title: The SNAP trial: a double blind multi-center randomized controlled trial of a silicon nitride versus a PEEK cage in transforaminal lumbar interbody fusion in patients with symptomatic degenerative lumbar disc disorders: study protocol.
abstract: BACKGROUND
  Polyetheretherketone (PEEK) cages have been widely used in the treatment of lumbar degenerative disc disorders, and show good clinical results. Still, complications such as subsidence and migration of the cage are frequently seen. A lack of osteointegration and fibrous tissues surrounding PEEK cages are held responsible. Ceramic implants made of silicon nitride show better biocompatible and osteoconductive qualities, and therefore are expected to lower complication rates and allow for better fusion.Purpose of this study is to show that fusion with the silicon nitride cage produces non-inferior results in outcome of the Roland Morris Disability Questionnaire at all follow-up time points as compared to the same procedure with PEEK cages.
  
  
  METHODS
  This study is designed as a double blind multi-center randomized controlled trial with repeated measures analysis. 100 patients (18-75 years) presenting with symptomatic lumbar degenerative disorders unresponsive to at least 6 months of conservative treatment are included. Patients will be randomly assigned to a PEEK cage or a silicon nitride cage, and will undergo a transforaminal lumbar interbody fusion with pedicle screw fixation. Primary outcome measure is the functional improvement measured by the Roland Morris Disability Questionnaire. Secondary outcome parameters are the VAS leg, VAS back, SF-36, Likert scale, neurological outcome and radiographic assessment of fusion. After 1 year the fusion rate will be measured by radiograms and CT. Follow-up will be continued for 2 years. Patients and clinical observers who will perform the follow-up visits will be blinded for type of cage used during follow-up. Analyses of radiograms and CT will be performed independently by two experienced radiologists.
  
  
  CONCLUSIONS
  In this study a PEEK cage will be compared with a silicon nitride cage in the treatment of symptomatic degenerative lumbar disc disorders. To our knowledge, this is the first randomized controlled trial in which the silicon nitride cage is compared with the PEEK cage in patients with symptomatic degenerative lumbar disc disorders.
  
  
  BACKGROUND
  NCT01557829.
authors.affiliation: Clinical Orthopaedic Research Center-midden Nederland (CORC-mN), Department of Orthopaedics, Diakonessenhuis, Utrecht/Zeist, The Netherlands. rkersten@diakhuis.nl.
authors.forename: Roel F M R
authors.initials: RF
authors.lastname: Kersten
authors.forename: Steven M
authors.initials: SM
authors.lastname: van Gaalen
authors.forename: Mark P
authors.initials: MP
authors.lastname: Arts
authors.forename: Kit C B
authors.initials: KC
authors.lastname: Roes
authors.forename: Arthur
authors.initials: A
authors.lastname: de Gast
authors.forename: Terry P
authors.initials: TP
authors.lastname: Corbin
authors.forename: F Cumhur
authors.initials: FC
authors.lastname: Öner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001577:Benzophenones; D001672:Biocompatible Materials; D002985:Clinical Protocols; D004311:Double-Blind Method; D005500:Follow-Up Studies; D006801:Humans; D016268:Internal Fixators; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D007659:Ketones; D017116:Low Back Pain / Q000209:etiology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008422:Materials Testing; D008875:Middle Aged; D018579:Patient Selection; D011092:Polyethylene Glycols; D011108:Polymers; D011183:Postoperative Complications / Q000209:etiology; D011859:Radiography; D012720:Severity of Illness Index; D017655:Silicon Compounds; D013123:Spinal Fusion / Q000295:instrumentation*; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D001577:Benzophenones; D001672:Biocompatible Materials; D007659:Ketones; D011108:Polymers; D017655:Silicon Compounds; C063834:polyetheretherketone; D011092:Polyethylene Glycols; C032734:silicon nitride