A new robotically assisted technique can improve outcomes of total knee arthroplasty comparing to an imageless navigation system

Arch Orthop Trauma Surg. 2023 May;143(5):2701-2711. doi: 10.1007/s00402-022-04560-9. Epub 2022 Aug 1.


Background: Robotic assisted total knee arthroplasty (RTKA) has shown improved knee alignment and reduced radiographic outliers. However, there remains debate on functional outcomes and patient-reported outcomes (PROMs). This study compares the 1-year clinical outcomes of a new imageless robotically assisted technique (ROSA Knee System, Zimmer Biomet, Warsaw, IN) with an imageless navigated procedure (NTKA, iAssist Knee, Zimmer, Warsaw, IN).

Methods: The study is a retrospective analysis of prospectively collected data that compared the functional outcomes and PROMs of 50 imageless RTKA with 47 imageless NTKA at 1-year follow-up. Baseline characteristics, intraoperative and postoperative information were collected including complications, revisions, Knee Society Score (KSS), Knee injury and Osteoarthritis Outcome Score (KOOS) score, and Forgotten Joint Score (FJS-12). Radiographic analysis of preoperative and postoperative images evaluating hip-knee-ankle (HKA) angle was performed.

Results: There was no difference regarding baseline characteristics between the groups. Mean operative time was significantly longer in the RTKA group (122 min vs. 97 min; p < 0.0001). Significant differences were reported for the "Pain" (85 [RTKA] vs 79.1 [NTKA]; p = 0.0283) subsection of the KOOS score. In addition, RTKA was associated with higher maximum range of motion (119.4° vs. 107.1°; p < 0.0001) and better mean improvement of the arc of motion by 11.67° (23.02° vs. 11.36°; p < 0.0001). No significant differences were noted for other subsections of KOOS, KSS, FJS-12, complications, or limb alignment at 1-year follow-up.

Conclusions: Imageless RTKA was associated with longer surgical time, better pain perception and improved ROM at 12-month follow-up compared with NTKA. No significant differences were reported on other PROMs, complication rates and radiographic outcomes.

Level of evidence: III.

Keywords: Complications; Imageless navigation; Imageless robotic TKA; Patient-reported outcomes; Robotic-assisted total knee arthroplasty; Total knee arthroplasty.

MeSH terms

  • Arthroplasty, Replacement, Knee* / methods
  • Humans
  • Knee / surgery
  • Knee Joint / surgery
  • Knee Prosthesis*
  • Osteoarthritis, Knee* / surgery
  • Retrospective Studies
  • Robotic Surgical Procedures*