Interfragmentary compression force and fixation stability of lateral tibial plateau fractures in normal and osteoporotic bones

Lateral platform collapse in fixations of lateral tibial plateau fractures (TPFs) using either double-lag screws fixation (DSF) or locking-plate fixation (LPF) is not rare. This study aimed to explore the effect of enhancing the interfragmentary compression force (IFCF) on fixation stability in lateral TPFs in normal and osteoporotic bones using finite element analysis. Finite element models of DSF in normal bone and LPF in normal and osteoporotic bones were established to simulate the fixations of lateral TPF. After model validation, axial compressive forces of 500, 1000, 1500, and 2500 N to the tibial plateau along with an IFCF of 0, 100, 200, and 300 N were applied. The maximum axial micromotion of the lateral fragment (MAM-LF), maximal translational micromotion of the lateral fragment (MTM-LF), peak von Mises stress (VMS), and peak equivalent elastic strain of the lateral fragment (EES-LF) were evaluated. The MAM-LF showed a decreasing trend as the IFCF increased in all models. For DSF models, the peak VMS of implants increased as the IFCF increased when the axial loads were 500 and 1000 N. The peak EES-LF decreased as the IFCF increased under axial loads of 1000, 1500, and 2500 N. For the normal and osteoporotic LPF models, the peak VMS of the implants decreased as the IFCF increased. Peak EES-LF decreased as IFCF increased. In conclusion, enhancing IFCF was beneficial in improving the fixation stability of lateral TPF. The optimal IFCF for DSF and LPF should be as high as reasonably feasible.