To investigate the effects of suture (soft tissue closure) and air tourniquet use on intraoperative kinematics in navigated total knee arthroplasty.
The study included 20 patients with varus-type knee osteoarthritis who underwent primary posterior-stabilized total knee arthroplasty using computed tomography (CT)-based navigation. Intraoperative tibiofemoral kinematics from maximum extension to maximum flexion were measured using the computed tomography-based navigation. The measurements were performed 3 times as follows: measurement 1: before suture (tourniquet on), measurement 2: after suture (tourniquet on), and measurement 3: after tourniquet removal. Details of kinematics including knee joint gap, tibiofemoral rotational angles, and anteroposterior (AP) distance between the femur and tibia were compared among the 3 measurements and statistically evaluated.
On the medial side, there was no significant difference among the 3 measurements in the extension gap, but measurement 1 showed a significantly larger flexion gap compared with the other 2 measurements. On the lateral side, there was no significant difference between the extension and flexion gaps in all measurements. The anteroposterior distance in measurement 1 showed that the femur was positioned significantly more anterior to the tibia at 10° and 20° of flexion compared with the other 2 measurements after suture. There was no significant difference among the 3 measurements in the tibiofemoral rotation angles.
These results found that the effect of suture and tourniquet was minimal, and that intraoperative kinematics can effectively evaluate postoperative passive kinematic conditions.