General Session: MIS-1
Presented by: P. Nunley - View Audio/Video Presentation (Members Only)
P. Nunley(1), V. Patel(2), D. Orndorff(3), J. Block(4), F. Geisler(5)
(1) Spine Institute of Louisiana, Shreveport, TX, United States
(2) University of Colorado, Denver, CO, United States
(3) Spine Colorado, Durango, CO, United States
(4) The Jon Block Group, San Francisco, CA, United States
(5) Rhausler, Inc, San Carlos, CA, United States
Purpose: Patients with moderate lumbar spinal stenosis that is unresponsive to conservative care now have a minimally invasive surgical option. Interspinous spacers do not need concomitant direct decompression to provide symptomatic relief from intermittent neurogenic claudication occurring during lumbar spine extension. The Superion® was approved by the US Food and Drug Administration (FDA) in 2015 after achieving the specified 2-year safety and effectiveness endpoints. Patients continue to be assessed for long outcomes in the FDA Investigational Device Exemption (IDE) clinical trial.
Methods: Four-year clinical outcomes are analyzed from patients enrolled in a randomized, controlled FDA IDE noninferiority trial comparing two commercially available spacers. Patients presenting with intermittent neurogenic claudication relieved with back flexion who failed at least 6 months of nonsurgical management were randomly allocated to treatment with the Superion® or a X-Stop™(Control). Outcomes included the Zurich Claudication Questionnaire (ZCQ) symptom severity (ss), physical function (pf) and patient satisfaction (ps) subdomains, Oswestry Disability Index (ODI), and leg and back pain by visual analog scale (VAS). A minimally important difference was defined a priori for patient reported outcome measures.
Results: Four years after the index procedure, patients demonstrated an improvement over baseline of 41%, 40%, 61%, 73% and 69% for ZCQss, ZCQpf, ODI, VAS leg and back pain, respectively. The patients reporting outcomes that exceeded the a priori-defined minimally important difference were 83% (74/89), 79% (70/89) and 87% (77/89) for ZCQss, ZCQpf, and ZCQps, 62% (55/89) for ODI, and 78% (67/86) and 66% (57/86) for VAS leg and back pain. Within-group effect sizes were all classified as very large (i.e., > 1.0): 1.49, 1.65, 1.46, 1.42 and 1.12 for ZCQss, ZCQpf, ODI, leg and back pain VAS, respectively.
Conclusions: Minimally-invasive implantation of the Superion® interspinous spacer continues to provide long-term, durable relief of intermittent neurogenic claudication symptoms for patients with moderate lumbar spinal stenosis.