Description
Effect of anterior-posterior position in extension on kinematics and patient satisfaction after knee arthroplasty.
Objectives: Although the anteroposterior position of the femur after total knee arthroplasty is considered to be more posterior than in the normal knee, we investigated how the anteroposterior position affects total Knee Arthroplasty kinematics and patient satisfaction. Methods: 100 knees of 95 patients who underwent in vivo kinematic analysis of squatting movements after total knee arthroplasty at our institution were included in the study. The mean age was 73.4 years, 18 men and 77 women, and the mean postoperative follow-up was 29.1 months. In vivo kinematic analysis of squatting motion was performed using a 2D/3D registration technique originally developed at our institution, and the internal and external anteroposterior positions during extension between the implants were divided into an anterior and posterior group, and the flexion angle, rotation angle, internal and external rollback, and 2011 Knee Society Scores were examined in relationship to each of these factors. The significance level was set at 0.05 or less. Results: The mean internal/external anteroposterior position in extension was -6.4 ± 5.4 mm. The anterior group (mean -2.1 ± 2.9 mm) had a smaller angle of extension, external rotation angle and in extension and expectation during squatting motion, and a greater amount of medial and lateral rollback compared to the posterior group (mean -10.6 ± 3.8 mm). No differences were found between the anterior and posterior groups in maximum flexion angle, symptoms, satisfaction and functional activities. Conclusions: Anterior-posterior position in extension had an effect on extension angle and rollback, but not on maximum flexion angle or patient satisfaction.
