75. Prospective, randomized study of lumbar facet replacement and lumbar interbody fusion for spondylolisthesis

Abstract

BACKGROUND CONTEXT The surgical treatment for lumbar spondylolisthesis has remained somewhat controversial. Posterior lumbar arthroplasty with facet replacement is a novel alternative to lumbar decompression and fusion. There are currently no FDA-approved devices for facet replacement. The TOPS System is a robust, pedicle screw-based biomechanical device intended to replace the facets and posterior elements following aggressive decompression. PURPOSE Lumbar facet replacement is a novel motion-preserving procedure that can be used to treat spondylolisthesis with stenosis. There is an ongoing multicenter, prospective, randomized, controlled US Food and Drug Administration (FDA) Investigation Device Exemption (IDE) trial evaluating the clinical and radiographic outcomes of an investigational facet replacement device and lumbar fusion with interbody fusion with pedicle screw fixation. STUDY DESIGN/SETTING Multicenter, prospective, randomized, US FDA Investigation Device Exemption trial. PATIENT SAMPLE The results of five high enrolling investigational sites from the prospective, randomized IDE trial comparing facet replacement (TOPS) and lumbar interbody fusion (TLiF) in the treatment of Grade I degenerative spondylolisthesis and stenosis were combined to evaluate clinical outcomes. OUTCOME MEASURES The primary clinic outcome measures included the Oswestry Disability Index (ODI) and visual analog scale (VAS) as well as re-operation rate. Patients were 2:1 randomized to artificial facet replacement vs TLIF using a monolithic PEEK interbody spacer and pedicle screw fixation. A minimum of 12 months follow-up was required for inclusion in this study. METHODS The results of five high enrolling investigational sites from the prospective, randomized IDE trial comparing facet replacement (TOPS) and lumbar interbody fusion (TLiF) in the treatment of Grade I degenerative spondylolisthesis and stenosis were combined to evaluate clinical outcomes. The primary clinic outcome measures included the Oswestry Disability Index (ODI) and visual analog scale (VAS) as well as re-operation rate. Patients were 2:1 randomized to artificial facet replacement vs TLIF using a monolithic PEEK interbody spacer and pedicle screw fixation. A minimum of 12 months follow-up was required for inclusion in this study. RESULTS A total of 129 patients have been enrolled and randomly assigned to either TOPS (n=90) or to TLIF (n= 39). A total of 63 patients were available for follow-up of at least 12 months (TOPS=47, TLIF=16). The reoperation rate for revision, removal or supplemental fixation (RRSF) for facet replacement and TLIF control was 6.7% and 12.8%, respectively. There was no significant difference between groups in baseline mean ODI (TOPS=57; TLIF=56) or VAS Back (TOPS=68; TLIF=68) and Leg scores (TOPS=83; TLIF=84). Both groups showed significant improvement in ODI (TOPS=13; TLIF=14) and VAS Back (TOPS=12; TLIF=14) and VAS Leg (TOPS=12; TLIF=10) from baseline to 12-month follow-up. At 12-month follow-up, 89% of TOPS patients and 81% of TLIF patients showed both a minimum of 15-point ODI improvement and no RRSF reoperation. CONCLUSIONS The preliminary results of this prospective, randomized study are encouraging for both TOPS and TLIF. Both lumbar facet replacement and interbody fusion groups have shown good clinical outcomes with relatively low re-operation rates. There was a trend toward lower reoperation rates with lumbar arthroplasty that did not reach clinical significance. There was no statistically significant difference between the groups in clinic outcome measures. There was a statistically significant level of improvement from baseline and last follow-up in ODI and VAS (Back and Leg) in both treatment groups. Lumbar facet replacement and lumbar interbody fusion both appear to be viable options for treatment of one-level lumbar stenosis due to degenerative spondylolisthesis. Continued enrollment with long-term follow-up is required to validate these early findings as well as to evaluate for any differences between rigid and dynamic stabilization on adjacent level disease. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.