Does the Use of a Robotic Gap-tensioning System Improve Functional Outcomes After TKA? A Randomized Clinical Trial

Robotic-assisted TKA may allow for more reproducible balancing and implant positioning. However, few RCTs have directly compared modern robotic-assisted TKA to conventional TKA.

(1) Do patients undergoing robotic-assisted TKA perform better on the Timed Up and Go (TUG) test and Stair Climb test (SCT) than patients undergoing conventional TKA at 1 and 6 months after surgery? (2) Do patients undergoing robotic-assisted TKA demonstrate better patient-reported outcomes, including Knee Injury and Osteoarthritis Outcome Score (KOOS), EQ-5D, and VAS scores, than patients undergoing conventional TKA at 1 and 6 months after surgery? (3) Do patients undergoing robotic-assisted TKA demonstrate better radiographic alignment and position than patients undergoing conventional TKA?

In this double-blind RCT, 60 patients were randomized to robotic-assisted TKA (n = 30) or conventional TKA (n = 30) without the use of a tensioning device. All care was otherwise standardized, using mechanical alignment guides. The primary outcome measures were the TUG and SCT tests; results were collected by a blinded observer at 6 months postoperatively. These time points were chosen based on the maximal early improvement in patient-reported outcomes and bimodal distribution of the TUG and SCT tests, worsening in the immediate postoperative period, and improving within the first 6 months. Secondary outcome measures were KOOS, EQ-5D, and VAS scores; radiographic measurements; and operative time. Standard bivariate statistical analysis was conducted. The mean ± SD age of the cohort was 66 ± 7 years, with no differences between groups (p = 0.21). Ninety-three percent (28 of 30) of patients in the robotic-assisted group were White versus 97% (29 of 30) in the conventional TKA group (p > 0.99). Women made up 57% (17) of the robotic-assisted cohort and 60% (18) of the conventional TKA cohort. No differences were noted between the robotic-assisted and conventional TKA groups in BMI, Charlson comorbidity index, or American Society of Anesthesiologists (ASA) classification.

Patients undergoing robotic-assisted TKA did not perform better than those who underwent conventional TKA on the TUG (11 versus 11 seconds; p = 0.88) or SCT (15 versus 15 seconds; p = 0.93) tests. Patients undergoing robotic-assisted TKA did not demonstrate better mean ± SD scores on the KOOS pain subscale than patients undergoing conventional TKA (86 ± 14 versus 80 ± 17; p = 0.15). Patients undergoing robotic-assisted TKA did not demonstrate better radiographic alignment and position than patients undergoing conventional TKA based on hip-knee-ankle angle (178° versus 178°; p = 0.89). No differences between the two groups were noted at the 1-month follow-up in TUG and SCT test results.

In this study, patients who underwent robotically assisted TKA did no better in terms of function, patient-reported outcomes, or radiographic measures than did patients who underwent conventional TKA. Until or unless future studies demonstrate benefits of robotically assisted TKA that are large enough for patients to perceive, we recommend against its use.

Level I, therapeutic study.