title: Effect of a novel sterilization method on biomechanical properties of soft tissue allografts.
abstract: OBJECTIVE
  Evaluate allograft tissue commonly used in soft tissue reconstruction to determine whether stiffness and strength were significantly altered after grafts were treated with different sterilization methods. Unprocessed, irradiated, and grafts treated with supercritical CO2were compared.
  
  
  METHODS
  Thirty-eight anterior or posterior tibialis tendons were obtained from a tissue bank (Allograft Innovations, Gainesville, FL). Group I was unprocessed, group II was sterilized with gamma irradiation (20-28 kGy), and group III was sterilized with supercritical CO2. The grafts were pretensioned to 89 N for 300 s. Specimens were then loaded from 50 to 300 N at 0.5 Hz for 250 cycles before being loaded to failure at 50 mm/min. Dependent variables were compared between sterilization groups with one-way ANOVA (P < 0.05) and equivalence trial.
  
  
  RESULTS
  There was no significant difference in load to failure or failure stress among groups I, II, and III. Group III resulted in 27-36 % lower stiffness than group I and II. This difference was significant at 1, 10, 50, 100, and 250 cycles. There was no significant difference in stiffness between group I and group II.
  
  
  CONCLUSIONS
  The two sterilization methods tested in this study do not affect allograft strength. The supercritical CO2sterilization method resulted in significantly lower stiffness than unprocessed and irradiated allografts. However, the stiffness and strength of all groups tested were greater than that of published values of the native intact anterior cruciate ligament (ACL). This study provides previously unpublished mechanical test data on a new sterilization technique that will assist surgeons to decide which allograft to use in ACL reconstruction surgery.
  
  
  METHODS
  III.
authors.affiliation: University of Colorado, Denver, 13001 E. 17th Place, MSF432, Aurora, CO, 80045, USA. Todd.Baldini@UCDenver.edu.
authors.forename: T
authors.initials: T
authors.lastname: Baldini
authors.affiliation: University of Colorado, Denver, 13001 E. 17th Place, MSF432, Aurora, CO, 80045, USA.
authors.forename: K
authors.initials: K
authors.lastname: Caperton
authors.affiliation: Stryker Joint Preservation, Mahwah, NJ, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hawkins
authors.affiliation: University of Colorado, Denver, 13001 E. 17th Place, MSF432, Aurora, CO, 80045, USA.
authors.forename: E
authors.initials: E
authors.lastname: McCarty
mesh_terms: D000328:Adult; D064591:Allografts / Q000187:drug effects / Q000528:radiation effects*; D016118:Anterior Cruciate Ligament / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods; D001696:Biomechanical Phenomena / Q000187:drug effects / Q000528:radiation effects; D002245:Carbon Dioxide / Q000494:pharmacology*; D005260:Female; D005720:Gamma Rays; D006801:Humans; D008297:Male; D008875:Middle Aged; D013242:Sterilization / Q000379:methods*; D013314:Stress, Mechanical; D013710:Tendons / Q000187:drug effects / Q000528:radiation effects* / Q000637:transplantation; D014184:Transplantation, Homologous / Q000379:methods
chemical_list: D002245:Carbon Dioxide
keywords: Allograft; Anterior cruciate ligament; Biomechanics; Stiffness; Strength
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