Total Posterior Solution (TOPS): Experimental and Investigational Status
The Total Posterior Solution (TOPS) System is currently considered experimental and investigational in the United States, as it has not yet received full FDA approval and is still undergoing clinical trials.
Current Status and Evidence
The TOPS System represents a novel approach to treating lumbar spinal stenosis and degenerative spondylolisthesis. Unlike traditional fusion procedures, TOPS is designed as a dynamic posterior arthroplasty device that:
- Replaces the facet joints after decompression
- Maintains segmental motion and flexibility
- Provides multiaxial, three-column stabilization
- Aims to reduce adjacent segment degeneration
Regulatory Status
- United States: Currently under investigation through FDA IDE (Investigational Device Exemption) trials 1
- Europe: Has received regulatory approval for use 2
Clinical Evidence
Recent high-quality evidence from a 2023 prospective, randomized controlled multicenter FDA IDE trial showed promising results:
- 249 patients (170 TOPS vs. 79 TLIF)
- Higher composite clinical success with TOPS (85%) compared to TLIF (64%) (p=0.0138)
- Greater percentage of patients achieving minimum 15-point ODI improvement with TOPS (93%) vs. TLIF (81%) (p=0.037)
- Lower surgical reintervention rate with TOPS (5.9%) vs. TLIF (8.8%)
- Maintenance of flexion/extension range of motion from preoperatively (3.85°) to 24 months (3.86°) 1
Earlier studies have also shown positive outcomes:
- A 2007 prospective pilot study of 29 patients showed 41% improvement in ODI scores and 76mm improvement in VAS pain scores at 1 year 3
- A 2022 case series demonstrated an average 81% improvement in pain scores at an average follow-up of 51 months 4
Implications for Clinical Practice
Despite promising results, several factors support the experimental classification:
- Limited long-term data: Most studies have follow-up periods of 24 months or less
- Ongoing clinical trials: The device is still being evaluated in FDA-sanctioned studies
- Absence in major guidelines: No major spine surgery guidelines currently recommend TOPS as standard of care
- Limited comparative studies: Few studies directly compare TOPS to established treatments
Patient Selection Considerations
If considering this technology in settings where it may be available:
- Best candidates appear to be those with single-level lumbar stenosis with grade I degenerative spondylolisthesis 1
- Patients seeking to maintain segmental motion and avoid fusion
- Those concerned about adjacent segment disease risk with traditional fusion
Conclusion
While the TOPS System shows promise as an alternative to fusion for treating lumbar stenosis with spondylolisthesis, its current status remains experimental and investigational in the United States. Patients should be informed about the investigational nature of this device and the limited long-term data available on its safety and efficacy.