ABSTRACT
This study investigated the six degrees of freedom (DOF) kinematics and three-dimensional (3D) contact during kneeling after total knee replacement arthroplasty. A total of 16 South Korean female patients (22 knees) after posteriorly stabilized (PS) TKA (LPS-Flex) performed by a single surgeon were randomly recruited. The patients were imaged using a dual fluoroscopic technique while they were kneeling from initial to maximum flexion. The acquired images and 3D models were then used to recreate the in vivo pose of the components Patients flexed their knee, on average, from 107.3degrees to 128.0degrees during the kneeling activity. Changes in kinematics included proximal, medial, posterior translation and varus rotation. Articular contact moved posteriorly by 5.9 mm and 6.4 mm in the medial and lateral compartments, respectively. Contact also moved medially by 3.2 mm and 5.8 mm in the medial and lateral compartments. A decrease in articular contact was observed in both condyles, and lateral condylar lift-off increased with flexion (P=0.0001). The tibiofemoral and cam/post articular contact data acquired in this study further suggest that kneeling may be performed by patients after clinically successful PS TKA who feel comfortable with activity and are free of