Zhao R, et al. - In this study, the accuracy of soft tissue balancing using surgeon-defined assessment (SDA) and gap-balancer (GB) compared with a sensor was explored. Researchers prospectively included a total of 48 patients undergoing total knee arthroplasty (60 knees). The SDA, GB, and sensor data were compared to estimate the sensitivity, specificity, and accuracy at 0°, 45°, 90°, and 120° flexion. They conducted cumulative summation analysis to evaluate the surgeon’s performance during the sensor introductory phase. SDA was found to be a poor predictor of knee balance. The accuracy of soft tissue balancing was improved by GB, but was still less accurate than the sensor, particularly for unbalanced knees. Except at 45° flexion, SDA improved with the ongoing use of the sensor.