A whole leg radiograph is not necessary for postoperative determination of the mechanical leg axis after total knee arthroplasty.

Background: Anteroposterior (AP) whole leg radiographs (WLR) in the standing position for assessment of the mechanical leg axis are generally performed preoperatively for the planning of total knee replacement (TKR) and postoperatively to assess the leg axis. The objective of the present study was to investigate whether, if preoperative WLR are available, postoperative AP standard knee radiographs in the standing position are sufficient for calculating the mechanical leg axis.

Methods: In the present prospective study, the mechanical and the anatomical leg axes were determined on the basis of WLR from 104 patients prior to implantation of a TKR and the difference was calculated.