BJJ - 2026-04-07 - Journal Article; Randomized Controlled Trial; Multicenter Study
Robotic-assisted surgery and functional alignment in total knee arthroplasty: the RASKAL registry-nested 2 × 2 factorial randomized trial.
MacDessi SJ, Wernecke GC, Ghadirinejad K, Wood JA, Holder C, Lorimer M, Harris IA, and the RASKAL Study Group, Bastiras D, Boyle R, Chen DB, Du P, Fritsch B, Guzman M, Kirsh G, Limbers J, McEwen P, McMahon S, Mulford J, Oakey H, Penn D, Yu J
Topics
Key Takeaway
In a 2×2 factorial RCT of 303 TKA patients, robotic-assisted surgery and functional alignment each failed to improve KOOS-12 at two years compared to computer-assisted surgery and mechanical alignment (mean differences -2.8 and 0.3 points, respectively; both p>0.1).
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Summary
This registry-nested multicenter 2×2 factorial RCT randomized 303 TKA patients to robotic-assisted vs computer-assisted surgery and functional vs mechanical alignment, with KOOS-12 change as the primary outcome. Neither robotic-assisted surgery (mean difference -2.8, 95% CI -6.4 to 0.9) nor functional alignment (mean difference 0.3, 95% CI -3.4 to 4.0) demonstrated superiority at any timepoint through two years. Robotic-assisted surgery reduced operative time by 11.5 minutes and reduced PCL macroscopic soft-tissue injury, while functional alignment reduced soft-tissue release rates dramatically (8.1% vs 44.8%).
Key Limitation
Two-year follow-up is insufficient to determine whether the dramatically lower soft-tissue release rate with functional alignment (8.1% vs 44.8%) translates into differences in implant survivorship or late instability.
Original Abstract
AIMS
Robotic-assisted surgery and functional alignment are increasingly being adopted in total knee arthroplasty (TKA). This study assessed the individual and combined effectiveness of robotic-assisted surgery and functional alignment in improving outcomes in TKA, compared with computer-assisted surgery and mechanical alignment, respectively.
METHODS
A registry-nested, multicentre, blinded, 2 × 2 factorial, randomized trial was performed with 303 TKA patients randomized to robotic-assisted or computer-assisted surgery, and functional or mechanical alignment. The primary outcome was the between-group differences in postoperative change over two years in the mean Knee Injury and Osteoarthritis Outcome Score (KOOS-12). Secondary outcomes included knee-specific and general patient-reported outcome measures (PROMs), operative and functional outcomes, and adverse events. Primary modified intention-to-treat and secondary per-protocol analyses were performed.
RESULTS
There were no differences comparing robotic-assisted with computer-assisted surgery in KOOS-12 at three months, six months, one year, and two years (mean two-year difference -2.8; 95% CI -6.4 to 0.9; p = 0.137), and no differences comparing functional with mechanical alignment at three months, six months, one year, and two years (mean two-year difference 0.3 (95% CI -3.4 to 4.0); p = 0.867). No differences were found in Oxford Knee Score, Forgotten Joint Score, EuroQol five-dimension five-level visual analogue scale, patient satisfaction, joint-related improvement, and pain comparing technology or alignment groups at three months, six months, one year, and two years. Robotic-assisted surgery had a shorter mean operating time by 11.5 minutes (95% CI 7.3 to 15.9; p < 0.001) and better mean posterior cruciate ligament macroscopic soft-tissue injury score (mean difference 0.7 (95% CI 0.3 to 1.1); p = 0.001) compared with computer-assisted surgery. Mechanical alignment had a higher soft-tissue release rate compared with functional alignment (44.8% vs 8.1%; OR 9.2 (95% CI 4.6 to 18.3); p < 0.001). In most cases, surgeons preferred the use of robotics and functional alignment.
CONCLUSION
Robotic-assisted surgery and functional alignment were not superior to computer-assisted surgery and mechanical alignment, respectively, in improving clinical and functional outcomes up to two years post-TKA.