Accuracies of bone resection, implant position, and limb alignment in robotic-arm-assisted total knee arthroplasty: a prospective single-centre study

Objective This study assessed the accuracy of robotic-arm-assisted total knee arthroplasty (RATKA) for bone resection, component size prediction, implant placement, and limb alignment. Methods This prospective cohort study included 36 patients. All procedures were performed by a single experienced surgeon, using an identical approach and implant designs. The MAKO RIO Robotic Interactive Orthopaedic Arm (Stryker, Mahwah, NJ, USA) system was used. The actual bone resection, implant placement, component size, and postoperative mechanical alignment were recorded, then compared with the preoperative plan. Results The mean absolute differences from the plan for the distal (medial and lateral) and posterior (medial and lateral) femoral cuts were 0.39 mm (0.62), 0.49 mm (0.70), 0.62 mm (0.79), and 0.65 mm (0.81), respectively, with 0.57 degrees (0.65) varus. The mean absolute differences in the medial and lateral tibial cuts were 0.56 mm (0.75) and 0.58 mm (0.76), with 0.48 degrees (0.16) varus and 0.54 degrees (0.25) anterior/posterior slope. Of 192 bone resections, 176 (91.7%) were within <= 1 mm of the preoperative plan. The accuracies of femoral and tibial component size prediction were 100% and 97.22%, respectively. The mean absolute difference in final limb coronal alignment was 0.92 degrees (0.65). Of the alignments, 18 (75.0%) were within <= 1.00 degrees of the plan, and 100% were within <= 3.00 degrees of the plan. Conclusion RATKA could accurately predict the component size and execute a preoperative plan to achieve precise bone resection, and implant placement, thereby reducing alignment outliers.