Decompression and Dynamic Sagittal Tether Stabilization for Degenerative Spondylolisthesis: Primary Outcomes of a Multicenter FDA IDE Trial.

STUDY DESIGN: Multicenter, concurrently controlled Food and Drug Administration Investigational Device Exemption trial. OBJECTIVE: To test the hypothesis that decompression combined with a dynamic sagittal tether (D+DST) was a safe and effective noninferior alternative to decompression and transforaminal lumbar interbody fusion (D+TLIF) for patients with degenerative spondylolisthesis (DS) and stenosis. SUMMARY OF BACKGROUND DATA: Instability leading to symptom recurrence in patients undergoing decompression alone for DS is a concern, resulting in many patients receiving decompression and fusion. An alternative was developed incorporating decompression with stabilization using a dynamic sagittal tether to restore flexion stability and facet joint engagement, reducing segmental translation. METHODS: Patients with Grade I DS+stenosis amenable to decompression were recruited. Outcomes included composite clinical success (CCS), leg/hip and back pain, Oswestry Disability Index (ODI), reoperations, and radiographic measures. CCS was defined as: successful implantation, no reoperation at index or adjacent levels, minimum 15-point ODI improvement, no device failure, and no neurologic decline unless attributable to unrelated cause. A propensity score (PS) model was developed using 25 preoperative covariates to achieve balance and control for bias. RESULTS: 287 patients were PS-selected (140 D+DST; 147 TLIF). D+DST demonstrated significantly lower operative time, blood loss, and hospital stay. CCS rates were 78.8% with D+DST and 61.2% with D+TLIF, with a PS-adjusted difference of +10.4% favoring D+DST, meeting the primary noninferiority endpoint. Leg/hip pain, back pain, and ODI scores significantly reduced in both groups. Angular motion and segmental translation were both reduced 24% after D+DST and by 68% and 77%, respectively, after D+TLIF. Angular and translational motion at the supradjacent level were significantly greater after D+TLIF, and statistically unchanged following D+DST. Index or adjacent level reoperation rates were 7.2% after D+DST and 9.8% after D+TLIF. CONCLUSIONS: D+DST was noninferior to D+TLIF at 2 years, supporting its effectiveness in treating Grade I DS+stenosis.