Abstract
The aim of this study was to investigate the biomechanical effects of stem extension
with a medial tibial bone defect in primary total knee arthroplasty (TKA) on load
distribution and stress in the proximal tibia using finite element (FE) analysis.
FE simulations were performed on the tibia bone to evaluate the stress and strain
on the tibia bone and bone cement. This was done to investigate the stress shielding
effect, stability of the tibia plate, and the biomechanical effects in TKA models
with various medial defects and different stem length models.
The results demonstrated that in the bone defect model, the longer the stem, the lower
the average von Mises stress on the cortical and trabecular bones. In particular,
as the bone defect increased, the average von Mises stress on cortical and trabecular
bones increased. The average increase in stress according to the size of the bone
defect was smaller in the long stem than in the short stem. The maximal principal
strain on the trabecular bone occurred mainly at the contact point on the distal end
of the stem of the tibial implant. When a short stem was applied, the maximal principal
strain on the trabecular bone was approximately 8% and 20% smaller than when a long
stem was applied or when no stem was applied, respectively.
The findings suggest that a short stem extension of the tibial component could help
achieve excellent biomechanical results when performing TKA with a medial tibial bone
defect.
Keywords
stem extension - medial tibial bone defects - total knee arthroplasty - finite element
analysis
