Comparison of intraoperative kinematics between cruciate-retaining and medial-stabilized inserts in total knee...

The kinematics of total knee arthroplasty (TKA) have been shown to affect postoperative function and patient satisfaction. A medial stabilized (MS) insert was designed to improve kinematics by enhancing medial stability and inducing lateral rollback in comparison to cruciate-retaining (CR) inserts. This study aimed to compare the intraoperative kinematic patterns between CR and MS inserts in TKA using a CT-free navigation system.

A total of 23 knees from 21 patients who underwent primary TKA for osteoarthritis were included. A CT-free navigation system (BrainLab KNEE3) was used to record intraoperative kinematics during the CR and MS insert trials. Kinematic parameters, including kinematic patterns, such as anteroposterior (AP) translation of the medial and lateral condyles and rotational angles, were analyzed based on range of motion.

The MS insert exhibited significantly less medial AP translation compared to the CR insert (7.0 ± 5.0 vs. 10.3 ± 5.1 mm, p = 0.04). No significant differences were observed in the lateral AP translation (11.5 ± 6.2 vs. 12.8 ± 5.2 mm, p = 0.41), rotational angle (6.3 ± 4.5 vs. 4.7 ± 4.4, p = 0.20), or kinematic patterns.

MS inserts may enhance stability by reducing medial translation. Their effect on reproducing medial pivot kinematics is comparable to that of the CR inserts.