Biomechanical analysis of allograft bone treated with a novel tissue sterilization process.

BACKGROUND CONTEXT: Several methods to sterilize allograft bone exist, including gamma irradiation and freeze-drying, which can alter the mechanical properties of the graft. Efforts are under way to develop a method for processing osseous allograft that maintains structural integrity. Herein is presented one such method.

PURPOSE: To analyze the mechanical properties, compared with nontreated controls, of a novel sterilization process for allograft cortical bone.

STUDY DESIGN/SETTING: A controlled biomechanical evaluation of allograft bone under various types of loading after a novel sterilization treatment.

PATIENT SAMPLE: Not applicable; basic science.

OUTCOME MEASURES: The load to failure was recorded for both the study and control groups, and statistical analysis of these results was performed. Significance level (alpha) and power (beta) were set to 0.05 and 0.90, respectively. Single-factor analysis of variance (ANOVA) was used to detect significant differences between the treated and untreated groups. A post-experimental power analysis was performed for each of the response variables.

METHODS: Cortical tibia and femur samples from seven cadaveric donors (mean age 68.7 years) were treated with Biocleanse and compared with untreated samples with regard to density and strength. All samples were loaded to failure under diametral and biaxial compression, shear, and three-point bending.

RESULTS: Statistical analysis was done on the density and failure stress for all modes of loading. ANOVA did not indicate a significant (p>.05) effect of treatment on the density except for the axial and biaxial specimens (p<.05). ANOVA analysis of failure stress demonstrated no significant differences (p>.05) between cortical bone treated with Biocleanse and untreated specimens under all four types of mechanical loading. Post-experimental power analysis revealed power to be greater than 0.9 for each test.

CONCLUSIONS: Sterilization of allograft bone with Biocleanse does not significantly alter the mechanical properties when compared with untreated samples. The effect of this sterilization process on the osteoconductive and osteoinductive properties of allograft bone must be determined.