Computerized tomography assessment of femoral rotation in total knee arthroplasty - is there a target for navigation?

摘要

Introduction: Improvement of coronal alignment and reduction of outliner is meanwhile accepted as an advantage using navigation systems in total knee arthorplasty. The clear definition of the target of the mechanical axis can be achieved more accurate with navigation than with mechanical guides. Nevertheless rotational alignment of the components is also important for function of a knee endoprosthesis concerning stability and patellar tracking. Different axis and landmarks are used in conventional TKA to reach correct rotational alignment for the femoral component, depending on surgery technique and implant philosophy. Discussion which reference will result in best function is ongoing. The purposes of the present study were to analyze CT data from knee osteoarthritis patient characterize the variability of the different landmarks looking for a correlation to find a target value for navigated TKA. Methods: Using the VoXim~R software (IVS Solutions AG,Chemnitz, Germany) volumetric image data of 100 CT scans, done for CT based navigation with the Navitrack~R system (Orthosoft, Montreal, Canada) were measured. Following anatomical landmarks - posterior condyles, epicondyles, patellar grove and notch's roof - were defined in multiplanar and surface model in high precise reconstruction of lmm thin slice CTs. Axis and angles between the rotational axis were calculated automatically by the VoXim~R software. Mechanical axis were measured in long bone X-rays. Gender, age and OA-grade have been documented. Multiplanar control was given defining the landmarks in real time.