title: Restoration of spinal alignment and disk mechanics following polyetheretherketone wafer kyphoplasty with StaXx FX.
abstract: OBJECTIVE
  EPFs sustained during VCFs degrade the disk's ability to develop IDP under load. This inability to develop pressure in combination with residual kyphotic deformity increases the risk for adjacent vertebral fractures. We tested the hypothesis that StaXx FX reduces kyphosis and endplate deformity following vertebral compression fracture, restoring disk mechanics.
  
  
  METHODS
  Eight thoracolumbar, 5-vertebrae segments were tested. A void was selectively created in the middle vertebra. The specimens were compressed until EPF and to a grade I-II VCF. PEEK wafer kyphoplasty was then performed. The specimens were then tested in flexion-extension (±6 Nm) under 400-N preload intact, after EPF, VCF, and kyphoplasty. Endplate deformity, kyphosis, and IDP adjacent to the fractured body were measured.
  
  
  RESULTS
  Vertebral body height at the point of maximal endplate deformity decreased after EPF and VCF and was partially corrected after StaXx FX, remaining less than intact (P = .047). Anterior vertebral height decreased after VCF (P = .002) and was partially restored with StaXx FX, remaining less than intact (P = .015). Vertebral kyphosis increased after VCF (P < .001) and reduced after StaXx FX, remaining greater than intact (P = .03). EPF reduced IDP in the affected disk in compression-flexion loading (P < .001), which was restored after StaXx FX (P = 1.0). IDP in the unaffected disk did not change during testing (P > .3).
  
  
  CONCLUSIONS
  StaXx FX reduced endplate deformity and kyphosis, and significantly increased anterior height following VCF. Although height and kyphosis were not fully corrected, the disk's ability to pressurize under load was restored.
authors.affiliation: Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, Illinois, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Renner
authors.forename: P P
authors.initials: PP
authors.lastname: Tsitsopoulos
authors.forename: A T
authors.initials: AT
authors.lastname: Dimitriadis
authors.forename: L I
authors.initials: LI
authors.lastname: Voronov
authors.forename: R M
authors.initials: RM
authors.lastname: Havey
authors.forename: G
authors.initials: G
authors.lastname: Carandang
authors.forename: B
authors.initials: B
authors.lastname: McIntosh
authors.forename: C
authors.initials: C
authors.lastname: Carson
authors.forename: D
authors.initials: D
authors.lastname: Ty
authors.forename: J G
authors.initials: JG
authors.lastname: Ringelstein
authors.forename: A G
authors.initials: AG
authors.lastname: Patwardhan
mesh_terms: D000368:Aged; D001577:Benzophenones; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena / Q000502:physiology; D002102:Cadaver; D005260:Female; D050815:Fractures, Compression / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D007403:Intervertebral Disc / Q000502:physiology / Q000601:surgery*; D007659:Ketones; D058498:Kyphoplasty / Q000295:instrumentation / Q000379:methods*; D007738:Kyphosis / Q000503:physiopathology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000502:physiology / Q000601:surgery*; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D011092:Polyethylene Glycols; D011108:Polymers; D016059:Range of Motion, Articular / Q000502:physiology; D016103:Spinal Fractures / Q000503:physiopathology / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000502:physiology / Q000601:surgery*
chemical_list: D001577:Benzophenones; D001672:Biocompatible Materials; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols