Biomechanical and tissue handling property comparison of decellularized and cryopreserved tibialis anterior tendons following extreme incubation and rehydration

Little is known regarding the biomechanical profiles and tissue handling properties of decellularized and cryopreserved human tibialis anterior tendons prepared as allografts for ACL reconstruction. This study compared allografts prepared using two extremes of the same cryoprotectant incubation and rehydration technique with a standardly prepared control group. Porcine tibiae with similar apparent BMD were randomly divided into three groups of ten specimens. Paired tendons were randomly divided into two experimental groups: Group 1 = 8 h incubation/15 min rehydration; Group 2 = 2 h incubation/1 h rehydration. Group 3 (control) consisted of ten standardly prepared tendons with 20 min rehydration. Tissue handling properties were graded during allograft preparation using a modified visual analog scale. Similar diameter allografts were fixed in matched diameter extraction drilled tibial tunnels with 35 mm long, 1 mm > tunnel diameter bioabsorbable interference screws. Potted constructs were mounted in a servo hydraulic device, pretensioned between 10–50 N at 0.1 Hz (10 cycles), and isometric pretensioned at 50 N for 1 min, prior to 500 submaximal loading cycles (50–250 N) at 0.5 Hz, and load to failure testing (20 mm/min). Constructs prepared under extreme conditions generally displayed comparable biomechanical properties to the control condition. Group 1 (8 h incubation/15 min rehydration)(−34 ± 35 ms) and Group 2 (2 h incubation/1 h rehydration) (−22 ± 38 ms) displayed smaller mean displacement-load peak phase timing differences over the initial ten cycles compared to Group 3 (control)(−42 ± 49 ms), P = 0.004, suggesting greater relative construct stiffness. Group 1 (8 h incubation/15 min rehydration) (234.9 ± 34 N/mm) and Group 2 (2 h incubation/1 h rehydration)(231.3 ± 43 N/mm) displayed lower construct stiffness during load to failure testing than Group 3 (control)(284.5 ± 25.2 N/mm), P = 0.003. Group 1 (8 h incubation/15 min rehydration) differed from Group 2 (2 h incubation/1 h rehydration) and Group 3 (control) for perceived tensile stiffness (2.4 ± 2.0 vs. 7.0 ± 0.5 and 7.9 ± 0.3, respectively), compressive resilience (1.7 ± 0.8 vs. 5.9 ± 1.0 and 7.8 ± 0.4, respectively), handling ease (2.8 ± 1.0 vs. 6.5 ± 0.5 and 7.0 ± 0.7, respectively), color (2.6 ± 0.8 vs. 4.7 ± 0.7 and 5.1 ± 0.3, respectively) and texture (4.0 ± 0.8 vs. 6.2 ± 0.8 and 6.8 ± 0.8, respectively) ( P