Posterior-stabilized total knee arthroplasty using the pre-cut technique achieves mid-flexion stability, but yields only a 50 % medial-pivot pattern.

Abstract

The mid-flexion stability in posterior stabilized (PS)- total knee arthroplasty (TKA) using the pre-cut technique and the relationship between surgical technique and knee kinematics are unclear. This study aimed to evaluate the virtual gap and intraoperative kinematics of PS-TKA using the pre-cut technique. In this retrospective study, 55 patients who underwent PS-TKA for knee osteoarthritis with a navigation system using the pre-cut technique. The mean age at operation was 77.2 years, with 50 female patients. The implant was the Attune PS rotating platform, and a CT-free navigation system was employed. The virtual gap after implantation, as well as the intraoperative knee kinematics before bone cutting and after implantation, were measured using the navigation system. Intraoperative knee kinematics pattern was investigated whether medial pivot (MP) pattern or not. No significant differences were observed in the virtual gap between the medial and lateral sides at any knee flexion angle after implantation. The lateral condyle moved significantly posteriorly during flexion compared to the medial condyle (60°-130°). Regarding knee kinematics after implantation, 50.9 % of patients were classified as having the MP pattern. The knee kinematic pattern after implantation was significantly influenced by the kinematic pattern before bone cutting (p < 0.01). PS-TKA using the pre-cut technique can achieve stability across the entire range of motion, including mid-flexion. However, the proportion of patients exhibiting an MP pattern after implantation was only approximately 50 %.