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Robotics and Navigation as Learning Tools for Fellows Training in Hip Arthroplasty

Introduction: The association between implant malpositioning and complications has been repeatedly demonstrated. Recently, technological advancements have allowed for more consistent implant placement. Beyond this obvious application, these technologies may also serve as a learning tool. Thus, the aim of this study was to evaluate the accuracy of fellows' estimation of implant positioning using a robotic system.

Methods: Data were prospectively collected for all patients undergoing total hip arthroplasty between September 2019 and December 2019. The fellow was blinded to the robotic system. Before reaming and broaching by the senior surgeon, the fellow was asked to place the reamer at 40° of cup inclination and 20° of version. The resulting values were recorded before the true measurements were revealed. A similar process was followed for femoral broaching.

Results: The mean difference between the estimated and actual cup inclination and version was 7.24° (P = 0.060) and 4.81° (P = 0.031), respectively. The mean difference in broach version was 7.00° (P = 0.159). Without the robotic system, 43.47% and 69.57% of patients would have had the cup placed outside of the safe zones described by Lewinnek and Callanan, respectively.

Conclusions: The estimated anteversion of the acetabular implant was found to be markedly different from its actual anteversion. A considerable portion of the cups would have been positioned outside of the Lewinnek and Callanan "safe zones" provided that the implants would have been manually positioned. The use of robotic or navigation systems may provide useful learning tools for fellows in training to understand their own inaccuracies in estimated implant position and hence refine their abilities.

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