Biomechanical comparison between metal block and cement-screw techniques for the treatment of tibial bone defects in total knee arthroplasty based on finite element analysis

BACKGROUND Managing bone defects is a critical aspect of total knee arthroplasty. In this study, we compared the metal block and cement-screw techniques for the treatment of Anderson Orthopaedic Research Institute type 2A tibial bone defects from the biomechanical standpoint. METHOD The metal block and cement-screw techniques were applied to finite element models of 5- and 10-mm tibial bone defects. Biomechanical compatibility was evaluated based on the stress distributions of the proximal tibia and tibial tray. The displacement of the tibial tray and maximum relative micromotion between the tibial stem and tibia were analyzed to assess the stability of the implant. RESULTS The maximum stress in both the proximal tibia and tibial tray was greater with the cement-screw technique than with the metal block technique. The stress of the proximal lateral tibia with the cement-screw technique was significantly larger than with the metal block technique (p < 0.05). For the 5-mm bone defect, the maximum relative micromotion was lower than the critical value of 150 μm. For the 10-mm defect, the maximum relative micromotion was 128 μm with the metal block technique and 155 μm with the cement-screw technique, with the latter exceeding the critical value. CONCLUSIONS The cement-screw technique showed superior biomechanical compatibility to the metal block technique and is more suitable for 5-mm bone defects. However, as it may reduce the fixation strength in 10-mm bone defects, the metal block technique is more appropriate in this case.