Abstract
Recently, kinematically aligned total knee arthroplasty has been found to achieve
better clinical outcomes than mechanically aligned TKA. Despite the good clinical
outcomes that are reported at short- to mid-term follow-up, intraoperative variables
that are associated with a better outcome have not been measured. Therefore, this
study was conducted to compare intraoperative kinematics/soft tissue balance and the
clinical outcomes of patients who underwent modified kinematically (restricted tibial
cut) or mechanically aligned total knee arthroplasty. Sixty cruciate-retaining total
knee arthroplasties (30 modified kinematically [3-degree varus and 7-degree posterior
slope in tibial cut] and 30 mechanically aligned) were performed in patients with
varus-type osteoarthritis using a navigation system. Intraoperative kinematics assessed
by the navigation system and soft tissue balance assessed by an offset-type tensor
were compared between the groups. One year postoperatively, the range of motion and
2011 Knee Society scores were compared between the groups. Kinematic assessment exhibited
that tibial internal rotation during flexion was significantly maintained in the kinematic
compared with the mechanical group (p < 0.05). Varus/valgus ligament balance at 90 and 120 degrees of flexion significantly
maintained lateral laxity in the kinematic compared with the mechanical group (p < 0.05). Improvement of flexion angles, functional activity scores, and patient satisfaction
were significantly better in the kinematic than in the mechanical group (p < 0.05). Modified kinematically aligned cruciate-retaining total knee arthroplasty
maintained more tibial internal rotation and lateral laxity during flexion than mechanically
aligned total knee arthroplasty; thus, the former may result in better clinical outcomes.
Keywords
total knee arthroplasty - kinematic alignment - mechanical alignment - soft tissue
balance - kinematics
