title: A biomechanical analysis of bone-patellar tendon-bone grafts after repeat freeze-thaw cycles in a cyclic loading model.
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 degrees 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.
authors.affiliation: Division of Sports Medicine, Department of Orthopedic Surgery, Rush University Medical Center, Rush Medical College, Chicago, IL 60612, USA.
authors.forename: Gregory H
authors.initials: GH
authors.lastname: Lee
authors.forename: Ashwin
authors.initials: A
authors.lastname: Kumar
authors.forename: Eric
authors.initials: E
authors.lastname: Berkson
authors.forename: Nikhil
authors.initials: N
authors.lastname: Verma
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Bach
authors.forename: Nadim
authors.initials: N
authors.lastname: Hallab
mesh_terms: D000465:Algorithms; D000818:Animals; D016118:Anterior Cruciate Ligament / Q000637:transplantation; D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D001696:Biomechanical Phenomena; D050376:Bone-Patellar Tendon-Bone Grafting / Q000379:methods*; D004548:Elasticity; D005615:Freezing; D007719:Knee Joint / Q000601:surgery; D023421:Models, Animal; D017847:Patellar Ligament / Q000601:surgery / Q000637:transplantation; D011897:Random Allocation; D034421:Sus scrofa; D013552:Swine; D013718:Tensile Strength