Determination of Cutting Angle for Patient-Specific Replacement of Knee Joint Based on Mechanical Alignment

The need for total knee arthroplasty (TKA) has grown significantly in recent years. The cutting angle in TKA plays a major role in the functionality and life expectancy of the knee implant components. This study aims to personalize the femur bone cutting angle selection for implant placement. This procedure ensures that the resulting mechanical alignment is the most suitable while minimizing the force transmission distance from the center of the knee. The loading conditions assume the challenging scenario of a person landing from a jump. A 3D model of the bones and implant was created for femur cutting angles ranging from 5° to 10° under these loading conditions. The model was then evaluated through finite element analysis. The results were used to determine the shortest force transmission distance from the center of the knee and lower applied stresses on the femur, tibia, and all implant components. The selected cutting angle was found to be 7° for the case of the analyzed model, resulting in a minimum force transmission distance of 2.48 mm from the center of the knee.