Improved implant position and lower revision rate with robotic-assisted unicompartmental knee arthroplasty

PurposeThe aim of this case-control study was to compare implant position and revision rate for UKA, performed with either a robotic-assisted system or with conventional technique.MethodsEighty UKA (57 medial, 23 lateral) were performed with robotic assistance (BlueBelt Navio system) between 2013 and 2017. These patients were matched with 80 patients undergoing UKA using the same prosthesis, implanted using conventional technique. The sagittal and coronal component position was assessed on postoperative radiographs. The revision rate was reported at last follow-up.ResultsThe mean follow-up was 19.7 months 9 for the robotic-assisted group, and 24.2 months 16 for the control group. The rate of postoperative limb alignment outliers (2 degrees) was significantly higher in the control group than in the robotic-assisted group for both lateral UKA (26% in robotic group versus 61% in control group; p=0.018) and medial UKA (16% versus 32%, resp.; p=0.038). The coronal and sagittal tibial baseplate position had significantly less outliers (+/- 3 degrees) in the robotic-assisted group, than in the control group. Revision rates were: 5% (n=4/80) for robotic assisted UKA and 9% (n=7/80) for conventional UKA (n.s.). The reasons for revision were different between groups, with 86% of revisions in the control group occurring in association with component malposition or limb malalignment, compared with none in the robotic-assisted group.Conclusion Robotic-assisted UKA has a lower rate of postoperative limb alignment outliers, as well as a lower revision rate, compared to conventional technique. The accuracy of implant positioning is improved by this robotic-assisted system.Level of evidence Level of evidence III. Retrospective case-control studyClinical relevance This is the first paper comparing implant position, clinical outcome, and revision rate for UKA performed using the Navio robotic system with a control group.