Theoretical risk of anterior femoral cortex notching in total knee arthroplasty using a navigation system.

Two important requirements for navigation systems in total knee arthroplasty (TKA), perpendicular cut from the distal femoral condyle to the femoral mechanical axis and prevention of notching of the anterior femoral cortex, might be difficult to meet simultaneously. The potential risk of notching was investigated using three-dimensional (3D) computed tomography data of 50 entire lower extremities of 50 female Japanese candidates for TKA and a 3D template system. Navigation systems for TKA carry the potentially higher risk of notching of the anterior femoral cortex (34% to 51%) than conventional technique (11%) (P<0.001). More anterior setting of the reference point for navigation systems on the distal femur and more external setting of the femoral component were risk factors for notching (P<0.001).