The purpose of this study is to investigate the three-dimensional (3D) kinematics of preoperative osteoarthritic (OA) knees, and to clarify the validity of the findings in comparison with previous studies of kinematics in normal and OA knees.
Fifteen preoperative OA knees were scanned by 3D computed tomography (CT) at three positions. We created 3D bone models and quantitatively evaluated motion of the knee joint using a markerless volume-based registration technique. Assessment categories comprised rotation angles and anterior-posterior (AP) translation. The Pearson correlation test was used to analyze correlations between rotational angle and femorotibial angle.
From maximum extension to 90° flexion, 11 femurs displayed internal rotation relative to the tibia. In 10 knees, the sulcus moved >1 mm more backward than the lateral epicondyle. Significant differences were apparent between movement of the sulcus and lateral epicondyle. A correlation of -0.42 was found between the rotational angle and femorotibial angle.
The kinematics of OA knees differed from that of normal knees in that femurs did not present external rotation with flexion. One reason for this movement is that the medial condyle of the femur tended to move backward in knee flexion due to disruption of the tibial joint surface.