A biomechanical investigation of the anteromedial and posterolateral bands of the porcine anterior cruciate ligament

Abstract

The bipartite nature of the porcine anterior cruciate ligament has been documented, but its biomechanics have not been investigated. The need for such knowledge has recently been heightened with xenografting advances such as the introduction of the porcine patellar tendon as a human anterior cruciate ligament graft. The aim of this study is to compare the biomechanical properties of the intact anterior cruciate ligament with that of its two bands. 15 intact porcine anterior cruciate ligament–bone, 15 anteromedial band–bone, and 15 posterolateral band–bone complexes were prepared for tensile testing at 0.33 mm/s. Structural (load, deformation, stiffness, and energy absorbed) and material (stress, strain, modulus, and strain energy density) properties were analysed. Analysis of variance identified significantly higher ultimate load, stiffness, and energy absorbance in the intact porcine ligament when compared with its anteromedial band (p = 0.028). However, the intact ligament was only significantly higher in ultimate load when compared to its posterolateral band (p = 0.031). All ligament–bone complexes failed at similar deformations and strains, suggesting a strain-dependent failure mechanism. The intact porcine anterior cruciate ligament exhibited higher ultimate load, stiffness, and energy absorption than its two bands in isolation. The posterolateral band of the porcine anterior cruciate ligament constitutes a large proportion of the overall restraining function of the entire anterior cruciate ligament.