title: Freeze-dried irradiated bone brittleness improves compactness in an impaction bone grafting model.
abstract: BACKGROUND
  Defatted bone chips with or without freeze-drying and irradiation have mechanical advantages as compared to fresh-frozen controls in in vitro models of impaction. These improved results have been ascribed to replacement of viscous bone marrow by saline and embrittlement of the freeze-dried bone by irradiation.
  
  
  METHODS
  To determine which of these hypotheses is correct, we compared the development of stiffness and compactness of morselized bone graft that had been: 1) fat-reduced with saline, and 2) fresh-frozen, solvent-detergent defatted, 3) freeze-dried irradiated and 4) not irradiated. We used 12 osteoarthrotic femoral heads to prepare these four batches of morselized bone, and impacted 18 samples from each batch in a cylinder. The frozen bone grafts were tested after thawing at room temperature for 2 hours and the freeze-dried grafts were tested after 30 minutes of rehydration. We monitored the development of compactness and stiffness of the material during impaction.
  
  
  RESULTS
  The stiffness of the freeze-dried irradiated bone was greater than that of the other three series after 10, 50 and 150 impactions. The freeze-dried bone chips that were not irradiated and the chips defatted with saline alone were less stiff than the fresh-frozen control after 150 impactions.
  
  
  CONCLUSIONS
  The brittleness of freeze-dried irradiated bone, caused by loss of the capacity to absorb energy in a plastic way, increases the compactness and stiffness of the morselized grafts. Washing bone with saline alone or treating bone with solvent-detergent but no irradiation had no similar mechanical advantage and the bone did not impact better than fresh-frozen undefatted bone in our model.
authors.affiliation: Orthopaedic Research Laboratory, Université Catholique de Louvain, Brussels, Belgium. cornu@orto.ucl.ac.be
authors.forename: Olivier
authors.initials: O
authors.lastname: Cornu
authors.forename: Xavier
authors.initials: X
authors.lastname: Libouton
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Naets
authors.forename: Bernard
authors.initials: B
authors.lastname: Godts
authors.forename: John
authors.initials: J
authors.lastname: Van Tomme
authors.forename: Christian
authors.initials: C
authors.lastname: Delloye
authors.forename: Xavier
authors.initials: X
authors.lastname: Banse
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016025:Bone Transplantation / Q000379:methods*; D005260:Female; D005270:Femur Head / Q000528:radiation effects* / Q000637:transplantation*; D005612:Freeze Drying; D006801:Humans; D008297:Male; D008875:Middle Aged; D020858:Tissue and Organ Harvesting