Effects of a novel sterilization process on soft tissue mechanical properties for anterior cruciate ligament allografts

Abstract

Background: Allograft anterior cruciate ligament reconstruction provides benefits such as earlier return to activities and less pain, but concerns remain regarding potential infection and biomechanical stability.

Hypothesis: There is no difference in biomechanical properties of soft tissue allografts treated with the Biocleanse tissue sterilization process compared with irradiated and fresh-frozen allografts.

Study design: Controlled laboratory study.

Methods: Thirty-six tibialis anterior allografts were equally divided between Biocleanse, irradiated, and fresh-frozen groups. Grafts were measured for cross-sectional area and looped over a smooth rod with the free sutured ends of the graft fixed in custom clamps. Specimens were tensioned to 10 N for 2 minutes and then loaded between 50 and 300 N for 1000 cycles followed by a failure test. Data for creep (mm); stiffness (N/mm) at cycles 1, 10, 100, and 1000; failure load (N); and failure stress (MPa) were compared with a one-way analysis of variance (P < .05).

Results: There were no statistically significant differences in creep between groups. Sterilized groups (irradiated = 144.7 +/- 17.7 N/mm and Biocleanse = 146.5 +/- 28.2N/mm) were significantly stiffer during the first cycle than the fresh-frozen group (117.8 +/- 15.7 N/mm, P < .005) without statistically significant differences for subsequent cycles. There were no differences between groups for either failure load (fresh-frozen = 1665 +/- 291.3 N, irradiated = 1671.9 +/- 290.2 N, Biocleanse = 1651.6 +/- 377.4 N) or failure stress.

Conclusion: Data for "time-zero" physiologic stiffness and failure loads indicate that the Biocleanse process does not adversely affect the biomechanical properties of the allograft material.

Clinical relevance: This novel sterilization technique may provide surgeons with potential allograft material with similar biomechanical properties to native tissue.