Manually instrumented total knee arthroplasty (TKA) is associated with variable implant and limb alignment and ligament balance. These inconsistencies may contribute to knee instability, decreased patient satisfaction, and early implant failure. Robot-assisted technology was introduced to improve surgical planning and execution. Robot-assisted TKA involves the use of optical navigation and three-dimensional planning software preoperatively and intraoperatively to accurately assess soft-tissue balancing. Bone preparation is performed with a power saw that is kept within haptic boundaries by the robotic arm, allowing for more precise cuts. Limited early reports of robot-assisted TKA describe improved alignment, less soft-tissue damage, and enhanced patient outcomes. Robotic soft-tissue balancing allows for intraoperative adjustments to planned limb and component alignment based on navigated assessment of soft-tissue laxity.

This video describes our technique for robot-assisted soft-tissue balancing and presents the early outcomes of patients who underwent robot-assisted TKA compared with the outcomes of patients who underwent manual TKA. The study included the first 66 consecutive robot-assisted TKA procedures performed by a single surgeon at a university-affiliated teaching hospital between December 2016 and December 2017 and the last 66 consecutive manually-instrumented TKA procedures performed between May 2016 and December 2016. Surgical time, blood loss as measured by hemoglobin level, length of stay, and discharge disposition were collected from electronic hospital records. Knee Society Scores and range of motion were evaluated at 3 weeks, 7 weeks, and 3 months postoperatively. The mean surgical time for the robotic cohort was longer than that for the manual cohort (136 minutes versus 112 minutes; P < 0.001). Mean blood loss between the cohorts was comparable (1.7 g/dL versus 1.8 g/dL; P = 0.97). The robotic cohort had a significantly shorter mean hospital length of stay than the manual cohort (2.8 days versus 3.5 days; P < 0.001). A higher rate of discharge to home was reported in in the robotic cohort compared with the manual cohort (91% versus 80%; P = 0.14). The mean postoperative Knee Society Score was higher in the robotic cohort than the manual cohort at 3 weeks postoperatively (116.6 versus 104.1; P = 0.26), 7 weeks postoperatively (141.8 versus 134.5; P = 0.25), and 3 months postoperatively (152.2 versus 146.3; P = 0.75). Mean flexion was better in the robotic cohort than the manual cohort at 3 weeks postoperatively (93.6° versus 92.4°; P = 0.79), 7 weeks postoperatively (109.9° versus 104.8°; P = 0.15), and 3 months postoperatively (111.3° versus 106.2°; P = 0.21). In addition, mean flexion contracture was lower in the robotic cohort than the manual cohort at 3 weeks postoperatively (1.8° versus 3.4°; P = 0.12), 7 weeks postoperatively (0.5° versus 1.5°; P < 0.01), and 3 months postoperatively (0.3° versus 1.7°; P < 0.01). Robot-assisted TKA is advantageous for preoperative planning, soft-tissue balancing, soft-tissue protection, and bone preparation. Robot-assisted TKA was associated with a decreased hospital length of stay and an increased rate of discharge to home. Although robot-assisted TKA was associated with longer surgical times, no increase in blood loss was reported. Patients who underwent robot-assisted TKA had improved Knee Society Scores and range of motion during the early postoperative period. Similar to early studies on robot-assisted TKA, we found that robot-assisted TKA is safe and effective, with outcomes comparable to, if not superior than, those of manually-instrumented TKA.