Robotic Arm Assisted Total Hip Replacement: an Assistant and a Mentor

Abstract

<p>Objectives: Acetabular cup placement is vital to minimizing dislocation and ensuring implant longevity in total hip arthroplasty(THA). Robotic arm assistance allows precise cup placement. This prospective study aimed to compare the accuracy of cup placement using manual technique verified by robotic software for surgeons in different phases of training.<br>Methods: This prospective study was performed in the first 25 consecutive robotic THA performed by a single surgeon using posterior approach. Three surgeon, fellow and resident, who were novel to robotic THA but had varying degrees of exposure to conventional THA completed the study. During trial, each of them were then asked to manually position an acetabular trial aiming to produce an inclination of 40 degrees and anteversion of 20 degrees, blinded and without robotic guidance. The measurements were recorded and compared for consistency and learning curve phenomenon.<br>Results: 75 manual trial cup positioning attempts were made by the surgical team in 25 consecutive robotic THA.. Manual cup positioning yielded a mean inclination of 40 degrees(sd= 6.98) while mean anteversion was only 16.2 degrees(sd=8.1) despite aiming for 20. Both the surgeon and fellows improved in accuracy beyond the learning curve. Intraoperative verification of cup position correlated strongly with preoperative planning in both inclination(r=0.67, p=0.0003) and anteversion(r=0.75, p=0.0002).<br>Conclusion: Manual acetabular cup positioning tends to produce small anteversion and robotic arm is an excellent teacher to improve accuracy. Robotic assistance also guarantees accurate cup position according to plan.<br></p>