Method

Approval from the Ethics Committee at The University of New South Wales Sydney Australia was granted prior to commencement of this study. 50 patients who had undergone total knee replacement (Evolis, Medacta International) using CT-based patient specific instrumentation (MY KNEE Medacta International) were assessed postoperatively using a CT scan and a validated measurement technique. The mechanical axis of the limb in the coronal plane, the varus/valgus positioning of the femoral component, the varus/valgus positioning of the tibial component, the flexion/extension of the posterior flange of the femoral component and the posterior slope of the tibial base plate were recorded. These results were then compared to each patient's preoperative planning. The percentage of patients found to be within 3 degrees of planned alignment were calculated. This represents the most comprehensive prospective study to utilize CT assessment of postoperative alignment in patient specific instrumentation. All other studies, to our knowledge have utilized scanograms or scout images and not full CT protocol as performed in this study.