The accuracy of image-guided knee replacement based on computed tomography

Our study evaluated the accuracy of an image-guided total knee replacement system based on CT with regard to preparation of the femoral and tibial bone using nine limbs from five cadavers. The accuracy was assessed by direct measurement using an extramedullary alignment rod without radiographs. The mean angular errors of the femur and tibia, which represent angular gaps from the real mechanical axis in the coronal plane, were 0.3degrees and 1.1degrees respectively. The CT-based system, provided almost perfect alignment of the femoral component with less than 1degrees of error and excellent alignment with less than 3degrees of error for the tibial component. Our results suggest that standardisation of knee replacement by the use of this system will lead to improved long-term survival of total knee arthroplasty.