Abstract
An Image-Free Knee Navigation System (Stryker), able to analyze kinematics curves and the kinematics values, was evaluated. Forty-five TKA (26 CR and 19 PS types) were performed using this navigation system. Kinematics curves were categorized into the following groups: a reversed patella group, a reduced patella group and a cramped patella group. This navigation system has a function to predict the post-operative balance of the knee intraoperatively; this was very practical for our evaluation, and unique. Differences between CR and PS knees were evaluated in the cramped patella group. Kinematics values could be recorded only once, so the differences between CR and PS knees were evaluated only in the reduced patella group.
The results show that the medial collateral ligaments of the reversed patella group were more lax than those in the reduced patella group (P<001) and the laxity of the medial collateral ligament in the cramped patella group was less at all angles of the kinematics curves (P<0.01) . Differences between CR and PS knees were not significant. Regarding the kinematics values, PS knees showed more internal rotation than CR knees (P<0.05) .
This study indicates that this Navigation System offers a possibility of evaluating knee kinematics during surgery, and further improvement of the system is required for a better analysis.
