title: Superion interspinous process spacer for intermittent neurogenic claudication secondary to moderate lumbar spinal stenosis: two-year results from a randomized controlled FDA-IDE pivotal trial.
abstract: METHODS
  Prospective, multicenter, randomized, controlled, investigational device exemption noninferiority trial.
  
  
  OBJECTIVE
  To determine 2-year outcomes in patients with intermittent neurogenic claudication secondary to moderate lumbar spinal stenosis (LSS) who were treated with the Superion interspinous process spacer.
  
  
  BACKGROUND
  Interspinous spacers are a less-invasive treatment alternative compared with surgical decompression for patients with LSS unresponsive to conservative care. High-quality comparative data with these devices are lacking.
  
  
  METHODS
  Patients presenting with intermittent neurogenic claudication secondary to moderate LSS who failed at least 6 months of nonsurgical management were randomly allocated to treatment with the Superion spacer or a control spacer (X-Stop) and followed for 2 years.
  
  
  RESULTS
  A total of 391 randomized patients were implanted with Superion (n = 190) or control (n = 201) spacers at 29 sites in the United States between August 2008 and December 2011. Implants were successfully implanted in 99.5% of patients with Superion and 99.0% of control patients. The primary composite endpoint of this study was met, which demonstrated that the Superion spacer was noninferior to the X-Stop spacer. Leg pain, the predominant patient complaint, decreased in severity by 70% during 2 years in each group. Most (77%) patients achieved leg pain clinical success (improvement ≥20 mm) at 2 years. Back pain clinical success (improvement ≥20 mm) was 68%, with no differences between groups. Oswestry Disability Index clinical success (≥15% point improvement) was achieved in 65% of patients. The rates of complications and reoperations were similar between groups.
  
  
  CONCLUSIONS
  The Superion interspinous process spacer relieves symptoms of intermittent neurogenic claudication secondary to moderate LSS in the majority of patients through 2 years.
  
  
  METHODS
  2.
authors.affiliation: *University of Colorado Hospital, Denver, CO †Department of Orthopaedic and Rehabilitation, Yale University School of Medicine, New Haven, CT ‡Performance Spine and Sports Physicians, P.C., Pottstown, PA §Texas Back Institute, Denton, TX ¶Spine Institute of Louisiana, Shreveport, LA ∥Stony Brook University, Stony Brook, NY **Miller Scientific Consulting, Inc., Asheville, NC ††The Jon Block Group, San Francisco, CA; and ‡‡McLaren Hospital, Petoskey, MI.
authors.forename: Vikas V
authors.initials: VV
authors.lastname: Patel
authors.forename: Peter G
authors.initials: PG
authors.lastname: Whang
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Haley
authors.forename: W Daniel
authors.initials: WD
authors.lastname: Bradley
authors.forename: Pierce D
authors.initials: PD
authors.lastname: Nunley
authors.forename: Raphael P
authors.initials: RP
authors.lastname: Davis
authors.forename: Larry E
authors.initials: LE
authors.lastname: Miller
authors.forename: Jon E
authors.initials: JE
authors.lastname: Block
authors.forename: Fred H
authors.initials: FH
authors.lastname: Geisler
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D007383:Intermittent Claudication / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*; D016268:Internal Fixators / Q000592:standards*; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants; D013130:Spinal Stenosis / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D035703:Therapies, Investigational; D014481:United States; D014486:United States Food and Drug Administration