The Effects of Biomechanical Loading on the Tibial Insert After Primary Total Knee Arthroplasty: A Systematic Review

Background/Objectives: Total knee arthroplasty (TKA) is the gold-standard treatment for advanced knee arthritis, offering pain relief and improved joint function. However, tibial component malalignment, malrotation, and improper biomechanical loading remain critical factors contributing to implant failure, instability, and revision surgeries. This review systematically examines the impact of biomechanical loading on the tibial insert following primary TKA, with a focus on alignment, posterior tibial slope (PTS), and load distribution. Methods: A systematic literature search was conducted across the PubMed, Google Scholar, and Web of Science databases following the PRISMA guidelines. Studies investigating the effects of tibial component alignment, varus/valgus deviations, PTS, and load distribution on tibial inserts post-TKA were included. Seven studies meeting the inclusion criteria were analyzed and described narratively. Results: The reviewed studies highlighted that varus and valgus malalignment significantly alter tibiofemoral contact pressures and ligament strains, increasing the risk of aseptic loosening and implant failure. Excessive PTS was associated with posterior femoral translation, altered ligament tension, and increased contact stresses on polyethylene (PE) inserts. Kinematically aligned TKA demonstrated reduced tibial force imbalances and improved functional outcomes compared to mechanically aligned TKA. Computational and cadaveric studies revealed that even minor malalignments (e.g., 3° varus or valgus) can cause significant biomechanical changes. Conclusions: Biomechanical loading on tibial inserts after primary TKA is highly sensitive to the alignment and PTS. Optimal alignment and controlled biomechanical forces are essential. Kinematically aligned TKA has shown promising effects, preventing aseptic loosening and ensuring long-term implant survival. Further in vivo studies are needed to validate these findings and optimize surgical techniques.