The Learning Curve of Reaching the Planned Limb Alignment in Robotic-Arm-Assisted Total Knee Arthroplasty

Abstract

Evidence on the learning curve associated with robotic-arm-assisted total knee arthroplasty (ra-TKA) is scarce and mostly based on operative time. Thus, the objective of this study was to assess a surgeon's learning experience based on accuracy to reach planned limb alignment and its impact on surgical-characteristics, limb-alignment, and perioperative-outcomes. A retrospective chart review was conducted on a consecutive series of 204 primary ra-TKAs (patients), performed by a single surgeon in a single institution (3/7/2018-to-6/18/2019). Cumulative summation control sequential analysis was used for the assessment of the learning curve using accuracy of reaching the planned limb alignment establishing that surgeries had an initial-learning-phase, followed by a second-consolidation-phase. Baseline demographics, operative/tourniquet times, prosthesis type, and limb alignment were compared between these two phases. Length of stay, discharge disposition, complications, reoperation/readmission (90 days), and total morphine equivalents (TMEs) prescribed were compared between phases. Independent sample t-tests, and chi-squared analyses were performed. ra-TKA demonstrated a learning curve of 110 cases for reaching planned limb alignment (p = 0.012). Robotic experience resulted in significantly more proportion of knees in neutral-axis postoperatively (p = 0.035) and significant reduction in TMEs prescribed (p = 0.04). The mean operative and tourniquet time were found to be significantly lower in second-phase versus the first-phase (p for both < 0.0001). ra-TKA has a significant learning curve in clinical practice. A surgeon can reach the planned limb alignment with increased accuracy over time (110-cases). Progressive robotic learning and associated operative time efficiency can lead to significantly lower opioid consumption in patients undergoing TKA.

No Benefit of Robotic-Assisted over Computer-Assisted Surgery for Achieving Neutral Coronal Alignment in Total Knee Arthroplasty

“…21 Pannu et al demonstrated 110 cases are needed to finally achieve the planned limb alignment when MAKO RAS system is utilized, seemingly aMA, although not explicitly described in the study. 22 In the present study, 20 initial cases were excluded due to the initial learning curve, but the results observed match previous learning curve studies demonstrating little to no learning curve in terms of implant position. 13,23,24 Winnock de Grave et al demonstrated superior outcomes of inverse kinematic when compared with aMA.…”

“…A recent meta-analysis demonstrated better accuracy and better patient-reported outcomes with the use of RAS, not controlling for alignment, rather the planned and achieved alignment 21 . Pannu et al demonstrated 110 cases are needed to finally achieve the planned limb alignment when MAKO RAS system is utilized, seemingly aMA, although not explicitly described in the study 22 . In the present study, 20 initial cases were excluded due to the initial learning curve, but the results observed match previous learning curve studies demonstrating little to no learning curve in terms of implant position 13,23,24 .…”