title: Biomechanical evaluation of the primary stability of pedicle screws after augmentation with an innovative bone stabilizing system.
abstract: BACKGROUND
  In today's aging population, diminished bone quality often affects the outcome of surgical treatment. This occurs especially when surgical implants must be fixed to bone, as it occurs when lumbar fusion is performed with pedicle screws. Besides Polymethylmethacrylate (PMMA) injection, several techniques have been developed to augment pedicle screws. The aim of the current study was to evaluate the primary stability of an innovative system (IlluminOss™) for the augmentation of pedicle screws in an experimental cadaveric setup. IlluminOss™ is an innovative technology featuring cement with similar biochemical characteristics to aluminum-free glass-polyalkenoate cement (GPC).
  
  
  METHODS
  IlluminOss™ was inserted transpedicularly via a balloon/catheter system in 40 human cadaveric lumbar vertebrae. For comparability, each vertebra was treated bilaterally with pedicle screws, augmented and non-augmented. The maximum failure load during pull out test was documented by a universal material testing machine.
  
  
  RESULTS
  The results showed significantly higher failure loads for the augmented pedicle screws (Median 555.0 ± 261.0 N, Min. 220.0 N, Max. 1,500.0 N), compared to the native screws (Median 325.0 ± 312.1 N, Min. 29.0 N, Max. 1,400.0 N).
  
  
  CONCLUSIONS
  Based on these data, we conclude the IlluminOss™ system can be used to augment primary screw stability regarding axial traction, compared to native screws. The IlluminOss™ monomer offers ease of control for use in biological tissues. In contrast to PMMA, no relevant heat is generated during the hardening process and there is no risk of embolism. Further studies are necessary to evaluate the usefulness of the IlluminOss™ system in the in vivo augmentation of pedicle screws in the future.
authors.affiliation: Centre for Orthopaedic and Trauma Surgery, University Medical Centre, Cologne, Germany, kilian.wegmann@uk-koeln.de.
authors.forename: K
authors.initials: K
authors.lastname: Wegmann
authors.forename: S
authors.initials: S
authors.lastname: Gick
authors.forename: C
authors.initials: C
authors.lastname: Heidemann
authors.forename: D
authors.initials: D
authors.lastname: Pennig
authors.forename: W F
authors.initials: WF
authors.lastname: Neiss
authors.forename: L P
authors.initials: LP
authors.lastname: Müller
authors.forename: P
authors.initials: P
authors.lastname: Eysel
authors.forename: R
authors.initials: R
authors.lastname: Sobottke
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001863:Bone Screws; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D019637:Orthopedic Procedures / Q000379:methods