Role of Image-Free Robotic-Assisted Technology in Enhancing Accuracy of Implant Sizing for Total Knee Arthroplasty

Background The selection of properly sized implants is essential to achieve a well-balanced knee and favorable clinical outcomes following Total Knee Arthroplasty (TKA). There is limited evidence in the literature regarding the effectiveness of robotic-assisted technology (RA-TKA) without imaging in accurately predicting implant sizes. Our aim was to provide an evidence-based assessment of this technology's accuracy in selecting appropriate implant sizes during robotic-assisted, image-free TKA. Methods This study included 50 consecutive patients who underwent image-free robotic-assisted primary TKA for end-stage knee osteoarthritis, excluding those with prior knee surgeries or undergoing revision TKA. The same surgical team performed all procedures using a medial parapatellar approach and an image-free robotic system with a handheld saw. Initial data from the first 10 cases showed 100% accuracy in implant size prediction. We calculated a sample size of 28 patients to achieve a 90% reduction in prediction error. Femoral registration points were marked (femur center, Whiteside's line, distal medial condyle, distal lateral condyle, posterior medial condyle, posterior lateral condyle, and anterior femur cortex), and implant sizing suggested by the robotic system was verified against trial components by an independent observer. Efficacy was compared with historical controls using the Chi-square test, with significance set at p<0.05. Results The image-free robotic system had an accuracy of 92% (46 out of 50) in predicting the exact femoral component and 100% (50 out of 50) accuracy in predicting ±1 size femur component. Compared to the historical control, the accuracy of implant size prediction using the image-free robotic system was statistically significant (Chi-square test, p = 0.0005 and p = 0.0021, respectively). Conclusion The findings from this study highlight the effectiveness of image-free robotic-assisted technology in achieving precise implant sizing during primary TKA for end-stage osteoarthritis over traditional approaches. The system's improved accuracy in femoral sizing suggests a potential shift toward more reliable, data-driven implant selection that could minimize intraoperative adjustments. By promoting a standardized approach to component fitting, image-free robotics may help optimize surgical consistency, thereby supporting better long-term implant performance and patient satisfaction. These results encourage further exploration into image-free robotic systems as a valuable tool in advancing knee arthroplasty outcomes.