title: [The efficacy and complication analysis of interspinous dynamic device (Wallis) in patients of degenerative lumbar disease].
abstract: OBJECTIVE
  To review degenerative lumbar disease treated with Wallis and the re-herniation cases after the implantation of Wallis, so as to evaluate the effect of the device.
  
  
  METHODS
  From January 2009 to June 2010, a retrospective analysis was done and 48 patients (30 males and 18 females) with an average age of 43 years (ranging from 17 to 69 years), who received stabilization of the segment using the Wallis device, were reviewed. The involved segments included: 4 cases at L(3-4), 38 cases at L(4-5), 6 cases at L(5)-S(1). Preoperative and postoperative visual analogue scales (VAS) and Oswestry disability index (ODI) were recorded to evaluate the clinical efficiency, imageology diversity was assessed by X-rays and MRI.
  
  
  RESULTS
  All cases received fenestration and the implantation of Wallis. No surgery related complications were recorded. There were 48 cases were followed up. The average follow-up period was (20 ± 4) months (12 - 30 months). The average ODI score dropped from 46 ± 10 to 24 ± 7 (t = 12.765, P < 0.05). The average VAS for back and leg pain dropped from 8.1 ± 1.6 to 2.1 ± 1.1(t = 21.881, P < 0.05). Six patients with recurrent lower back and leg pain were diagnosed by MRI, as recurrent herniation (6/48, 12.5%). All re-herniation occurred at L(4-5) level, between 2 and 13 months after the surgery. Three of the 6 patients underwent additional discectomy and fusion, others received conservative treatment.
  
  
  CONCLUSIONS
  Although existing problems such as recurrence after surgery, the clinical outcome of Wallis in treating protrusion of lumbar intervertebral disc and lumbar stenosis is satisfied in middle-early stage.
authors.affiliation: Department of Spinal Surgery, Peking University People's Hospital, Beijing, China. Liu_haiying@263.net
authors.forename: Hai-ying
authors.initials: HY
authors.lastname: Liu
authors.forename: Ai-qi
authors.initials: AQ
authors.lastname: Gu
authors.forename: Zhen-qi
authors.initials: ZQ
authors.lastname: Zhu
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013130:Spinal Stenosis / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult