title: Implant survival analysis and failure modes of the X-Stop interspinous distraction device.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To review the clinical outcome, implant survivorship and reasons for failure after X-Stop implantation.
  
  
  BACKGROUND
  Conflicting data exist concerning clinical outcome of the X-Stop interspinous spacer and little information is being published about implant survivorship and the need for revision surgery.
  
  
  METHODS
  This retrospective review evaluated 46 patients who underwent implantation of the X-Stop interspinous spacer for the treatment of neurogenic claudication. After a mean follow-up of 40 months, pain levels, 36-Item Short Form Health Survey (SF-36), Oswestry Disability Index (ODI), and the need for subsequent surgery were assessed and a Kaplan-Meier survivorship analysis was performed.
  
  
  RESULTS
  Within the follow-up period, the revision rate was found to be 30.4%. Lack of improvement at 6-week follow-up correlated well with subsequent revision surgery, which predominantly took place within 12 months after the index surgery. In patients who did not need to undergo revision surgery, clinical outcome parameters improved significantly. Kaplan-Meier survivorship analysis predicted an implant survival probability of 0.68 at 48 months postoperatively.
  
  
  CONCLUSIONS
  Clinical outcome after X-Stop implantation might be considerably less favorable than when it was being published previously. Patient selection might be a reason for early revision surgery. More criteria for better X-Stop indications might be needed.
authors.affiliation: From the Orthopaedic Hospital Speising, Spine Center, Speisingerstrasse, Vienna, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tuschel
authors.forename: Albert
authors.initials: A
authors.lastname: Chavanne
authors.forename: Claudia
authors.initials: C
authors.lastname: Eder
authors.forename: Michael
authors.initials: M
authors.lastname: Meissl
authors.forename: Philipp
authors.initials: P
authors.lastname: Becker
authors.forename: Michael
authors.initials: M
authors.lastname: Ogon
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007383:Intermittent Claudication / Q000209:etiology / Q000601:surgery*; D053208:Kaplan-Meier Estimate; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000209:etiology / Q000601:surgery*; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods; D012189:Retrospective Studies; D013130:Spinal Stenosis / Q000150:complications / Q000601:surgery*; D016896:Treatment Outcome