Initial Perioperative, Work Status, Activity and Safety Outcomes after Decompression and Dynamic Sagittal Tether Stabilization versus Transforaminal Lumbar Interbody Fusion for Degenerative Spondylolisthesis: Interim Results from an FDA IDE Trial.

William F. Lavelle1, Rick C. Sasso2, Alan T. Villavicencio3, Kee D. Kim4, Reginald J. Davis5, Louis C. Fielding6, Todd F. Alamin6, 7, *, Greg Maislin8, 10, Sigita Burneikiene2, 9, William C Welch10
1 SUNY Upstate Medical University, Syracuse, NY, USA
2 Indiana Spine Group, Carmel, IN, USA
3 Boulder Neurosurgical and Spine Associates at BCH, Boulder, CO, USA
4 University of California Davis, Sacramento, CA USA
5 The BioSpine Institute, Tampa, FL, USA
6 Empirical Spine, San Carlos, CA, USA
7 Stanford School of Medicine, Stanford, CA, USA
8 Biomedical Statistical Consulting, Philadelphia, PA, USA
9 Justin Parker Neurological Institute, Boulder, CO, USA
10 University of Pennsylvania, Philadelphia, PA, USA

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Creative Commons License
© 2023 Lavelle et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Stanford School of Medicine, Department of Orthopaedic Surgery, Redwood City, CA, USA; E-mail:



Symptomatic lumbar degenerative spondylolisthesis (DS) is most commonly treated with decompression and fusion to address both the neurologic symptoms and underlying instability. However, fusion has known drawbacks, including invasiveness, recovery time and cost. A novel dynamic sagittal tether (DST) was developed to provide anatomic segmental stabilization after decompression by augmenting the posterior tension band.


The objective of this study was to evaluate perioperative, work status and activity outcomes of decompression and DST stabilization (D + DST) vs. decompression and fusion (D + TLIF) from an ongoing FDA IDE study.


Preoperative through 3-month outcomes and safety data from the IDE study (NCT03115983) are presented here. All patients had symptomatic Grade I DS with spinal stenosis, preoperative ODI≥35 and VAS leg/hip pain≥50. A propensity score (PS) model was utilized to control for inter-group differences in this parallel assignment (non-randomized) study. One hundred forty (140) patients had D + DST and 147 had D + TLIF. Perioperative characteristics, patient-reported outcomes, work status and activities of daily living (ADL) were analyzed with propensity score PS-adjusted difference and confidence intervals or chi-squared tests for multiple categorical variables. Kaplan-Meier survivorship analyses were performed for return-to-work and ADLs.


There were no significant PS-adjusted demographic, functional, disease or radiographic characteristic differences between groups preoperatively. The D + DST group had a PS-adjusted mean 70-minute shorter operative time, 183-ml less estimated blood loss and 2.3-day shorter hospital stay, with 66% of D + DST patients discharged the day of surgery and 88% discharged by the first postoperative day. At both the 6-week and 3-month intervals, more D + DST patients reported returning to work and ADLs. Both groups experienced significant reductions in leg/hip and back pain as well as disability 3-months postoperatively, while the D + DST group had significantly lower disability scores 6-weeks postoperatively. There were no significant differences in safety outcomes between the two groups, with 29 serious adverse events (SAEs) and 2 secondary surgeries (1.5%) in the D + DST group vs. 28 SAEs and 3 secondary surgeries (2.1%) in the D + TLIF group.


Compared to D + TLIF, the D + DST procedure was shorter, less invasive and had a faster discharge. Faster recovery, return to work and ADLs with lower disability at 6 weeks were noted in the D + DST group. If longer-term results are durable, the DST may represent a less invasive stabilization alternative after decompression compared to instrumented fusion.

Trial Registration Number: NCT03115983

Keywords: Degenerative spondylolisthesis, Motion preservation, Outpatient, ASC, Tether, Non-fusion, Lumbar.