ABSTRACT
The purpose of this study was to examine the biomechanical effects of bone-patellar
tendon-bone (BPTB) grafts subject to repeat freeze-thaw cycles in a cyclic loading
model. We hypothesized that repeat freeze-thaw cycles have deleterious effects on
the tensile properties of BPTB grafts.
Thirty BPTB composite grafts were harvested from porcine knee specimens. Tendons were
randomized into 3 groups: fresh, 1 freeze-thaw cycle (—80°C), or 2 freeze-thaw cycles.
The grafts were cyclically loaded to simulate the forces on the anterior cruciate
ligament during walking and running, prior to single cycle load-to-failure testing.
All tendon failures were mid-substance and occurred during the single cycle load-to-failure
testing. There was no statistically significant difference in ultimate stress or strain
between the groups. Repeat freeze-thaw cycles do not have deleterious effects on the
tensile properties of BPTB grafts in a cyclic loading model. Potential influence on
biologic graft healing or integration remains unknown.
