Variation in the Posterior Condylar Angle

Abstract

Background: Clinical success of TKR depends to a large extent on the correct positioning of the implants. The femur cut is usually made in 3° of external rotation relative to the posterior aspect of the femoral condyles, which is a typical value of the Posterior Condylar Angle (PCA). The aim of this study was to assess variation in the PCA and to identify possible correlations between the value of the PCA and the following parameters: gender, body side, body height and weight (BMI).

Material and methods: The study group comprised 75 patients who underwent an Angio-CT study between 2012 and 2014 due to a suspected vascular disorder. For each knee, we measured the Posterior Condylar Angle and the Posterior Twist Angle.

Results: The mean Posterior Condylar Angle was 2.7±2.1°. The differences between males and females were not statistically significant. The angles showed a high degree of symmetry between the contralateral knees.

Conclusions: 1. Positioning of the femoral component of the knee joint endoprosthesis parallel to the transepicondylar line requires resecting the femur at approximately 3° of external rotation relative to the line tangential to the posterior aspect of the femoral condyles. This angle, however, may vary from 3.6° of internal rotation to 9.0° of external rotation which should be taken into consideration by the operating surgeon. 2. The values of the Posterior Condylar Angle do not correlate with gender, age, Body Mass Index and body side (with notable, near-perfect symmetry between the contralateral limbs). 3. In female patients, height and body weight may influence the Posterior Condylar Angle, but these correlations would require further studies of larger groups of patients. In male patients, we were unable to find such correlations.