Determination of Knee Joint Line Positioning by Femoral Bicondylar and Epicondylar Distances in the Brazilian Population.

Objective: To determine the positioning of the knee joint line height based on anatomical references, that is, the distance of the femoral condylar bicortical axis and the medial and lateral epicondylar distances in the Brazilian population. Methods: We analyzed 500 magnetic resonance imaging tests of the knees of 250 women and 250 men to measure the condylar bicortical axis (CBA) and the distance of the joint height to the medial epicondyle (MED) and to the lateral epicondyle (LED). Results: The mean age of the patients was 50.91 years old, with a standard deviation (SD) of ± 14.76. The mean CBA distance was 72.11 ± 5.93 mm. The mean MED and LED values were 33.39 ± 3.50 mm and 26.32 ± 4.08 mm, respectively. The formulas to estimate the distance of the joint line from the medial and lateral epicondyles were MED = 0.4618 x CBA and LED = 0.3615 x CBA for male subjects and MED = 0.4653 x CBA and LED = 0.3767 x CBA for female subjects using a 95% confidence interval. Conclusion: The distance to the femoral CBA can be a reference for determining the joint line positioning from the distances of the medial and lateral femoral epicondyles.