Use of robotics may facilitate earlier functional recovery and reduce overcorrection compared to conventional implantation techniques in total knee arthroplasty: a single-surgeon cohort study.

backgroundTotal Knee Arthroplasty (TKA) is a highly successful procedure to treat osteoarthritis. Yet a relevant number of patients complain about persisting pain. In the present study, patient satisfaction, functional outcomes, and radiological parameters were evaluated in a retrospective single-surgeon analysis. Conventional implantation was compared with a robotic system that uses computed tomography (CT)-based planning for haptically guided bone preparation (MAKO/Stryker), hypothesizing that the use of robotics would lead to improved early function and potentially different radiological alignment.

methodsThe first 150 consecutive robotic-TKAs of one surgeon were compared with the manually operated TKAs number 8000-8150 in a retrospective cohort study using the same implanting philosophy and pre-, intra-, and postoperative conditions and workflows with exception of the robotic-assisted component. Patients undergoing primary TKA for osteoarthritis resistant to conservative treatment were included; exclusion criteria were age < 18 years, rheumatic disease, or complex preoperative traumatic injury. Both groups shared the same implanting philosophy and perioperative workflows, with exception of the robotic assistance. Key outcomes included the Hospital for Special Surgery (HSS) score, functional recovery milestones, and radiological parameters.

resultsFunctionally, patients in the robotic TKA groups reached 90° of knee flexion much earlier with a medium of 5 (2-10) days postoperatively when compared to the manually operated group (8 [5-12] days (p < 0.001). Pain at discharge was slightly higher in this group with median NRS values of 2 (1-7) versus 1 (1-4) in the manually operated group (p < 0.001) with patients being discharged, however, three days earlier in the robotic group. Interestingly, mechanical axis deviation showed a greater variation in the robotic TKA group than in the manual TKA group with the median being more in varus (-6 [-20-30] mm vs. -1 [-19-17] mm, p < 0.001). One year postoperatively, the HSS Score was marginally higher in the robotic group with (73 (45-83) vs. 70 (58-70), p < 0.001), however, still below the minimal clinically important difference.

conclusionThe data from this study suggest that patients operated with such a robotic system may be mobilized earlier and also show less overcorrection compared to those operated by a conventional technique. The long-term benefit remains, however, still unclear.