A Comparative Biomechanical Analysis of Two Dissimilar Fixation Constructs for Posterolateral Tibial Plateau Fractures

Background: The management of posterolateral tibial plateau fractures is mainly done by stable fixation which facilitates early mobility. Anterolateral locking plate (ALP) fixation and posterolateral locking plate (PLP) fixation are two commonly used fixation methods in clinical. This investigation’s aim was to examine the posterolateral tibial plateau biomechanical properties via arithmetical modeling and to quantify their effects on the fracture reconstruction. Methods: Two different 3D posterolateral tibial plateau fracture finite element models with the ALP and PLP fixation were created. The daily life axial compressive load on a typical adult knee was simulated using diversified axial forces (250N 500N 750N and 1000N). The comparable maps of displacement, stress and relative displacement were analyzed and quantified along the fracture lines. Results: The comparable Von Mises Stress (EVMS) stresses and comparable displacement changes in the fixations were elevated and associated with axial force. However, under the same axial force, the EVMS of the PLP fixation system is smaller than that of the ALP fixation system. The concentration region of stress in two fixation systems is also different, which appears at point C in ALP fixation system and point A in PLP fixation system respectively. Under the same axial force, the displacement changes of the A-B-C-D point on ALP fixation system is larger than that on PLP fixation system, but there is no significant difference in equivalent strain at each point. Conclusions: The computed results of stress of the fracture models show that the posterolateral locking plate (PLP) fixation system can provided a better biomechanical stability than the anterolateral locking plate (ALP) fixation system in treatment of posterolateral tibia fracture although their internal stress distribution was differed. However, if the equivalent displacement is also taken into account, the ALP and PLP fixation system had similar ability to resistant deformation.