Sensor-guided Knee Balancing in Posterior-stabilized Total Knee Arthroplasty: A Surgical Description and Report of Medium-term Patient Outcomes

Background: Intraoperative pressure sensors provide the ability to quantify soft tissue balance (STB) and guide balancing interventions in total knee arthroplasty (TKA). The purpose of this study was to validate a sensor-guided knee balancing algorithm for posterior-stabilized TKA and then report medium-term patient-reported outcome measures from a consecutive series of surgeries using this algorithm. Materials and Methods: An algorithm is described for sensor-guided soft tissue releases and bone recuts aiming for quantitative knee balance. The coprimary endpoints were the proportion of TKAs in which quantitative STB was achieved using the sensor-guided balancing algorithm and the number of balancing interventions required. Secondary outcomes included change in Knee injury and Osteoarthritis Outcome Score (KOOS) components, rates of manipulations for stiffness, and revision surgery. Results: In a consecutive series of 210 knees, quantitative STB was achieved in 91.9% of cases. Balancing procedures were required in 57.2% (n=120), with 84.3% (n=177) requiring up to 2 balancing interventions to achieve balance. Angular bone recuts were required in 22.9% (n=48) of TKAs. At a minimum of 2 years, there was a statistically significant, clinically meaningful increase in mean KOOS4 of 40.8 (SD=17.5). All ΔKOOS subscales improved. The incidence of manipulation for stiffness and revision surgery at up to 4 years were 3.3% (7/210) and 1.4% (3/210), respectively. Conclusions: Quantitative sensor-guided assessment allows precise attainment of STB using a balancing algorithm of both bone recuts and soft tissue releases. Excellent medium-term improvement in patient-reported outcome measures was achieved with posterior-stabilized TKA using intraoperative sensor-guided balancing interventions.