Adjustment of Leg Length Discrepancy in THA Using CT-Free Navigation System without the Use of a Femoral Tracker

INTRODUCTION: Since 2005, we have used OrthoPilot (B. Braun Aesculap, Tuttlingen, Germany) CT-free navigation system for improved and consistent acetabular cup orientation in THA. In order to achieve success of the THA, adjustment of leg length discrepancy is another important factor influencing the operative result. Currently, when the navigation system is utilized for this adjustment, installation of an additional device (tracker or clamp) for the femur is required. Fixation of such measurement device to the femur is associated with additional surgical invasion and contradicts the current trend of minimally invasive surgery (MIS). To solve this problem, a new software “OrthoPilot THA plus” has been developed to eliminate the need for a tracker fixation to the femur in the intraoperative leg length adjustment. In this study, we analyzed the accuracy of this leg length adjustment system by comparing the intraoperative data and the postoperative data obtained from the radiological measurement.