title: Particle size influence in an impaction bone grafting model. Comparison of fresh-frozen and freeze-dried allografts.
abstract: BACKGROUND
  Impaction bone grafting with large particles is considered as mechanically superior to smaller morsels. Interest of freeze-dried irradiated bone for impaction bone grafting has been observed with small particles. Influence of bone process on other particle sizes still needed to be assessed.
  
  
  METHODS
  Twenty-four osteoarthrotic femoral heads were used to prepare fresh-frozen and freeze-dried irradiated cancellous bone. Each group was divided into four batches of different particle sizes, each batch containing 18 samples. The different particle sizes were obtained with a Retsch Cross Beater Mill SK 100, Noviomagus rotating bone mills with two sizes of rasps and a Luer bone rongeur. Bone grafts were impacted in a contained cylinder. Stiffness was monitored during impaction.
  
  
  RESULTS
  Freeze-dried irradiated grafts showed higher stiffness than fresh-frozen bone whatever the size of the particles. Large particles obtained with the rongeur and the large rasp from the Noviomagus bone mill were mechanically superior than small particles up to 30 impactions.
  
  
  CONCLUSIONS
  Large particles offer better mechanical performance as a greater magnitude of force would be required to deform and break the particles. Freeze-dried irradiated bone brittleness reduces this advantage after 30 impactions. Large particles embrittlement leads to similar mechanical results as small particles at higher impaction rate. This may account for partial collapse of the graft layer in clinical situation when impaction rate is lower. This model supports the use of small particles obtained with thin rasp bone mill when freeze-dried irradiated bone for impaction bone grafting and large particles obtained with the Rongeur when fresh-frozen bone is available.
authors: Orthopaedic Research Laboratory, Université Catholique de Louvain, Brussels, Belgium. cornu@orto.ucl.ac.be
authors: Olivier
authors: O
authors: Cornu
authors: Thomas
authors: T
authors: Schubert
authors: Xavier
authors: X
authors: Libouton
authors: Olivier
authors: O
authors: Manil
authors: Bernard
authors: B
authors: Godts
authors: John
authors: J
authors: Van Tomme
authors: Xavier
authors: X
authors: Banse
authors: Christian
authors: C
authors: Delloye
mesh_terms: D016025:Bone Transplantation / Q000379:methods*; D055119:Elastic Modulus / Q000502:physiology; D005270:Femur Head / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects / Q000637:transplantation*; D005612:Freeze Drying; D066298:In Vitro Techniques; D008954:Models, Biological; D010316:Particle Size; D013314:Stress, Mechanical; D020858:Tissue and Organ Harvesting / Q000379:methods*