Distal femoral resection at knee replacement — The effect of varying entry point and rotation on prosthesis positionGangadharan, Rajkumar; Deehan, David J; McCaskie, Andrew W
Malalignment may contribute to early prosthesis failure through point loading and premature polyethylene wear. Femoral resection requires for distal planar resection contingent upon correct rotation and coronal alignment. Using a standard model, we have examined the influence of differing femoral entry points and rotations upon final femoral component positioning. A graphical method and navigation system independently quantified the individual and combined impact of these variables, in 3 planes. Nine permutations were assessed with reference to neutral rotation and a central entry point. The graphical results were corroborated by the navigation analyses. We found that external rotation and a superolateral entry point introduced the greatest error in final component positioning. We have identified a safe envelope for femoral rod positioning and recommend that the rotational alignment is determined before distal bone resection.