Relationship between intra-operative rotational knee kinematics and clinical outcomes in mechanically aligned bicruciate stabilized total knee arthroplasty

The aim of this study was to investigate the relationship between intra-operative rotational knee kinematics and clinical outcomes in mechanically aligned bicruciate stabilized (BCS) total knee arthroplasty (TKA). The impact of pre-to post-operative changes in tibial rotation on intra-operative rotational kinematics was also examined. A total of 117 primary cemented mechanically aligned BCS TKAs were performed using the CORI robotic system for patients with varus osteoarthritis. Tibial internal rotation was measured intra-operatively after implantation from 0° extension to 30°, 60°, 90°, and 120° flexion. The difference in tibial rotation between the pre-operative maximal extension and post-operative 0° extension was also recorded. Correlations between tibial rotation during knee flexion and clinical outcomes, including range of motion (ROM), 2011 Knee Society Score (2011 KSS), and Forgotten Joint Score-12 (FJS-12), at 6 weeks, 3 months, and 6 months were analyzed. Correlations between pre-to post-operative tibial rotational changes and tibial rotation during flexion were also assessed. Significant tibial internal rotation was observed throughout flexion. Tibial internal rotation correlated positively with ROM, 2011 KSS, and FJS-12 at 6 weeks and 3 months, but not at 6 months. A significant negative correlation was found between the increase in tibial internal rotation at post-operative 0° extension relative to the pre-operative maximal extension and the amount of tibial internal rotation during flexion. Tibial internal rotation during flexion correlated positively with early outcomes, but this was not sustained at 6 months. An increase in tibial internal rotation at 0° extension compared with the pre-operative maximal extension negatively affected rotational kinematics. • Rotational knee kinematics were evaluated in bicruciate stabilized total knee arthroplasty using CORI. • Tibial internal rotation during flexion correlated with early clinical outcomes. • Positive correlations were found at 6 weeks and 3 months, which were not sustained at 6 months. • Increase in tibial rotation at extension versus pre-operative negatively affected kinematics.