title: [Cement augmentation on the spine : Biomechanical considerations].
abstract: BACKGROUND
  Vertebral compression fractures are the most common osteoporotic fractures. Since the introduction of vertebroplasty and screw augmentation, the management of osteoporotic fractures has changed significantly.
  
  
  OBJECTIVE
  The biomechanical characteristics of the risk of adjacent fractures and novel treatment modalities for osteoporotic vertebral fractures, including pure cement augmentation by vertebroplasty, and cement augmentation of screws for posterior instrumentation, are explored.
  
  
  METHODS
  Eighteen human osteoporotic lumbar spines (L1-5) adjacent to vertebral bodies after vertebroplasty were tested in a servo-hydraulic machine. As augmentation compounds we used standard cement and a modified low-strength cement. Different anchoring pedicle screws were tested with and without cement augmentation in another cohort of human specimens with a simple pull-out test and a fatigue test that better reflects physiological conditions.
  
  
  RESULTS
  Cement augmentation in the osteoporotic spine leads to greater biomechanical stability. However, change in vertebral stiffness resulted in alterations with the risk of adjacent fractures. By using a less firm cement compound, the risk of adjacent fractures is significantly reduced. Both screw augmentation techniques resulted in a significant increase in the withdrawal force compared with the group without cement. Augmentation using perforated screws showed the highest stability in the fatigue test.
  
  
  CONCLUSIONS
  The augmentation of cement leads to a significant change in the biomechanical properties. Differences in the stability of adjacent vertebral bodies increase the risk of adjacent fractures, which could be mitigated by a modified cement compound with reduced strength. Screws that were specifically designed for cement application displayed greatest stability in the fatigue test.
authors.affiliation: Abteilung für Unfall-, Hand- und Wiederherstellungschirurgie, Universitätsklinikum Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Deutschland.
authors.forename: J P
authors.initials: JP
authors.lastname: Kolb
authors.affiliation: Abteilung für Unfall-, Hand- und Wiederherstellungschirurgie, Universitätsklinikum Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Deutschland.
authors.forename: L
authors.initials: L
authors.lastname: Weiser
authors.affiliation: Institut für Biomechanik, Technische Universität Hamburg Harburg, Denickestrasse 15, 21073, Hamburg, Deutschland.
authors.forename: R A
authors.initials: RA
authors.lastname: Kueny
authors.affiliation: Institut für Biomechanik, Technische Universität Hamburg Harburg, Denickestrasse 15, 21073, Hamburg, Deutschland.
authors.forename: G
authors.initials: G
authors.lastname: Huber
authors.affiliation: Abteilung für Unfall-, Hand- und Wiederherstellungschirurgie, Universitätsklinikum Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Deutschland.
authors.forename: J M
authors.initials: JM
authors.lastname: Rueger
authors.affiliation: Abteilung für Unfall-, Hand- und Wiederherstellungschirurgie, Zentrum für Operative Medizin, Klinik für Unfall-, Hand- und Wiederherstellungschirurgie, Universitätsklinikum Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Deutschland. wlehmann@uke.de.
authors.forename: W
authors.initials: W
authors.lastname: Lehmann
mesh_terms: D000368:Aged; D001843:Bone Cements / Q000627:therapeutic use*; D001863:Bone Screws; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D017276:Friction; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D008297:Male; D058866:Osteoporotic Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D011859:Radiography; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical; D016896:Treatment Outcome; D054854:Vertebroplasty / Q000295:instrumentation* / Q000379:methods
chemical_list: D001843:Bone Cements
keywords: Bone cements; Compression fractures; Osteoporosis; Vertebroplasty; pedicle screws