Improved Accuracy With a Novel Imageless Robotic-Assisted System Versus Manual Instrumentation in Unicondylar Knee Arthroplasty: A Cadaveric Study

Background Unicondylar knee arthroplasty (UKA) is a highly effective procedure for patients with end-stage single compartment osteoarthritis resulting in faster recovery and improved patient outcomes than total knee arthroplasty. However, higher revision rates remain a concern, contributing to increased utilization of robotic-assisted systems to support more accurate implant placement with the goal of reducing the most common reasons for revision. Methods This study aimed to compare the resection accuracy of a robotic-assisted unicondylar knee arthroplasty (rUKA) compared to manual instrumentation (mUKA) in a controlled cadaveric study. Six surgeons performed bilateral UKA on 40 cadaveric specimens; rUKA on 1 leg and mUKA on the other. The specimens were computed tomography scanned preprocedure and postprocedure with the achieved resection angles compared to the planned. Resection depth accuracy was assessed by measuring the resected bone (with a caliper) accounting for the saw blade thickness. Results The robotic-assisted UKA was found to have significantly greater accuracy for the angle of the resections than mUKA including tibial varus/valgus, tibial posterior slope, femoral varus/valgus, flexion/extension, and internal/external rotation. Both mUKA and rUKA procedures were found to have a high level of accuracy for the hip-knee-ankle angle and bone resection depths. rUKA had significantly fewer outliers than mUKA for the femur flexion/extension, internal/external rotation, tibial varus/valgus, and tibial flexion/extension. Conclusions The rUKA demonstrated increased accuracy of the angle of resections compared to mUKA which may support increased consistency and reproducibility of the UKA procedure.