Patients with Robotic Arm-Assisted Medial Unicompartmental Knee Arthroplasty (mUKA) Regain Their Preoperative Activity Level Two Weeks Earlier Compared to Robotic Arm-Assisted Kinematically Aligned Total Knee Arthroplasty (rKA-TKA)

Abstract

Background: This study compared the early rehabilitation progress of patients undergoing robotic-assisted medial unicompartmental knee arthroplasty (mUKA) and robotic-assisted kinematically aligned total knee arthroplasty (rKA-TKA), focusing on daily activity by step-count measurements. Methods: A retrospective analysis of prospectively collected data from 88 patients (53 rKA-TKA and 35 mUKA) was conducted. Patients wore Garmin Vivofit® 4 activity trackers pre and postoperatively. Daily step counts were analyzed, and clinical outcomes were assessed using various scores, including the Knee Society Score (KSS) and Forgotten Joint Score (FJS). Results: Preoperative median daily step counts were comparable between groups (rKA-TKA: 3988 and mUKA: 4315; p = 0.128). At 6 and 7 weeks post-surgery, the mUKA group showed significantly higher median step counts (3741 and 4730) compared to the rKA-TKA group (2370 and 2910), with p-values of 0.015 and 0.048, respectively. The mUKA group reached 86.7% of their preoperative step count at week 6 and 100% at week 7, while the rKA-TKA group achieved 59.4% and 73%, respectively. Both groups surpassed their preoperative activity levels by week 9. Clinical outcomes at 2 months and 1 year post-surgery showed no significant differences between groups. Conclusions: While both the mUKA and rKA-TKA patients achieved their preoperative daily activity levels within nine weeks post-surgery, the mUKA patients reached this milestone approximately two weeks earlier. This study demonstrates a clinical benefit of mUKA in terms of faster postoperative remobilization, even when compared to kinematically aligned robotic-assisted TKA.