Assessment of accuracy of an imageless hand-held robotic-assisted system in component positioning in total knee replacement: a prospective study

In recent years, robotic technology is becoming more pervasive in joint arthroplasty. The role of robotics in joint replacement surgery is to bring precision and accuracy in bone preparation, implant positioning and soft tissue balancing. However, there is yet to be a study conducted to determine the accuracy of bone preparation done by a new robotic system. The purpose of this study is to evaluate and report on the accuracy of bone cuts using imageless semiautonomous freehand robotic sculpting system, Navio (Smith & Nephew) based on the data provided by the robotic system. Between August 2018 and May 2019, a total of 62 patients were prospectively enrolled in this study. All surgeries were done by the senior author using a medial para-patellar approach and using a posterior stabilised implant (Anthem, Smith & Nephew Inc.). The study included 37 female patients and 25 male patients. The parameters assessed in this study were: (1) mechanical axis, (2) femoral coronal alignment, (3) femoral rotation, (4) femoral sagittal alignment, (5) tibial slope and (6) tibial coronal alignment using paired t test and root mean squared error (RMSE). The robotic system was accurate in achieving the bone cuts as planned in mechanical axis alignment ( p = 0.89, RMSE = 0.56), femoral coronal alignment ( p = 0.36, RMSE = 0.36), femoral sagittal alignment ( p = 0.10, RMSE = 0.44), femoral rotation ( p = 0.91, RMSE = 0.11), tibial coronal alignment ( p = 0.81, RMSE = 0.24) and tibial slope ( p = 0.30, RMSE = 0.37) with the maximum RMSE being 0.56. This study demonstrated that semi-autonomous hand-held robotic system, Navio (Smith & Nephew) for total knee arthroplasty produced accurate component positioning as per plan in all planes. The maximum RMSE was 0.56°.