Biomechanical properties of bovine tendon xenografts treated with a modern processing method.

Xenograft tendons have been used in few human studies, with variable results. With the advent of novel tissue processing techniques, which may mitigate against an immune-mediated rejection response without adversely affecting mechanical properties, there may now be a clinical role for xenograft tendons, particularly in knee ligament reconstruction. We hypothesize that 'BioCleanse®' processed bovine extensor digitorum medialis (EDM) tendons exhibit favorable time-zero pre-implantation biomechanical characteristics when compared to both unprocessed bovine EDM tendons and BioCleanse® processed human cadaveric allograft tibialis anterior tendons. In this in vitro case controlled laboratory study, three groups of tendons underwent a 5-stage static loading test protocol: 15 BioCleanse bovine (BCB), 15 fresh frozen unprocessed bovine (FFB), and 12 BioCleanse human allograft (BCA) tendons. Cross-sectional area of the grafts was measured using an alginate molding technique, and tendons were mounted within an Instron 5565 Materials Testing System using cryogenic clamps. BCB tendons displayed a higher ultimate tensile stress (p<0.05), with equivalent ultimate failure load, creep, and modulus of elasticity when compared to the FFB tendons (p>0.05). BCB tendons had an equivalent cross-sectional area to the BCA tendons (p>0.05) whilst exhibiting a greater failure load, ultimate tensile stress, less creep and a higher modulus of elasticity (p<0.05). The BioCleanse process did not adversely affect the time-zero biomechanical properties of bovine xenograft EDM tendons. BioCleanse processed bovine xenograft EDM tendons exhibited superior biomechanical characteristics when compared with BioCleanse processed allograft tibialis anterior tendons. These findings support further investigation of xenograft tendons in orthopedic soft tissue reconstructive surgery.