title: The in vitro stabilising effect of polyetheretherketone cages versus a titanium cage of similar design for anterior lumbar interbody fusion.
abstract: This biomechanical study was performed to test the primary segmental in vitro stabilising effect of a standard and large footprint radiolucent poly-ether-ether-ketone (PEEK) box cage versus a titanium box cage for anterior lumbar interbody fusion. Eighteen L2-L3 and sixteen L4-L5 cadaveric motion segments were divided into three groups and received a titanium cage or a radiolucent PEEK cage with standard or large footprint. All specimens were tested in three testing conditions: intact, stand-alone anterior cage and finally with supplemental translaminar screw fixation. Full range of motion and neutral zone measurements were determined and anterior cage pull out force was tested. The titanium design was significantly more effective in reducing the range of motion only in axial rotation. The larger footprint radiolucent cage did not increase stability as compared to the standard footprint. The titanium cage pull out force was significantly (P=0.0002) higher compared to both radiolucent cage constructs.
  
  
  CONCLUSIONS
  Supplemental posterior fixation is strongly recommended to increase initial stability of any anterior interbody fusion cage construct. Although the biomechanical stability necessary to achieve spinal fusion is not defined, the radiolucent designs tested in this study, with a standard footprint as well as with a larger footprint, may be insufficiently stabilised with translaminar screws as compared to the titanium implant. Supplemental pedicle screw fixation may be required to obtain adequate stabilisation in the clinical setting.
authors.affiliation: Institute for Spine Surgery and Applied Research, PO Box 9011, 6500, Nijmegen, The Netherlands. m.spruit@maartenskliniek.nl
authors.forename: M
authors.initials: M
authors.lastname: Spruit
authors.forename: R G
authors.initials: RG
authors.lastname: Falk
authors.forename: L
authors.initials: L
authors.lastname: Beckmann
authors.forename: T
authors.initials: T
authors.lastname: Steffen
authors.forename: R M
authors.initials: RM
authors.lastname: Castelein
mesh_terms: D001577:Benzophenones; D002102:Cadaver; D005260:Female; D006801:Humans; D020007:Implants, Experimental; D016268:Internal Fixators; D007659:Ketones; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery*; D008297:Male; D008422:Materials Testing; D011092:Polyethylene Glycols; D011108:Polymers; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical; D014025:Titanium
chemical_list: D001577:Benzophenones; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D014025:Titanium