profile |
| Bone graft / cage | × No cage, no bone graft required | ✓ Interbody cage + bone graft/BMP |
| Surgeon certification | Required — Premia Spine certification, limited surgeons | Standard spine training — widely available |
| Cost-effectiveness (2yr) | Cost-dominant over TLIF at 2 years (Ament 2024 RCT analysis) | Established Medicare/insurance reimbursement; lower device cost |
How the decision is made in practice
In the clinic, the TOPS versus MIS fusion decision comes down to a systematic review of the MRI and standing X-rays. I am looking at three things specifically:
1. The disc. T2-weighted MRI gives a direct window into disc hydration and structural integrity. A disc with maintained signal, reasonable height, and no significant endplate changes is a TOPS disc. A disc that is dark on T2, collapsed, or showing Modic changes has lost its structural role and needs to come out — MIS fusion with interbody cage is the right operation.
2. The slip and stability. Flexion-extension standing lateral X-rays show dynamic translation across the segment. A Grade I slip that is stable in flexion-extension — where the translation doesn't worsen dramatically with movement — is a TOPS candidate. High-grade or dynamically unstable slips are fusion candidates.
3. The adjacent segments. If the levels above and below the target already show significant degeneration, locking in the target segment permanently with fusion may limit future options. Preserving motion at the target level with TOPS buys time for the adjacent segments and may delay or prevent the need for extension of surgery.
This evaluation cannot be done from a report alone. It requires direct review of the imaging by the surgeon who will operate — which is why the telemedicine second opinion begins with the patient uploading their actual MRI files, not just the radiology text report.
What both operations share —
and why the framing isn’t “better vs. worse”
Both TOPS and MIS lumbar fusion relieve back pain and leg pain from spondylolisthesis with stenosis. Both decompress the nerve roots causing the claudication and radiculopathy. Both stabilize the vertebral slip and prevent its progression. Both are performed through small incisions with modern instrumentation. Both have excellent outcomes data in appropriately selected patients.
The framing of "TOPS is better than fusion" or "fusion is better than TOPS" is clinically incorrect. The framing that is correct: for the patient with Grade I spondylolisthesis, moderate-to-severe stenosis, and a healthy intact disc, TOPS offers motion preservation and superior composite clinical success in the RCT data. For the patient with a degenerated disc, higher-grade slip, multilevel disease, or prior surgery, MIS fusion remains the right operation and produces excellent results.
Most patients recommended fusion in the United States have never been told whether they are a TOPS candidate. Not because they aren't — but because their surgeon is not certified to implant it. That is the conversation this second opinion is designed to have.
for your specific anatomy
Upload your MRI and standing X-rays before your telemedicine appointment. Dr. Katsevman reviews all imaging personally. The consultation identifies whether your disc is a TOPS disc, whether your slip and stability profile fits TOPS candidacy, and — if fusion is the right operation — which of the MIS fusion approaches is most appropriate for your anatomy and the level involved.
Request a ConsultationReferences — PubMed-verified
- Coric D, Nassr A, Kim PK, et al. Prospective, randomized controlled multicenter study of posterior lumbar facet arthroplasty for the treatment of spondylolisthesis. J Neurosurg Spine. 2022;38(1):115-125. doi:10.3171/2022.7.SPINE22536
- Pinter ZW, Freedman BA, Nassr A, et al. A Prospective Study of Lumbar Facet Arthroplasty in the Treatment of Degenerative Spondylolisthesis and Stenosis: Results from the Total Posterior Spine System (TOPS) IDE Study. Clin Spine Surg. 2023;36(2):E59-E69. doi:10.1097/BSD.0000000000001365
- Smorgick Y, Mirovsky Y, Floman Y, et al. Long-term results for total lumbar facet joint replacement in the management of lumbar degenerative spondylolisthesis. J Neurosurg Spine. 2020;32(1):36-41. doi:10.3171/2019.7.SPINE19150
- Ament JD, Petros J, Zabehi T, et al. A prospective study of lumbar facet arthroplasty: cost-effective assessment from the TOPS IDE Study. Spine J. 2024;24(6):1001-1014. doi:10.1016/j.spinee.2024.01.004
- Lenz M, Mohamud K, Bredow J, et al. Comparison of Different Approaches in Lumbosacral Spinal Fusion Surgery: A Systematic Review and Meta-Analysis. Asian Spine J. 2021;16(1):141-149. doi:10.31616/asj.2020.0405
- Li XC, Huang CM, Zhong CF, et al. Minimally invasive procedure reduces adjacent segment degeneration and disease: New benefit-based global meta-analysis. PLoS One. 2017;12(2):e0171546. doi:10.1371/journal.pone.0171546
