Clinical and radiographic outcomes of ROSA robotic-assisted total knee arthroplasty: a retrospective comparison of anatomic (persona) versus symmetric (vanguard) implant designs.

Whether an anatomic or a symmetric implant performs better when both are implanted on the same robotic platform remains unclear. We therefore compared short-term clinical and radiographic outcomes of the anatomic Persona and the symmetric Vanguard designs in ROSA robotic-assisted total knee arthroplasty (TKA). Sixty-four consecutive patients (33 Vanguard, 31 Persona), all receiving a posterior-stabilized bearing, were reviewed retrospectively at a single center with a minimum follow-up of 12 months. Outcome measures were the Oxford Knee Score (OKS), Knee Society Score (KSS), range of motion (ROM) assessed preoperatively and postoperatively, planned and achieved femoral (FC) and tibial (TC) component angles measured by ROSA before resection and at cut validation, hip-knee-ankle (HKA) alignment with a >3° outlier threshold, and operative time. OKS and KSS improved significantly from baseline in both groups (all p < 0.001), and the groups did not differ at 12 months (OKS p = 0.080; KSS p = 0.100). Preoperative ROM was comparable (flexion p = 0.81; extension deficit p = 0.73). Flexion was greater in the Persona group (122.2 ± 9.1° vs. 115.2 ± 7.7°; p < 0.001; d = 0.83) and the extension deficit smaller (6.2 ± 3.1° vs. 8.7 ± 2.6°; p = 0.001; d = 0.90). Postoperative HKA was similar (2.80 ± 0.59° vs. 2.65 ± 0.64°; p = 0.245); one Vanguard patient exceeded the 3° threshold, and no Persona patient did. Of the achieved component angles, FC coronal flexion (p = 0.028) and TC coronal varus (p = 0.018) differed between groups. With both implants, ROSA-assisted TKA achieved equivalent HKA alignment within the range reported for the platform and excellent, comparable patient-reported outcomes. Small implant-specific differences remained in the achieved component angles. The Persona design was also associated with a range-of-motion advantage with large effect sizes, a finding specific to this retrospective cohort. These early findings should be tested in larger randomized trials with longer follow-up. Level of Evidence. III (retrospective cohort study).