Knee Phenotyping Prior To Total Knee Arthroplasty : Can We Eliminate The Need of Long Leg Radiographs With An Imageless Robotic System?

a) Background: Robot Assisted Total Knee Arthroplasty (RA TKA) has been shown to have increased accuracy and precision [1,2]. In recent years we have better understood the importance of  knee phenotypes based on bony morphology on the outcomes of TKA [3-5]. There are multiple different systems used to classify these knee phenotypes [6,7]. All of them use three main angle measurements: hip-knee-ankle angle (HKA), mechanical medial proximal tibial angle (mMPTA) and mechanical  lateral distal femoral angle (mLDFA). To measure these parameters, we need a standing long leg radiograph. However, this involves increased radiation exposure and can be time consuming.

b) Lacunae / Justification : Currently, there is no alternative to long leg radiographs for the measurement of these three angles. We have developed a way to measure these parameters intraoperatively and postoperative processing of the data by the engineering team. So far there is no study validating the use of this technique to measure these angles. By validating our technique, our aim is to eliminate the need of preoperative long leg radiographs to measure these parameters.