Prospective, randomised controlled trial comparing robotic arm-assisted bi-unicompartmental knee arthroplasty to total knee arthroplasty.

Purpose: The objective of this study was to compare the clinical outcomes 2 years following surgery between robotic-arm assisted bi-unicompartmental knee arthroplasty (bi-UKA) compared with conventional mechanically aligned total knee arthroplasty (TKA).
Methods: This is a single-centre, double-blinded, randomised controlled trial comparing bi-UKA and TKA. Patient-reported outcome measures (PROMs) were collected from 60 patients (27 bi-UKA and 33 TKA patients) 2 years following surgery, including Oxford Knee Score (OKS), New Knee Society Score (NKSS), Forgotten Joint Score, EQ-5D-3L, UCLA activity scale, Hospital Anxiety and Depression Scale, Pain and Stiffness Visual Analogue Scales, Satisfaction and Range of Motion. Complications were also recorded at each visit.
Results: TKA and bi-UKA continue to offer comparable PROMs. The clinical NKSS demonstrated a significant difference between the two interventions, TKA 59.5 (37-65) versus bi-UKA 26.0 (22-40) (p < 0.001). There were no significant differences shown between the interventions across all time points and remaining outcome measures (OKS at 2-year follow-up; TKA-42.0 [34.0-45.5] vs. bi-UKA-41.0 [28.0-45.0]) or the proportion of participant achieving bi-phasic gait at 2 years following surgery (p = 0.429). There was no difference in complication rates following surgery at 2 years.
Conclusion: Robotic arm-assisted, cruciate-sparing bi-UKA and mechanically aligned TKA offer similar clinical outcomes 2 years following surgery with no difference in complication rates. Further, follow-up is required to monitor patients as they enter mid/long-term follow-up and determine whether patients will gain long-term benefits from the cruciate-sparing bi-UKA approach.
Level of Evidence: Level I.
(© 2025 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)