Abstract
Background
Manually instrumented knee arthroplasty is associated with variability in implant and limb alignment and ligament balance. When malalignment, patellar maltracking, soft tissue impingement or ligament instability result, this can lead to decreased patient satisfaction and early failure. Robotic technology was introduced to improve surgical planning and execution. Haptic robotic-arm assisted total knee arthroplasty (TKA) leverages three-dimensional planning, optical navigation, dynamic intraoperative assessment of soft tissue laxity, and guided bone preparation utilizing a power saw constrained within haptic boundaries by the robotic arm. This technology became clinically available for TKA in 2016. We report our early experience with adoption of this technique.
Methods
A retrospective chart review compared data from the first 120 robotic-arm assisted TKAs performed December 2016 through July 2018 to the last 120 manually instrumented TKAs performed May 2015 to January 2017, prior to introduction of the robotic technique. Level of articular constraint selected, surgical time, complications, hemoglobin drop, length of stay and discharge disposition were collected from the hospital record. Knee Society Scores (KSS) and range of motion (were derived from office records of visits preoperatively and at 2-weeks, 7-weeks and 3-month post-op. Manipulations under anesthesia and any reoperations were recorded.
Results
Less articular constraint was used to achieve balance in the robotic group, with a higher incidence of cruciate retaining retention (92% vs. 55%, p < 0.01) and a trend towards lower use of varus-valgus constrained articulations (5% vs. 11%, p = 0.068). Robotic surgery increased mean operative time by 22 minutes (p < 0.001). Operative time improved by 26 minutes from the first 10 robotic cases to the last 10 robotic cases. The robotic group had a lower hospital length of stay (2.7 vs. 3.4 days, p < 0.001). Discharge home was not significantly different between robotic and manual groups (89% vs. 83%, p = 0.2). Postoperative Knee Society scores were similar between groups at each postoperative time interval. Robotic-arm assisted TKA patients demonstrated lower mean flexion contracture at 2-weeks (1.8 vs. 3.3 degrees, p < 0.01), 7-weeks (1.0 vs. 1.8 degrees, p <0.01), and 3-months (0.6 vs 2.1 degrees, p = 0.02) post-surgery, but these differences were small. Mean flexion did not differ between groups at 3-month follow-up, but motion was achieved with a significantly lower rate of manipulation under anesthesia in the robotic group (4% vs 17%, p = 0.013).
Conclusion
Preliminary findings demonstrate robotic-arm assisted TKA is safe and efficacious with outcomes comparable, if not superior, to that of manually instrumented TKA.
Keywords
total knee arthroplasty, robotic arm-assisted total knee arthroplasty
For any figures or tables, please contact authors directly.
