title: Two-year clinical outcomes of a multicenter randomized controlled trial comparing two interspinous spacers for treatment of moderate lumbar spinal stenosis.
abstract: BACKGROUND
  Interspinous spacers are a minimally invasive surgical alternative for patients with lumbar spinal stenosis (LSS) unresponsive to conservative care. The purpose of this prospective, multicenter, randomized, controlled trial was to compare 2-year clinical outcomes in patients with moderate LSS treated with the Superion(®) (Experimental) or the X-Stop(®), a FDA-approved interspinous spacer (Control).
  
  
  METHODS
  A total of 250 patients with moderate LSS unresponsive to conservative care were randomly allocated to treatment with the Experimental (n = 123) or Control (n = 127) interspinous spacer and followed through 2 years post-treatment. Complication data were available for all patients and patient-reported outcomes were available for 192 patients (101 Experimental, 91 Control) at 2 years.
  
  
  RESULTS
  Zurich Claudication Questionnaire (ZCQ) Symptom Severity and Physical Function scores improved 34% to 36% in both groups through 2 years (all p < 0.001). Patient Satisfaction scores at 2 years were 1.8 ± 0.9 with Experimental and 1.6 ± 0.8 with Control. Axial pain decreased from 59 ± 26 mm at baseline to 21 ± 26 mm at 2 years with Experimental and from 55 ± 26 mm to 21 ± 25 mm with Control (both p < 0.001). Extremity pain decreased from 67 ± 24 mm to 14 ± 22 mm at 2 years with Experimental and from 63 ± 24 mm to 18 ± 23 mm with Control (both p < 0.001). Back function assessed with the Oswestry Disability Index similarly improved with Experimental (37 ± 12% to 18 ± 16%) and Control (39 ± 12% to 20 ± 16%) (both p < 0.001). Freedom from reoperation at the index level was 84% for Experimental and 83% for Control (log-rank: p = 0.38) at 2 years.
  
  
  CONCLUSIONS
  Both interspinous spacers effectively alleviated pain and improved back function to a similar degree through 2 years in patients with moderate LSS who were unresponsive to conservative care.
  
  
  BACKGROUND
  NCT00692276.
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: Larry E
authors.initials: LE
authors.lastname: Miller
authors.affiliation: The Jon Block Group, 2210 Jackson Street, Suite 401, San Francisco, CA 94115, USA. jonblock@jonblockgroup.com.
authors.forename: Jon E
authors.initials: JE
authors.lastname: Block
authors.forename: Fred H
authors.initials: FH
authors.lastname: Geisler
mesh_terms: D000368:Aged; D001416:Back Pain / Q000209:etiology / Q000517:prevention & control; D004185:Disability Evaluation; D004867:Equipment Design; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D019637:Orthopedic Procedures / Q000009:adverse effects / Q000295:instrumentation*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000209:etiology / Q000517:prevention & control; D017060:Patient Satisfaction; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011859:Radiography; D020127:Recovery of Function; D013130:Spinal Stenosis / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States