64 slice multidetector scanner

All patients received a CT-scan (64-slice multidetector scanner, Siemens^® Sensation, Munich, Germany) according to the manufacturer’s protocol 8 weeks before surgery, on which the FMA, TMA and HKA angles were measured (Knee-Plan^® software, Symbios, Yverdon les bains, Switzerland) to an accuracy of 1° [15 (link)]. Three-dimensional (3D) models enabled to correct for cases with bony wear by referring to the non-worn areas and to estimate the native pre-arthritic angles [11 (link)]. The Origin® prosthesis is CE-marked and its design is based on a 3D analysis of bony anatomy, arthritic deformities and native limb alignment, as captured by the preoperative CT-scans. The femoral component reproduced the contours, sagittal radii of curvature and joint line obliquity of the native femur. The tibial baseplate reproduced the contours of the native tibial plateau, and the polyethylene insert had up to 2 mm difference in thickness between the medial and lateral compartments. Manufacturing of the femoral component was based on a conventional Cobalt–Chromium casting process, followed by machining and polishing, whereas the tibial baseplate was machined from Titanium alloy. Single-use patient-specific cutting guides were manufactured from polyamide using additive manufacturing technology.