Early Radiographic and Clinical Outcomes of Robotic-arm-assisted versus Conventional Total Knee Arthroplasty: A Multicenter Randomized Controlled Trial

Objective: A robotic system was recently introduced to improve prosthetic alignment during total knee arthroplasty (TKA). The purpose of this multicenter, prospective, randomized controlled trial (RCT) was to determine whether robotic-arm-assisted TKA improves clinical and radiological outcomes when compared to conventional TKA.

Methods: One hundred and thirty patients who underwent primary TKA were enrolled in this prospective, randomized controlled trial, which was conducted at three hospitals. Five patients were lost to follow-up 6 weeks after surgery. Therefore, 125 participants (63 in the intervention group and 62 in the control group) remained in the final analysis. The primary outcome was the rate at which the mechanical axis of the femur deviated by less than 3° from the mechanical axis of the tibia. This was evaluated by full-length weight-bearing X-rays of the lower limb 6 weeks postoperatively. Secondary outcomes included operation times, 6-week postoperative functional outcomes evaluated by the American Knee Society score (KSS) and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), short form-36 (SF-36) health survey results, and the occurrence of adverse events (AEs) and serious adverse events (SAEs).

Results: At 6 weeks postoperatively, we found that the rate of radiographic inliers was significantly higher in the intervention group (78.7% vs 51.6%; p = 0.00; 95% confidence interval, 10.9% to 43.2%). The operation was significantly longer in the intervention group than in the control group (119.5 vs 85.0 min; p = 0.00). There were no significant differences in the 6-week postoperative functional outcomes, SF-36, AEs, and SAEs between the two groups. There were no AEs or SAEs that were determined to be "positively related" to the robotic system.

Conclusion: Robotic-arm-assisted TKA is safe and effective, as demonstrated in this trial.