Biomechanical comparison of figure-of-8 versus cylindrical tibial inlay constructs for arthroscopic posterior cruciate ligament reconstruction.

Abstract

To determine the biomechanical strength of Achilles tendon allografts with 2 different bone plug configurations as prepared for arthroscopic posterior cruciate ligament reconstruction when fixed as tibial inlay constructs. Nine matched pairs of cadaveric tibias were reconstructed by a standardized tibial inlay technique by use of either a cylindrical bone plug (12 mm in diameter) or a figure-of-8 bone plug (12 x 18 mm). Constructs were subjected to cyclic tensile loading followed by load to failure. The statistical analysis consisted of paired t tests with significance set at P < .05. No significant differences were found in yield load, ultimate load, stiffness, load at 5 mm, and total cyclic displacement between the groups. Although both constructs showed equivalent biomechanical properties, the tendons of the cylindrical bone plugs failed predominantly by shear off the bone compared with the figure-of-8 plugs, which failed by the sutures tearing through the tibial plateau. Tibial constructs with cylindrical and figure-of-8 bone plugs as prepared for use in arthroscopic posterior cruciate ligament reconstruction have comparable immediate biomechanical stability when fixed by a tibial inlay technique in a cadaveric model. Cylindrical and figure-of-8 bone plugs have comparable immediate biomechanical stability when fixed by a tibial inlay method, with the cylindrical technique being potentially technically easier to perform.