Abstract
Introduction: Currently, minimal attention has been paid to thorough preoperative planning in primary total knee arthroplasty. The aim of this study was to evaluate the results and the effectiveness of a previously reported x-ray view as a simple way of preoperative planning in total knee arthroplasty.
Materials & Methods: The rotational alignment of the distal end of the femur is usually evaluated by measuring the angle (posterior condylar angle, PCA) between the surgical transepicondylar axis (TEA) and the posterior condylar line (PC line), which connects the posterior aspects of the femoral condyles. A simple and convenient technique for assessing the TEA and PC line using plain radiography is the kneeling view. The kneeling view has been described as a posteroanterior projection at right angles to the tibial shaft with the knee in approximately 80° of flexion and with the hip joint in neutral rotation. Preoperative planning is possible using the kneeling view in measuring the rotational alignment of the distal femur using the posterior condylar angle. Additionally, information about the varus inclination of the upper part of the tibia may be obtained using the same x-ray view. Kneeling views were obtained in fifty patients with advanced osteoarthritis (classified as 4 on the Kellgren–Lawrence scale) that were admitted in our department for primary TKA. The varus inclination of the upper part of the tibia and condylar twist angle were measured using digital protractors.
Results: There was no statistically significant correlation between the posterior condylar angle and the varus inclination of the upper part of the tibia. Bivariate linear regression analysis did not reveal any prediction equation or relation between the two computed variables in advanced osteoarthritic knees.
Conclusions: Using this method of preoperative planning, the current practice of cutting the tibia perpendicular to its mechanical axis and applying a predefined external rotation of the femoral component is strongly disputed, especially in advanced osteoarthritic knees. The results of this study show that preoperative planning may be very helpful in assessing the rotational deformity of the distal femur. The final amount of external rotation of the femoral component must be approached on an individual basis based on a thorough preoperative planning.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
